The Price of Solar Is Declining to Unprecedented Lows | Hacker News Reader

The Price of Solar Is Declining to Unprecedented Lows

blogs.scientificamerican.com

276 pointstedsanders164 comments

The article emphasizes that the declining price is due mostly to peripherals & installation rather than any scientific breakthroughs of the solar panels themselves. The following quote is key:

>"This means that the decline in installed cost observed since 2012 was largely caused by a decline in the cost of the inverters that convert the DC power produced by solar panels to AC power for the grid and other “soft” costs such as customer acquisition, system design, installation, and permitting."

On another note, calculating the payback of residential solar panels is tricky because many online calculators don't consider:

  - inverters failing and needing to be replaced (~10 years?)

  - bank of backup batteries need to be replaced (~10 years?)

  - significant increased labor costs of replacing the roof or repair roof leaks (roofers must spend extra time unmounting all panels before replacing shingles or tiles.)

  - paying a service to clean the panels if the house is in a dusty climate and the homeowner doesn't want to climb on the roof and do it himself

One can lump all those negative costs into one bucket called "ongoing maintenance" to simplify things but nevertheless, it doesn't seem like many ROI calculators properly account for them.

(That said, some people pay the premium for solar panels to gain power autonomy which overrides any over-optimistic estimates of installation payback.)

Inverter failure is real, but the industry standard has risen to 12 years for string inverters, and 20-25 for micros. Even for string inverters, most of the residential/small commercial market has moved to using optimizers for voltage regulation, which means the inverter itself is a lot lighter weight/cheaper.

Backup batteries are still relatively rare, as they should be - they are fairly expensive as backup power. Most systems remain grid tied. Smaller systems don't require retail net metering for a solid payback, since almost all of the energy is used as it is produced.

Roof repair is again, real, but not as likely as you might think. Asphalt shingles under an array are protected from wind, and even more importantly, heat. They degrade at half the rate of the rest of the roof. Assuming 12-15 years for roof replacement, you will hit the module warrantied life of ~25 years before you need to replace the roof underneath the array.

Cleaning the panels really only comes into play when the pitch of the roof is relatively shallow (3 on 12 or shallower). Otherwise rain will clean them fairly well. A lot of people won't have any trouble walking such a shallow pitched roof, and will simply hose the panels off once in a while.

Also, in general, the price of modules per watt is about half of what it was 5 years ago. Peripherals are a major component of the improved economics, but module prices themselves have mattered just as much.

   > On another note, calculating the payback of 
   > residential solar panels is tricky because many
   > online calculators don't consider (stuff...)

Sometimes they do, we installed Solar in 2003, we replaced a failed inverter in 2016. At the time we installed the system we got a new roof with asphalt shingles (50 year roof) which both helped the roof load (they were lighter than the previous wood shake) and was a time period longer than the payback period for our panels.

Stick with a grid-tie system for the time being, especially if you can get the right feed-in tariffs. I don't really see the case for domestic storage systems yet.

The biggest market for domestic storage is people who would want an emergency generator anyway. You get most of the same benefit for a lower cost with a Powerwall (if the expectation is temporary outage tolerance).

IMO that's the best comparison for domestic storage though.

A Powerwall doesn't store enough energy to be worth much in a real emergency. It's going to be nice to keep your refrigerator running during a short power outage, but it won't provide days or weeks of power the way an inexpensive generator can (for example http://www.homedepot.com/p/Generac-11-000-Watt-Air-Cooled-Au... ).

Sure, you have to either trust that nat gas is available or deal with fuel, but a propane tank isn't obscenely expensive considering that it bumps your backup from hours to days/weeks.

I don't understand your argument. A Powerwall, if it can get you through the trough, means in an emergency you have the same amount of power you'd have in a non-emergency.

Clearly, the emergency he's planning for is the sun going out.

....or a winter storm that lasts a few days.

Any long storm really.

A few years ago in Vancouver a storm caused quite a number of major but localized power outages, some of which took a few days to fix. During that month or so there were a few weeks where the sun was blocked for almost the entire day - not even like overcastt.

That being said, I'd you're in a more inland area, with more sun and less clouds it might make sense.

In that case put your groceries on the back porch.

That might work for food in the freezer, as long as you don't live in an area with wildlife like bears and raccoons. It seems like a huge market for this would be off-grid people, who are going to live in the country where such animals will live. It seems like raccoons are in most American cities anyway.

You are still going to have a problem with refrigerated food - lots of vegetables spoil when frozen and frozen milk isn't much fun. Plus the house is going to be consuming lots of power from lighting and TVs as days go by.

I have family that live in very rural areas. Most of them have diesel generators or tractor PTO generators to cope with power outages that last many days. Such a situation is certainly is something that is survivable without a generator, but not very pleasant. Going through the experience once, many people realize that generators aren't that expensive and buy one to be prepared next time.

You might also wonder about running out of diesel fuel, but most farmers have 500 gallon tanks of (untaxed) diesel for equipment. Hundreds of gallons of diesel lasts a long time.

And if you have something like a dairy farm, a generator is a necessity for such a situation with a milking machine.

Storm-damage-related power outages are the killer, particularly if you rely on air conditioning. The last major storm in my area that impacted me knocked out power anywhere from a few days to several weeks, depending on the area.

It is decidedly unpleasant to be in 70+ degree heat with 80% humidity at night and hotter during the day.

The comment I replied to reads as if people without solar are going to install a Powerwall instead of a generator. Maybe I misread it.

That was what I meant. In my area at least, the longest power outage in the last 15 years was about 18 hours.

> You get most of the same benefit for a lower cost with a Powerwall (if the expectation is temporary outage tolerance).

Ehh? A Powerwall costs $3500 alone, WITHOUT the inverter or transfer switch. A Powerwall supplies 3.3 kW, which isn't enough to run a 3-ton air conditioning unit (30 amps x 240 Volts == 7.2 kW).

If you run 15kW (air conditioner plus a few other stuff), you'll need FIVE Power walls for a minimum price of $17500. (Plus the inverter, plus... etc. etc.)

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Or, you can get a 16kW generator AND switch for $3300.

http://www.electricgeneratorsdirect.com/Generac-Guardian-646...

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Powerwall is actually a lot more expensive than standard generators. Something like 5x more expensive.

Erhm, do you honestly expect to keep your A/C running during a power outage? First world problems indeed..

Insulating your property to keep heat out/in is a hell of a lot cheaper than buying enough backup power to keep your A/C running...

It depends on where you live. About 15 years ago, the geniuses of our power company decided that they could save on tree trimming near power lines. a few years later, they were bragging about the savings... and then, in the middle of winter, with about 3 feet of snow on the ground, we had an ice storm that took out power for well over half the city. My house was without power for 4 days, with highs in the 20F. There's enough population density our lives were not in danger, but the house was only habitable because we had a generator.

And guess what? 5 months later, the summer comes, the tree trimming still wasn't done, and half the city lost power again due to a summer storm. Out for 6 days in our house. Every day we reached the 90s. Good luck insulating yourself from that heat for almost a week! Having A/C was pretty nice. The power company now inspects and trims around lines every couple of years, just to avoid power outages so wide they can't bring power back at an acceptable timeframe.

That said, the situation is rather regional: I'd not care about AC or heating in a power outage if I lived in Northern California. Around here, where we can hit the 100s in the summer and go under zero in the winter, you have to care a bit. My friend in Alaska cares even more.

So first world problems? Depends on where you live.

Relying on electricity for heating should be on the list of questionable decisions, though. That changes the parameters of emergency planning significantly.

We also had temperatures in the nineties for the last five days here, yet nobody has AC in their home. It's not a big problem with insulation. Of course we also don't have non-redundant overland power lines. Power outages we super rare.

Proper passive house design in the future should ameliorate temperature issues, both in terms of heating and cooling.

From what I've heard, houses in certain humid and warm regions (like Florida) quickly succumb to mold without air conditioning. In some cases of abandoned properties, the house quickly becomes a total loss.

Ventilation != aircon. Believe it or not, people lived in Florida before a/c was a thing... And maybe use some damp proofing while you're at it.

> Erhm, do you honestly expect to keep your A/C running during a power outage? First world problems indeed..

Yeah. Lets pay $18,000 for a backup solution instead of $3000 one.

The real "first world problems" are the guys who have so much money they can afford to purchase based on ethics, as opposed to practicality.

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My power-outage plan is btw: walk to the mall / library and use their AC. If I were to get a backup unit for my house, it'd be sized for my AC unit for sure however.

"which isn't enough to run a 3-ton air conditioning unit (30 amps x 240 Volts == 7.2 kW)."

Wow, it always surprises me how much Americans waste and consider it totally normal(I bet you are American, in the rest of the world it would be difficult to emit that expression with a straight face).

Have you considered alternatives? My house in sunny Spain spends less than 1Kwatt in August pumping water in a pipeline in the soil that has a big thermal inertia, and small air conditioning units for the air.

You don't need more if you have good insulation.

"Geothermal" (as they call it here) of that sort can be had in the US, but it's very expensive to install unless you have a large yard (otherwise you have to dig even deeper) and it's difficult to impossible to recover the cost of the system at sale if you move before saving enough to justify the cost—which itself may be difficult if you consider the opportunity cost of the money, and especially if you take out a loan to do it. The buried hoses/pipes also have a limited lifespan, and will need to be replaced in a couple decades, again at great expense.

In short, we don't do stuff like that in the US (at least, not much) because it's often a good way to lose money.

Also, I don't know about Spain, but large parts of the US suffer very high humidity through much of the year. Unless you're on an exposed hilltop with a breeze, it's miserable without good air conditioning. Houses aren't build with cooling-via-open-window in mind anymore, either, having fewer and smaller windows than older houses and being built with no thought to positioning the windows and the house itself such that prevailing winds can blow through it. Many interior materials aren't intended to tolerate even moderate temperature and/or humidity swings anymore, and will deteriorate much more quickly under those conditions. So there aren't many days in a year when it's possible to get by with no heating or cooling and just open your windows, either.

> Have you considered alternatives? My house in sunny Spain spends less than 1Kwatt in August pumping water in a pipeline in the soil that has a big thermal inertia, and small air conditioning units for the air.

Lol, Geothermal costs more than the electricity prices. Geothermal costs $25,000ish. It'd be cheaper to install the Powerwall!

In my state, a kWhr costs $0.08. Large air conditioning units are more efficient. I have a programmable thermostat that keeps the air conditioner off the vast majority of the time.

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The name of the game is to buy big, efficient units. They draw a lot of power while they're on but then they shutoff once your house reaches 76 degrees (or ~24.5 Celsius).

Again, you buy big to be more efficient. We've run the math already. A big efficient whole-house 3-ton AC unit for $1500 is much much cheaper than a Geothermal unit of $25,000.

Then get a programmable thermostat to keep it on only when you need it.

Spain is pretty darn temperate. Average daily highs don't even rise above the 90s in the hottest months. There are a lot of areas in the US that are far hotter, and if you're thinking about taking advantage of solar energy, chances are you're in one of them.

You're assuming that the capacity of the Powerwall is all the power available. With a solar-tied backup system, there is power coming in from the modules as well which is additive to the discharge rate of the Powerwall if wired correctly.

So even your massive A/C should be useable for a while during daylight hours if your solar system is large enough. Most people here in humid hurricane country opt to have a 15 amp 120v window unit available instead, and limit themselves to a single comfortable room.

> You're assuming that the capacity of the Powerwall is all the power available. With a solar-tied backup system, there is power coming in from the modules as well which is additive to the discharge rate of the Powerwall if wired correctly.

That still begs the question: why use Solar + Powerwall when Solar + Gas Generator has higher capacity and is cheaper?

> 15 amp 120v window unit

1800 W, which is more than half the capacity of your Powerwall. Not enough electricity left over to run a single-room AC and a dishwasher at night.

Got an electric oven or stovetop? 4000W or so? Yeah, Powerwall just ain't gonna cut it. 3.3kW capacity is just way too small for the typical house.

The answer to backup is frankly Solar + Generator. Battery backup just doesn't have the specs or the price to be practical yet.

Or, solar+battery+generator for uninterruped power while still keeping costs low compared to a large battery?

What does the battery accomplish? I mean, maybe an UPS for your computer if you're running something mission critical? Something that can last for 20 minutes while the generator boots up?

But I don't think most people are running mission-critical programs at home.

In my home, a single Powerwall battery could cover 90+ percent (or perhaps 95+ percent?) of nights even in an off-grid arrangement. Covering the rare extremes with a $150 generator would be more cost-efficient than using a larger battery, and likewise, covering the usual case with a battery would be more cost-efficient than running all nights inefficiently using our $5/USgal gasoline.

Why go off-grid when Net-Metering exists?

Y'all have thoroughly convinced me to disregard Powerwalls :)

> why use Solar + Powerwall when Solar + Gas Generator has higher capacity and is cheaper?

Because Elon Musk! Senpai notice me!

I suppose you mean the 'economic case'. Some people is doing it for other reasons, as is frequently the case for early adopters of any technology.

I suspect that one reason for a domestic storage system would be having solar in one of the states where the power companies have imposed punitively high charges for tying to the grid.

You have a good point re roof penetrations. There are too many cowboy solar installers casually drilling holes thinking a blob of silicon is enough to seal out the rain. Also, when you eventually want to replace the roof handling and reinstalling the panel probably doubles the labour costs.

This was a reason I put solar in after installing a standing seam metal roof. The roof will last 50+ years, and the solar just clamps onto the seams. Only penetration is for the cables to the inverter.

My thought is that you would install the solar panels when you're replacing the roof. Put 30 year panels on a 30 year roof. 30 years later you get to do it all over again, but at least you're not removing and reinstalling the panels when you replace the roof.

Even without solar, few last 30 years without major repairs where I am (pacific northwest). There are lots of things to consider. Some/most solar installs don't take debris into account, creating dams that can send water places it shouldn't be, like up and under shingles. Not an issue in the desert but in rain forest it is a big deal. And the number of penetrations ... I've seen people put dozens of screws through what used to be a good roof. They cannot all be perfect.

Around here (midwest) hail or wind usually knocks out composite roofing in 10-15 years—much less if you're unlucky. There's little point in springing for the "50 year" composites and similar.

I guess the solar panels would protect the roof a bit, but I'd expect a bad hail storm to be bad news for those, too.

Not only that, but it's not uncommon for panels to crack. Kids throwing stones or balls, weather-related, etc. Replacing the glass is often difficult or expensive. Alternatively, you can fix it but that will often reduce the clarity and thus the generated electricity.

Panels are sturdy enough to withstand 4 inch hail and hurricane winds if properly mounted to a roof or concrete ground support.

>The article emphasizes that the declining price is due mostly to peripherals & installation rather than any efficiency breakthroughs of the solar panels themselves.

Over the last few years racks, mounts, wiring, inverters and labor have made up ~60% of the cost.

Plus, Obama started slapping ~30% tariffs on the cheapest imported solar panels.

Not sure why you're being downvoted, I assume the ~20℅ anti-subsidy rates plus the individual anti-dumping rate referenced in the below article are what you're referring to?

http://www.bloomberg.com/news/articles/2015-07-09/u-s-impose...

Yep that's the one.

I read the state department report too. The 'disguised subsidies' they called China out on included 'advertising' the solar companies' existence on local government websites.

Clearly they didn't expect anybody to actually read that.

In the US, I'd image tariffs on panels having a much lower influence then elsewhere in the world. Even if panels were completely free in the US, a US-based residential solar system is going to be more expensive to install than even European ones (including European panel costs).

If you liked the sound of this article, there is even better news:

* solar panel prices have dropped a whole lot in 2016 already. Chinese PV panels now cost about 43 cents a watt. Production costs are around 37 cents a watt. (that's for Jinko Solar)

* utility solar is seeing improvements in construction (more robots), cable management, medium voltage something or other at the power plant, etc.

* China PV makers are moving to PERC and maybe more to Mono. This means a little more efficiency. First solar supposedly has their CdTe response.

* be careful before you go and invest in solar. (FSLR, SPWR, JKS, CSIQ, JASO) As I learned, there is a coming shakeout in 2017. The long term extension of the ITC in the US ironically caused a slowdown in deployment b/c utilities are no longer under the gun to receive the ITC. China also lowered their subsidies for the second half of 2016. Meanwhile PV makers increased production.

> * solar panel prices have dropped a whole lot in 2016 already. Chinese PV panels now cost about 43 cents a watt. Production costs are around 37 cents a watt. (that's for Jinko Solar)

However, a 140-watt panel would cost me 362 dollars back home, which is 250 cents per watt: http://www.sunwind.no/product/show/?id=1297

Where exactly are these oh-so-cheap panels supposedly sold?

The usual place:

http://www.aliexpress.com/item/solar-panel-12v-50w-poly-2-pc...

That seems great at 50 cents per watt, but the shipping is another 91 cents per watt.

Good place to start looking though.

I have thought (never tried, though) that large shipping costs in Aliexpress are indicator that supplier wants to discuss the true shipping cost with buyer.

Note also that at least in EU you need to add customs and VAT. And you can't expect always getting top quality if you order the cheapest you can find in Aliexpress.

Again, in EU, it might be easier to buy e.g. this:

http://www.ev-power.eu/Solar-Panels/Solar-panel-GWL-Sunny-Po...

(plus VAT, but already in EU)

If you want good prices you need to buy a whole pallet or more of panels: http://sunelec.com/solar-panels

I tried the first hit on UK ebay and got £105 with free delivery ($137, almost exactly one dollar per watt) http://www.ebay.co.uk/itm/NEW-140W-12v-Energy-Solar-Panel-Po...

There must be cheaper panels available in the US.

Renogy has 100W panels for $145 stateside https://www.renogy.com/renogy-100-watt-12-volt-polycrystalli...

140 W is probably not the cheapest-per-watt panel format.

Why don't you visit Germany with a van?

Chinese PV are made in a country where electrcity is mainly produced with coal. All construction carbon emission taken into acount, they need around 30 years of use to get carbon neutral, generally more than their expected life time. This is not sustainable at all yet.

What study says that? These fliers both say less than 5 years for energy payback (as little as 6 months...):

http://www.nrel.gov/docs/fy04osti/35489.pdf

http://www.clca.columbia.edu/236_PE_Magazine_Fthenakis_2_10_...

It doesn't make any sense that China would be subsidizing their panel manufacturers to the extent you are implying.

Energy payback is not the same as carbon neutrality. The former only accounts for the economic value within a regional market and ignores externalities.

Just compare the price of a solar panel with the price of coal you'd have to pay for in China. That's the uppermost possible limit of what you could expect for CO₂ emissions if you didn't have to pay for anything else. Just conveniently assume all your workers and other raw materials are free. ;) You can probably buy two tonnes of coal in China for the price of a ~250W solar panel. That gives you about 4000 kWh of electricity. At a 15% capacity factor in China, the same panel can generate at least 6500 kWh in 25 years, even including quite substantial degradation. So if used to offset electricity generation within China, it's neutral after 15 years.

In reality, it's most likely much sooner because you don't need 4000 kWh of coal electricity to manufacture a 250W panel; you have to pay your workers and raw material suppliers instead.

Sure but if the energy return is 15x the energy investment, carbon neutrality is pretty likely.

All energy is not created equal. In order to make this calculation in a useful way, one would need to know the amount of carbon emissions per kWh for both the panel production site and ones local grid. And it's actually even harder than that, as one also needs to know if one is lowering base-load generation needs or surge-capacity. Base- and surge-generation are frequently not the same as carbon emissions go.

Consider for instance that you live near the Hoover dam (desert, lots of sun, prime area for solar); your panels might never be carbon-neutral.

Sure, it's complex. Take your example. The Hoover dam sells power into California. So installing solar panels in Boulder City is not that different than installing them in Los Angeles (there would be some extra grid losses in LA). If the Hoover Dam had the capacity to supply the entire southwest it would matter, but it doesn't have that capacity.

There's also the question of whether buying Chinese solar panels makes China more or less likely to convert to solar itself.

Even in a 100%-coal grid, I don't think it's likely that >1000 kg CO₂/kWp is necessary. German manufacturers can achieve 400 kg CO₂/kWp in the still-rather-mediocre German grid.

They are the same.

If energy is the only input to making a solar cell (the worst case) and the cell costs x Wh then the market price can't go below x * ($/Wh), so it pays back when you produced x Wh (thus not buying x Wh from the coal burning power plant) and any energy you produce is both profit for you, and also less total demand for coal energy.

Don't have the details of the study, it was from an informal evaluation from Jean-Marc Jancovici, a well known (in France) climate/energy specialist. A similar argument is made here:

http://spectrum.ieee.org/green-tech/solar/solar-energy-isnt-...

Related quote: "If the photovoltaic panels made in China were installed in China, the high carbon intensity of the energy used and that of the energy saved would cancel each other out, and the time needed to counterbalance greenhouse-gas emissions during manufacture would be the same as the energy-payback time. But that’s not what’s been happening lately. The manufacturing is mostly located in China, and the panels are often installed in Europe or the United States. At double the carbon intensity, it takes twice as long to compensate for the greenhouse-gas emissions as it does to pay back the energy investments."

It's not that similar an argument, it suggests a carbon payback time of 3-10 years, not 30 or never (10 years is unfortunate but workable (especially if you expect it to improve, which is basically guaranteed), 3 years is fine, never would be unacceptable).

True, that depends on the country where the PV panel is installed. The original argument was probably made for France where electricity is very low on carbon.

You're not taking into account future emissions. If everybody stopped buying PV cells from China, that would severely retard the development and rollout of PV, and so cause more emissions.

Not sure. PV generated electricity is around one percent worldwide. CH4 and coal thermal stations have the lowest investment price per kW, so booming economies won't invest massively in PV until CH4 and coal get very expensive. Add to that that PV is very dependent on geography and does not work at night, to make it more than a day peak adjustment you have to also invest in batteries that cost even more carbon-wise.

China is not the only country which produces PV panels. PV panels are also not the only choice in alternative energy. If one is interested in reducing carbon emissions, it's so much more complicated than "just buy solar".

That country needs to move away from coal as fast as possible for public health reasons and know it. So they'll build massive production capacity anyway irrespective of carbon neutrality etc. (and we in the rest of the world will benefit)

China already has the biggest hydro electric project and I to see massive installations in China for Solar, Wind and Nuclear to combat their air pollution and health problems

'That country'? So does the rest of the world...

You can easily determine that this isn't true on first approximation by multiplying the rated output of the panel by thirty years, and dividing that by the price of electricity. It's well more than the panels are selling for. It wouldn't make any sense for them to sell for so low, so they aren't. It'd be like claiming that the raw materials that go into a $20K car cost $100K. Obviously, they don't.

I'm very interested in reading more about your last point. Where did you hear about this shakeout? Will it affect companies had invest in solar projects like Wunder?

Re: investing in solar producers and a coming shakeout

This makes me think of some interesting structural economic issues I hadn't considered before.

Compared to the global distribution networks of hydrocarbons, distributing PV panels is uncomplicated and a lot less bulky. On the other hand consolidation in the industry and eventual economies in scale of production could point to less diversification at the lowest levels of supply compared to a system where individual wildcatters, new tech like fracking, and even cartel members (and outlaws/terrorists) undermining their quotas have a not insignificant effect on the cycles of energy pricing and supply.

Even technology with a well-defined trend toward decreasing prices like RAM or hard drives have this complication if you need to make your purchases right after floods in Thailand, or at the wrong time when a standards for RAM are coming into effect or stopping production.

With a small number of huge suppliers, and decades long replacement cycles leading to boom and bust cycles for the industry, it could be as difficult for users to plan energy supply needs as it has been when it comes from mismanaged areas of the world.

Interesting:

> The continued decline in total installed cost is noteworthy considering the fact that the price of the solar panels (or modules) themselves has remained relatively flat since 2012. This means that the decline in installed cost observed since 2012 was largely caused by a decline in the cost of the inverters that convert the DC power produced by solar panels to AC power for the grid and other “soft” costs such as customer acquisition, system design, installation, and permitting.

That's right. A friend, here in India is making a decent income by selling accessories - connectors, wire(sun/heat resistant), batteries etc. Importing Solar panels in India or manufacturing is still with the bigger players. But accessories is easy to get in. Also companies providing installation services aren't all that profitable, because cost of labour is cheap here and the margins are low. In installation you're basically only playing in the 15-20%% of a crowded market. But if you consider the over manufacturing capacity of China, accessories import/export/manufacturing remains a lucrative segment of the business.

I'd believe it. I priced out a solar install a few years ago and they were straight up ripping you off on the inverter and the install costs. There was a lot of room for movement in that area.

Consolidation.

This is great news, there should be a large push now to base large parts of the grid on solar (and of course wind). Not accounted in the costs of conventional power generation is all the environmental impact - factoring that it, solar probably is already cheaper.

Another seldom mentioned fact is, that solar plants don't have a minimum size. So for large regions in Africa, where there is no grid yet, it is much easier to set up isolated small solar plants in villages than to construct a whole grid.

There is environmental impact in solar too - the manufacturing processes for photovoltaic cells aren't exactly clean, the raw materials still need to be sourced, installations spread out over mile after mile need vehicles to maintain etc etc.

But the real elephant in the corner of the room is that there is no really good method yet for buffering power generated by solar by day, for consumption overnight, when it is needed for lighting, heating, cooking, etc. A conventional station doesn't care what time of day it is. THAT is the barrier to widespread adoption, and it's one that solar proponents always seem to overlook...

I'll keep posting this until I see someone else on HN posting itbtoo: Flow batteries are here now, cheap, and work well. They don't have the power density of the Tesla batteries, but for residential and light industrial use they work well.

Flow batteries have two basic problems.

One is that they deal badly with usage intermittency - one must be always charging or discharging them, you can't just store them.

The second is just, where do I buy one? Nobody seems to make them, no idea why. Maybe this one solves itself when solar gets widespread, or maybe there's some government hand in that and it won't be available when we need it.

One is that they deal badly with usage intermittency - one must be always charging or discharging them, you can't just store them.

That isn't really a problem in home use. You just run your power though them, and dump any excess to the grid.

For industrial use http://redflow.com/, and just starting to hit the residential market now

(Disclaimer: I work in the same building as a Redflow office)

I'm waiting for vanadium redox batteries to go mainstream myself https://en.wikipedia.org/wiki/Vanadium_redox_battery

Can you recommend an online supplier or a particular model?

Note that the article is about big solar, not home solar. Big sites with lots of sun and no clouds are very cost-effective. Mojave is filling up with solar panels. Random house roofs, not so much.

The head of Applied Materials solar operations had a useful way of looking at costs. He'd draw a latitude line on a map, saying that below this line (Northern hemisphere) solar could beat out other sources of power without subsidies. About ten years ago, that line ran through Spain and Southern California. As the costs decline, it moves north. This is more useful than looking at costs over all locations. Solar is a location-specific thing. SF's BART system once looked into solar panels at stations, and decided that only one station in the whole system (Contra Costa) got enough sun to justify it.

Tesla is making noises about "solar shingles" for residential installations. The idea is to replace the roof, rather than sit on top of it. Others make those now; CertainTeed Products, for one. Dow Chemical just exited that business. Solar shingles work, but high installation cost and lower efficiency make it unproductive.

>Note that the article is about big solar, not home solar.

The article mentions "residential systems" twice as points of comparison. It also references the 5% reduced costs in home installs in the subtitle of the article.

I don't really see what the relevance of a foggy coastal city is to the general solar market.

Most of BART's above-ground stations are not located in a foggy city.

Levelised cost of energy (LCOE) is a good metric for comparing energy sources on cost [1].

According to the table on page 6 of this EIA report for weighted average LCOEs in America before tax credits for 2022 [2], photovoltaics are projected to be around $74 per MWh. That compares favourably with $100 for nuclear, but unfavourably with $56 for natural gas, $59 for wind or $64 for hydroelectric. (Solar gets a weighted average federal subsidy of $16/MWh subsidy; wind $8.)

[1] https://en.m.wikipedia.org/wiki/Cost_of_electricity_by_sourc...

[2] https://www.eia.gov/forecasts/aeo/pdf/electricity_generation...

So basically rooftop residential solar isn't going to be economically viable any time soon - it's more or less bottomed out and is still much more expensive than conventional generation and utility-scale solar, and the latter has further potential for cost reductions.

Thing to consider is when you compare costs you need to compare against the alternative sources at the particular point and time where solar power is injected.

A lot of times you see solar prices compared with base load power prices, but solar competes actually with natural gas[1] fired peaking plants which sell power at higher prices than a coal fired plant.

Similarly residential users are charged a substantially higher price for electricity than the base load price. Partly because a substantial amount of power comes from peaking plants and because the utilities have a grid to maintain[2].

[1] If you wonder why the Koch brothers hate solar remember they are in both the oil industry and the gas industry. Little of the former is used for power generation where peaking plants use lots of natural gas.

[2] Utilities hate roof top solar because it messes with their economics because their bond payments and maintenance costs are fixed.

Why do you place solar with peak-load technologies like gas? The point of peak load plants, and why they charge a premium, is that they can ramp up output when there is sudden demand. Solar does not have that ability, just like coal and wind.

Guessing because the peak-load for electricity tends to coincide with very hot days. So lots of demand for air conditioning but the solar panels are also generating maximum capacity.

Not entirely true. PV panels perform better on cold sunny days than on hot sunny days. Semiconductors and heat are still no match made in heaven...

The peak demand for electricity is around the afternoon of the day, and it gets higher the hotter the day is.

Which is exactly where solar is available – it can’t deal with 100% of the peak load, but it can take about three quarters of the market for peak load techniques.

That's true for now, but it'll be interesting to see what happens as battery prices come down. There's also an interesting synergy between used car batteries and home storage: http://thinkprogress.org/climate/2016/05/09/3775606/used-sec... or http://fortune.com/2016/06/22/bmw-energy-storage/.

It's viable with the right subsidy regime, as are all the power sources once they're made to deal with their externalities and variances. http://www.bbc.co.uk/news/business-27142377

It'll take a few years, even the suppliers are not focused on residential rooftops (atleast in India). Although several state govt's regulations that industries of a certain size need to use solar energy is encouraging growth in that segment. Residential rooftop installations will take at least 2-3 years and govt incentives, to pick up. But the market is moving for sure!

How did you come to that conclusion? Actually just curious.

It seems like there could be a really big difference between the cost of conventional power between Australia and the US if what you're saying is true.

US residential rates average $0.13.

https://www.eia.gov/electricity/monthly/epm_table_grapher.cf...

Looks like they are ~$0.23 (that's US dollars) in Australia.

I guess the sun is better in Australia too.

Rooftop is viable if one accounts for a possibility of future price hikes or disasters that leaves the house without grid for substantial amount of time. Essentially one treats the extra cost as an insurance premium.

You can justify the cost of anything if you compare it to a made-up scenario where having the thing is far better than not having it. That's just rationalizing; it's not a valid analysis.

If your looking to buy a generator and tie it into the house grid for X$ and desire not to because your installing solar then that's real savings. For survivalists who want 1+ years of gas X gets rather large.

Even if you just have regular power outages, or are a data center, hospital, etc that is required to gave full power off grid for days solar becomes far more attractive. Solar is also rather atractive to the military as logistics get complex and expencive.

The examples in your second paragraph are not made-up scenarios; they're real needs caused by faulty power grids or large-scale disaster-management requirements. For those it makes sense to compare the costs of different off-grid power sources.

Your first paragraph, and the post I replied to, aren't like that. Is someone looking to buy a generator because they just want one, or "something may happen", or do they actually suffer from power outages? As for survivalists, most of what they do is based entirely on their beliefs and world-view rather than verifiable facts, so they're a perfect example of what I'm talking about. (I'm not saying they shouldn't do what they're doing; so long as they're not hurting anyone I think they should be free to believe what they want and act accordingly. I'd just like them to be honest, with themselves and others, about why they're preparing to be self-sufficient.)

BTW, I'm pretty familiar with the faulty power grid scenario. Even in my very densely populated neighborhood all of the houses on my street and one or two others used to loose power during every big storm, because for years the electric company just patched the lines that kept getting knocked down by tree movement instead of fixing the problem. Some of my neighbors had generators, and it became common to have a network of extension cords criss-crossing the street for a few days after a storm. Solar would have been pretty useless, since it's usually not sunny during big storms.

I recently came back from a year in Puerto Rico with a similar situation. The utility company didn't do proper maintenance and the electrical system uptime was about 93% every month.

With the grid mostly being up, but not being reliable, the most logical solution was a gas generator to provide power during the outages. All the gas stations had backup generators, so the general operating procedure was to just keep a 5 gallon gas can handy. If the power was out for more than 12 hours, we just went and got more gas. The frequent outages meant that the gas was used often enough that it wouldn't spoil.

I'm moving up to upstate New York soon and my experience in PR has made me wary of multi-day outages during blizzards, so I'll likely replicate the setup.

If I ever live in a place with natural gas lines but worry about power outages, I'll likely get a natural gas generator. Even during power outages, natural gas lines stay pressurized because the gas distribution system burns the gas itself to power the equipment they use to boost the pressure for the system.

While I don't think it's a reasonable need, people really do build under ground shelters etc. Also, solar works on cloudy days if you can see there is light that can be turned into electricity. Worst case where there is enough cluds it's basically dark you get ~10%. What stops working is concentrating solar aka those big plants with lots of mirrors.

PS: Even just moonlight can provide very tiny ~1/20,000th, but measurable amounts of power.

For my particular experience, that still wouldn't have helped. First, the storms that knocked out power mostly occurred at night and had 100% cloud cover, so we're talking about total darkness. There was also really heavy rain or snow, which I'm sure makes the panels less effective even when there's light hitting them.

10% or less power wouldn't be enough, I think. The goal would be to keep the refrigerator and some lights running, and during the winter my heating system needed power for the electric ignition on the gas-burning boiler. (Why those things don't have a backup manual spark ignitor, like a gas barbecue, is beyond me.) During the storm this would all be without power, though I guess solar would help during the day once the storm passed, so long as the panels weren't covered with snow.

10% is generally the extreme low end and not something your going to see repeated for several days.

If you want days of off grid use your going to have battery's anyway. If your willing to cut back on energy that much then you might not need to even clear the snow from your panels. But, there is a wide range of easy solutions to that from manual clearing with a long pole, heating elements, or even just a steep mounting angle.

One major upside is the system should be automatic so you can leave your house unattended through a major storm. However, from a cost perspective solar hot water systems are generally worth it long before solar panels in the north.

Unless you're running that datacenter or hospital only part of the day, you're still going to have a fuel-based generator in your scenarios.

Battery's work ok for regular short term power outages, but going 2-7 days after a storm is not that uncommon every few years in many areas. At which point solar for charging in the day + battery backup is a good solution vs grid + generating capacity.

Basically, installation costs with solar are high, but they don't increase much as you scale the system. Battery's let you scale further, reducing price per watt. You also need an inverted for battery's which you can reuse with solar.

Can you point us to a hospital or commercial datacenter that has solar and batteries and no fuel-based generator?

You would need solar generating capacity well in excess of demand (to serve the daytime demand AND fully charge the batteries on an overcast day to address a multi-day outage). That seems far less practical than a mechanical generator as backup.

Storing a year of gas is just stupidity, even for a crazy survivalist.

Less insane use cases for generators are a week or two, mostly to keep heat, well pumps, and refrigeration up. A generator for that purpose is about $3k installed, and goes up with output.

The off grid use case is a fringe thing, because most if not all states require grid connections for residential construction.

I live in Portland. Lots of small, one-story houses being torn down and replaced with something that has 2 more floors.

What surprises me is that roofing on these new homes isn't required to have a south-facing exposure. Seems like that would make it a lot easier for homes to add solar.

Maybe they don't want solar or don't want their roof facing that direction. Let people do what they want with their belongings. If south facing roofs have higher demand it will be reflected in the value of the home.

> Maybe they don't want solar

They will when the cost of traditional electricity is priced to better reflect it's environmental impact.

In fact, I personally think nobody should be permitted to not have solar in a new building in 2016. You can't remove the seatbelts from your car in 2016. You can't build a new building with asbestos in 2016 and you can't turn your semi-auto rifle into a fully-auto (in most states). Just because you own it, doesn't mean you can do anything you want, that argument makes no sense.

If all roofs had south facing PV panels, there would be huge peaks at noon. This is already a problem in some German towns, where the installation of new south facing panels is no longer allowed.

Lobby your local representatives to update their code to require it. The increase in monthly mortgage payments to roll the system in at construction time is less than a utility bill would be (typically).

Isn't it too cloudy for solar there?

Not a word about subsidies on solar power. Has anyone got any data on raw cost of solar power, without taxpayer's subsidization?

The article was talking about the raw, unsubsidized costs of solar. It is now on a level, where it can compete on a price basis with conventional energy production. And that does not count in the hidden costs of coal/gas/nuclear as their environmental impact rarely gets accounted for.

Here in Germany, rooftop solar electricity costs about half of what the utility companies charge off the grid.

... because utility companies have to collect a price that covers the subsidies going to solar and wind producers, required by law.

Even if you deduct that amount from the utility prices, the grid electricity stays higher. Of course that has also good reasons - the grid has to paid for, and the grid is guaranteed to be available 24/7. Still this shows that solar is price competitive.

Depends on market, and depends on time of year, of course.

At least over here (Finland) the problem with wind and solar energy is that when you actually need electricity (say, a cold winter morning), both solar and wind power output are locally zero.

To alleviate this, you need a grid, and energy storage, and spare capacity.

Right, but Finland shouldn't be the benchmark for solar power viability. The total population of places with a climate similar to Finland's is quite small compared to areas where solar is viable.

On the other hand, places where local solar is particularly viable (like Sahara) shouldn't be a benchmark for off-the-grid solar viability either, because not that many people live there. In practise, you really do need to have grid and storage to use solar.

(Local off-the grid solar is somewhat usable even here, but it does need battery storage. It is popular in holiday homes that are not located close to power lines. E.g. I have a cabin which is a kilometre away from nearest electric lines; building a power line to the grid would cost in the order of 50 k€ while an off-the-grid solar-powered system runs electronics and a fridge with an investment in 5k€ range.)

Exactly. Maybe Germany would be a reasonable benchmark, if one factors out the subsidies (which used to be very attractive, I'm not sure about the current status). There are lots of rooftop solar installations in my area (southwest).

I agree, subsidies are very important to discuss! For comparison, some IMF researchers claim that fossil fuels are subsidized by $4.8 trillion per annum (that's more than 5% of global GDP):

http://www.imf.org/external/pubs/cat/longres.aspx?sk=42940.0

The subsidies tend to come back as payments for the electricity generated so the installed costs will be the same as in the article. I installed a 16 panel, 4 kW system on my roof in 2012 for around £10,000 - and receive a subsidy of around £0.45 per kWh generated.

An interesting finding this. The national power provider in South Africa (Eskom) has decided to go against the tide and focus on coal powered power stations. They have concluded that they won't be buying power from independent power providers which for the most part generate renewable energy. Maybe such researches and a more firm stance from institutions such as the IMF will help us in this regard.

Unfortunately, PV market price drops do not reach the EU market, due to the anti-dumping and anti-subsidy duties on crystalline silicon modules and cells originating from China in place since 2013. These protective measures have caused the solar module prices to even rise during the last two years (and certainly hampered solar deployment in Europe).

Article only shows "total installed cost". For an individual, that's great. But i would have liked to see the actual numbers that go into that itemized. If the "costs went down" because tax rebates went up, then we're no closer to solving any real problems.

Makes me wonder about the deflationary effects. Eg, would it be rational to think "I could buy a solar system now, but if I wait a year it will be cheaper by a large enough margin it's better to pay more in electricity until then"?

Huge fan of solar here. But I don't think the argumentation in this article is very convincing. 5-15% in a year? That's maybe a huge price drop for the industry, but for the average user it's barely worth mentioning. Maybe I'm just impatient. I want to see that stuff everywhere. Solar roads, solar train walls, solar sun umbrellas, maybe solar sun cream to charge your phone with your fingers, who knows.

And honestly I can't even say why. Water, biogas, wind. We already have quite a range of responsible energy sources. But none of them are as exciting as solar power to me. Nearly like a Mars colony. Not much logical reasoning behind it, but still quite exciting.

> but for the average user it's barely worth mentioning.

a reduction of 5-15% in a year is huge. are you familiar with how compounding works? that means the price will fall by almost half in about 5 years, and will be a tiny fraction of what it costs today, in a decade. what's expensive today will be economically viable or even cheap in just 2 or 3 years.

look at the graph! it's right there with easy to read colors and shapes.

>> Water, ...

Look into the new science on that one. It can make carbon sense when you flood a desert to feed a hydro dam, but if you flood a forest then the carbon math isn't so great. Microhydro seems an answer, but there too you have to calculate how much forest is being deprived of water, and what that means for carbon uptake. It's probably still better than coal, but it isn't perfect.

Generally with small-scale microhydro (low single digit acres) you get good biomass production because you've created more edge. Edges between biomes (estuaries, forest-field transitions, etc) are the most productive and diverse places in nature because you get overlapping species and the associated beneficial interactions.

Many small dams produce a lot of forest-water edge cumulatively, unlike a few huge dams.

Interestingly if the price is falling that's motivation to not buy. Why install solar today when it will be cheaper tomorrow?

While I do agree that it is a bad time to invest in electricity generation business in general, an electricity consumer would invest in solar today because he has some saved money today, and it's the best ROI around. (Or wouldn't, if it isn't.) The price it may have tomorrow does not change the overall picture.

Couldn't the consumer deduce that the better ROI is to keep the money as cash (or some other liquid investment) for 2-3 years and then spend it on solar in 2 years time? My expectation of future prices definitely affects how I spend my money today.

Yes, there are possibilities for speculating, but you are betting prices will fall faster than inflation + the ROI of your investment.

Plenty of people don't want that kind of risk.

Maybe it's that a dollar today is still worth more than a dollar tomorrow.

With that logic no solar power plants that exist now would ever have been built.

Incentives phase out over the next few years.

So why aren't utility companies installing solar panels on my roof just yet? Why is the upfront financing of solar panels still a problem?

Because it's more cost-efficient to build and maintain a giant solar farm https://en.m.wikipedia.org/wiki/List_of_photovoltaic_power_s...

Solar panels are loss-making for utility companies. If you have them on your roof you're not only not consuming their electricity and not paying their margins, they might have to pay you.

Worse this usually happens during the times when they make the most profit (daytime/summertime).

They have every incentive to try and kill solar - which is, in fact, what they've been trying to do (google for 'ALEC solar' to see how).

>They have every incentive to try and kill solar

Maybe where you live. But most places in the world, power generating utilities are publicly owned and price regulated and the incentive is to reduce costs. No corporate conspiracy here, and still no solar panels.

Here in Australia power utilities are private but regulated. They still want to kill solar because their networks aren't designed to cope with it - the cost structure is all wrong.

They already are trying to stop/slow personal solar. Look up "net metering laws". No conspiracy at all, its in the open. They have no incentive to reduce cost, they have incentive to stay alive.

Couldnt remember the good information I had on the subject at this but a quick google search gave me an article thay covers some of the basics.

http://www.vox.com/2014/9/29/6849723/solar-power-net-meterin...

Apparently you live in Canada? So, duh.

I've visited a number of countries twice in the space a few years (e.g. Myanmar) that have very obviously have had a huge number of solar panels put up in that period. First none at all - then everywhere.

It's most noticeable in sunny areas that have no grid at all or one that is very poorly functioning.

Ok, so why aren't other companies financing them upfront?

They do. Elon Musk's SolarCity for instance.

Many places divested transmission from generation. The transmission people don't care, and the generators want to maximize return on their assets.

because you mainly need power when the sun isn't shining. Once you add in costs of electricity storage it's not economical.

Not really, you mainly need it during the day for commercial demand. At the moment we're still in the phase of "negative demand" in almost all countries, where there's no question of storage and it just manifests as the ability to turn fossil power stations off. The UK has at the moment turned off most of its coal generation capacity for the summer.

(Is there a US equivalent of http://www.gridwatch.templar.co.uk/ ?)

Here is a live graph of power production/consumption in germany. You should take the prediction for the rest of the day with a grain of salt though.

https://www.agora-energiewende.de/en/topics/-agothem-/Produk...

What you'll notice is that Lignite (=Brown Coal)+Nuclear+Biomass+Water (i.e. the base generation) are sitting at the lowest point of consumption for the day.

Solar will only be able to increase (without storage) until there is no black coal used.

Correct, but Wind is already taking over large parts of the lignite part.

And the pumped water is storage for solar, btw.

For us as a society, it doesn’t matter if we end up with 100% solar, but only that we end up with 100% combined of Biomass, Pumped Hydro, Wind, Solar, Water.

My biggest electricity draw by far is air conditioning when the sun is shining.

"If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it." --Reagan

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