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Comment by toomuchtodo | Hacker News Reader

Relevant quote: "Every time you double producing capacity, you reduce the cost of PV solar by 28%."

Current worldwide PV manufacturing capacity is roughly 165 GW [1] [2], with a utility scale price close to $0.01/kWh [3]. Manufacturing capacity is doubling every ~4 years. Global PV capacity in service is ~600 GW.

IEA Average global annual capacity additions in main and accelerated cases, 2023-2025: https://www.iea.org/data-and-statistics/charts/average-globa... [4]

[1] https://www.statista.com/statistics/668764/annual-solar-modu...

[2] https://www.iea.org/data-and-statistics/charts/solar-pv-modu...

[3] https://pv-magazine-usa.com/2021/04/12/saudi-arabias-second-...

[4] https://www.iea.org/reports/renewables-2020/solar-pv

EDIT: Thanks to /u/gok for the correction on energy units.

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I think researchers underestimated how much solar simply “makes sense” to the average person. Once the price is reasonable enough, people are very easily able to latch onto the idea of using what they already know and feel - the sun’s heat.

Whenever I mention the solar panels in my parents house, the first question is always about the price. When I tell them they will break even in a few years, their next question is always about where to get it.

There is never any skepticism about the technology, the safety, the long term impact (as you would have if someone was setting up a nuclear or gas power plant). They simply “get it”

> I tell them they will break even in a few years

Then why don't more companies offer to become your electricity provider and install the solar panels for free?

They could say "We promise that your energy bills will be cheaper this year than last year (as long as you don't use more energy), and within a few years you'll own the panels and can switch to a different electricity provider."

Because if you want to do it at scale it’s cheaper to install some GW on a field somewhere than bothering with roofs of privately owned residential buildings.

I totally agree, but my partner says - fields for forests, not for stock or solar. We can totally pull it off using roofs, but I agree it costs more and is not possible for some.

Lithuania has this solar share that you can buy - the only option for most people as they live in apartments, but you do get dicked by monthly maintenance fee.

Yes, it's cheaper for utility scale solar because the environmental cost of dedicating land to an industrial purpose is ignored.

In the case of solar it is still preferable to do fields of solar to replace carbon-emitting power generation though.

But I do think governments should subsidize rooftop solar to within shouting distance of "utility" solar.

Heck I think they should be subsidizing solar and storage regardless of location. Once tech curves make existing utility installations obsolete in a few decades, then maybe move them back to rooftop.

Or because that environmental cost isn't actually large (if it were large, what would that do to the cost of agriculture and food?)

Pretty sure there are companies that do this. My parents received an offer like this, structured like a lease with a small buyout at the end.

Solarcity does this

They should start with large parking lots in the southwest. The installation will be predictable and it would provide valuable shade for parked cars.

At first, I don't think the business model was there yet. I haven't read a recent report so I know it is out of date, but on the order of half the costs were installation. If the company maintaining a contract on your roof goes out of business? Who owns the panels? Who funds a company where if it goes bankrupt they have contacts that give away their remaining assets?

Now that property owners understand it better I think there's less hesitation and I have seen it more. We're even getting some on our building before long.

But there's also the issue of trust, which is coupled with ownership. If your friend convinces you to borrow $5k as a homeowner line of credit, install panels (and own them) and that you will make it back in lower bills in a few years that's a lot easier to swallow than someone that makes money from you saying yes.

I wouldn't want strangers owning stuff that might get passed along to different strangers as a major structural component in my house, cost to maintain, and especially if I don't even own the power produced. I can't fix my roof, I can't replace the panels, it seems like a very tough sell without a track record. I don't think anyplace had that track record five years ago.

This would be more palatable than "We're going to install these panels after you buy then and provide x warranty". I've had 3 solar companies come give us prices on our house. If the company folds/disappears then the warranty doesn't mean squat and if there is any breakage after that happens, we're likely to end up in the red.

In the Netherlands at least there are several suppliers that will lease your roof to put solar panels on it and then either give you a monthly fee or you use them as supplier and you get discount on the bill.

In Australia, Commonwealth Bank (the largest bank here) is offering a $20000 "Green loan" at 1%.

That does more or less what you're asking for I think?

One reason is issues with property ownership. In the U.K. a company could do this but if the original customers were to see the house, they’d have no legal means of compelling the new owners to take up the arrangement. At least that’s what I understand.

The plural of anecdote is not data, but I can provide some figures. There is currently a push in London to get households install solar panels, and I expressed interest in getting a set installed to our house. Sadly, the finances don't add up.

Our house is not exactly small, and optimistically you could fit 10 PV panels on the roof. At least according to the quote I received, but having scouted installations in the nearby places, 8 might be more realistic. (Shape of the roof is a factor.)

Assuming energy prices overall grow as they have over the past decade, it would take 12-15 years to break even on the installation cost. That's with 10 panels. With 8, add a couple of years. And assume there will be no additional maintenance or replacement costs to consider.

So, at least in the UK: unless you are wealthy enough to have a large house with a sufficiently large roof, PV installations are not yet financially viable. It should be better in the rural regions where houses tend to be larger. With more installation surface area available, the marginal cost of each PV panel goes down and the marginal benefit of its energy production goes up.

Hence, in the UK, for a single-family dwelling, a roof with space for 14 panels should be enough to make the installation viable. A house with that much roof surface, at least near us, starts from approximately £700k.

I too looked into this a few years ago and was quoted 11 years to get my money back... Which didn't make financial sense at the time. Perhaps if it was more like 4 years I might consider it.

The UK has a lot of cloud cover so I do wonder if we should stick with wind power which is doing really well with the off shore installations.

Plus nuclear... For the rare times the wind doesn't blow.

I suspect it's not just the cloud cover. Looking at the map, it's quite depressing to note just how high up north even London really is. Berlin, Warsaw and Amsterdam are all similarly positioned. If we pan west along the 50° north parallel, the first reasonably large city in the American continent is ... Winnipeg.

We just don't get that much sunlight throughout the year to start with.

11 years payback is pretty good when you are lucky to get 1% interest on savings at your local bank.

Also applied for local authority buy together scheme, have a south facing roof but math came out the same, around 10y payback. Was a shame as I recall number being similar years ago. Would love to get solar but need to see it down in the 5y range to pull trigger I think.

I had mine installed seven years ago and have nearly broken even just on the feed-in-tariff subsidies alone. There have been no additional maintenance or repair costs.

The unaffordability of UK property is a separate question.

That is a long time to wait for break even. I paid €3700 for 4500Wp and I expect to earn them back in 3-4years.

I’m facing almost directly south without any shade from trees.

It's possible to attach all sorts of third-party obligations onto property ownership; this is called "burdens" in Scottish property law, I forget the equivalent English term, possibly "lien" in American?

A special historical example: https://en.wikipedia.org/wiki/Chancel_repair_liability

Utility scale solar is cheaper than rooftop solar.

My favorite part of PV is that you can scale it to fit any power generating capacity, from a residential roof all the way up to a 50MW farm. It’s fairly linear, too, in terms of land usage and cost, which makes it easy to understand.

Yes, this is really the crucial thing about solar. It scales, in all directions, from small to large.

Production capacity is scaling too, though just barely at the edge of what we need. I really wish that governments would commit hard to decarbonization of the hydrogen market (including ammonia for fertilizer), through solar/wind + elctrolyzers. The only thing stopping further scaling of production capacity is the demand side of things. Having an extra 50-100 GW of solar production to decarbonize industry would really speed the climate transition. But until there's the guaranteed market for it, the market is going to develop very slowly until green hydrogen is cheaper than natural gas as an input.

Germany pushed solar along when it wasn't cheap, greatly accelerating the fall off solar prices. All governments should push industrial chemical process decarbonization together.

The other thing to is the massive redundancy with solar. Friend mine worked on installing a giant GE Gas Turbine for a power plant. They fired it up and it threw its blades. And it was down for 9 months. Doesn't really happen with solar.

This means PV can be installed with some level of sloppiness and inattention to detail that would be ruinous on a large integrated power plant, like a nuclear power plant. I bet this also reduces labor costs by reducing the level of training and expertise required.

My half joke is most of the maintenance work for a solar power plant can be done by two guys in an F150 pickup truck.

50MW is a small scale solar generator these days. Bhadla Solar Park is 2.2GW, and there are plans being tossed around to go even larger. For example 10GW in northern Australia (Sun Cable).

I don't think we misunderstood that part.

When people can make or save money easily, then it will sell, if they can't it won't.

So the 'tipping point' was always going to be when it became practical to industry, then business, then consumers etc..

We're still not quite there yet as it will 'really happen' when homeowners can go to Home Depot, pick up what they need and have it up and working same day. When that happens, it will Solar Armageddon, the good kind.

Unless you live in the sunbelt, it will take more than a few years to recoup. Factor in replacing the inventor every 7 years, it becomes questionable, it also depends on your storage solution or local buy back program. Add an electric car to the mix and it becomes feasible. But I think it still needs to become cheaper.

Any source for inverter life span only 7 years ?

It depends greatly on your setup but, unless you are running some crazy, completely off-grid, system with cheap batteries and cheap inverter, you can expect an inverter to last you longer than this. Most are rated for 10-15 years, with some rated for 25 year lifecycle.

As with many things, quality costs, but not all costly inverters are quality, so do your research before you buy.

The warranty for most residential solar inverters is around 10 years, though often prorated towards the end of that timeframe. 7 years does not sound crazy, though with good cooling and and decent quality it's probably a tad low.

Where are we at in 2021 for pay off period? Does it vary by region?

In Australia, after a $2500 .gov subsidy, mine will pay for themselves in 4.5 years. LG Panels with 25 Year output guarantee. 6.6kw System. Financially speaking it's a complete no brainer. One thing I did notice when I was living in the USA though, was how expensive it was over there compared to Australia. Installation costs are 3x the price, I have no idea why. My system before the subsidy was $11k, and that was for top of the line panels and inverter. Cheap panels would have been around $7k

Electricity costs are ~ $0.2 per kwh, AUD

Most of the difference is in business practices, in customer acquisition. Basically all the advertising and salespeople to push solar. Lack of uniform building codes, and highly disparate permitting processes also raise costs in the US. Utilities are also hugely inconsistent throughout the US, not varying city-to-city like permitting processes, but there are thousands of different utilities in the US each with different policies. And perhaps the biggest problem is utility policies that either eliminate or make feasible solar for homes. After a utility makes solar possible by allowing favorable interconnection policies, companies rush in attempting to take advantage of the new market. But when utility executives get enough lobbying power to make solar economically infeasible through unreasonable fees, it kills existing solar installers. So the only solar companies that survive are those with large reach across lots of geographies that also have massive marketing arms that can do big customer acquisition when there's a sudden window of favorable solar interconnection policy.

I paid €3900 for 22 panels, 7.2kw system here in the Netherlands. I did install it myself (but the whole package was delivered and the electric connections done by the supplier), and the panels and inverter are cheap Chinese brands. As I didn't situate them ideally and they lose efficiency as the heat up quite drastically I expect to generate between 4500 and 5000kwh. That should save me about €800 a year so this is a pretty solid business case.

So to me the US prices seem even more ridiculous

As an example of internationally known brand/quality, here's a complete installed 6.6kw system from IKEA for AUD$5047 (AUD$3197 after subsidy).

That includes panels, inverter, mounting system, and installation.

https://www.ikea.com/au/en/customer-service/product-support/...

At this price point, it's becoming a no-brainer.

In the U.S. it varies by region, but mid-quality panels are usually quoted at $2.50 to $3.00 per watt installed (before subsidies). Tesla Solar is advertising $2.00/watt nationwide but there are some questions about their responsiveness in actually getting anything installed in a timely manner. Outside of CA most people are only paying $0.10-$0.13/KWh making payback rough unless you have a large state or local subsidy on top of the federal 26% tax credit.

Very interesting -- currently in WA and quite interested too. What size house you're referring to?

definitely varies by region according to cost from local utility and solar efficacy.

- SoCal Edison is $0.23 / kWh. https://www.sce.com/residential/rates/Standard-Residential-R...

- Entergy Arkansas is $0.074 / kWh. https://cdn.entergy-arkansas.com/userfiles/content/price/tar...

Hugely. A few of the main factors that will determine your payoff time:

- Subsidies. - Cost of labour. How much do you need to pay to install the panels? - Your energy usage patterns. If you use a lot of energy when the sun is shining, your panels will pay themselves off faster. - Cost of transmission of energy. How much does it cost to get the energy from the generator to you. - Cost of energy. How much it costs to generate energy where you are. - Location. Proximity to the equator, annual sunshine hours, shading, panel angle.

My area has a payoff roughly in line with the lifetime of the panels themselves, or half that if you believe the local companies absurd projections of future energy prices.

In the UK it takes a while:

"The price of a typical solar panel system is about £4,800. It can take anywhere between 15 and 26 years to recoup this costs, for a typical home – depending on where you live"

https://www.moneysavingexpert.com/utilities/free-solar-panel...

The key is do you use lots of electricity during summer days when the panel are producing? If so a 5-10% return even with loss of capital is possible. If you don't consume the electricity yourself then it's not really economic. Obviously closer to the equator and higher your electricity prices the better it gets.

To install on your roof - 7-8 years in lithuania. There is a ~20% subsidy for up to 10kW systems.

Alternatively, pending a change in the law, there are solar fields where you can purchase panels (also eligible for subsidy) and pay an annual maintenance fee. In this case it is around 6-7 yrs.

Annual fees on those farms make no sense...

We've got a quote for €6k - €2.5k subsidy for 8KW system. We use a ton of power - which is a main factor how quickly you get your money back.

What doesn’t make sense about it?

We were planning to get 18kW system installed on roof, but to get sign off from power grid we would need to upgrade our power lines at great expense (we are end of line rural), so I am wondering about using solar farm for additional capacity (when it’s available).

Interested in your thoughts.

18-25 €/kw = €200 per year times 25 years = 5k€ of 8k€ install is 62.5% of your system cost... This actually buys you some off the shelve batteries (5kwh so far IIRC) which might alleviate your line capacity issue (not sure tho).

Plus they reserve right to set it whatever they want it and you have no practical way to sell your investment...

Yeah, batteries won’t cut it really - need to store thousands of kWh for winter. I’ll have to look into the terms some more - afaik nothing is finalised yet, awaiting change in law. Thanks for input!

Batteries are to get you thru the night, forget winter.

2.3k euro for 5kwh [0] which sounds more than Tesla Powerwall. You probably want more, but you do your math. Probably you'll want to return more to network in summer and use that in winter. Store peak winter excess

0: https://shop.saulesgraza.lt/parduotuve/saules-elektrines/sau...

I'm getting 8kw installed on my roof next month and the pay off is somewhere between 10-12 years. That's with NC's electricity costs being cheap at ~11c per kWh - in other areas this will drastically change.

If and only if you own the land (or enough land) to put solar collection on!!

That's NOT MOST PEOPLE. And not that many "average people".

Depends on where you live. Sure, if you an apartment heavy area like Singapore, then no - but based on some very quick googling, it looks like globally around 60% to 80% of the population live in detached or semi-detached houses, where they own the roof, so there's your free space.

Even when people rent, I can see having solar panels simply becoming factored into the rent equation. If the renter can expect to save $100 off their monthly power bill, then the landlord can easily ask for an additional $80 in rent, which means they make more profit over the owned lifetime of the property.

> There is never any skepticism about the technology, the safety, the long term impact (as you would have if someone was setting up a nuclear or gas power plant). They simply “get it”

This is also a bad thing, because there are some real issues with PV panels too: leaking toxic materials, recycling problems, environmental side-effects because you need to mine for rare earths and critical metals, etc. It's far from being as simple and as clean as many people imagine, and not taking into consideration all this might cost us all a lot of damage to nature and wildlife in future. I don't want to get into nuclear vs. solar energy flame wars here, primarily because I don't feel that I have enough information and knowledge to be able to perceive all the possible side-effects of each type of energy - but the fact that world is so deeply biased one way for solar, the other way fro nuclear energy definitely will not help the best judgment on this very important topic.

Correction: Crystalline silicon solar cells, the most popular type today, require no rare earths.

The most expensive and rare element in them is silver - used for the reflective layer underneath.

Silver is used in the front contact wires, not a reflective layer.

yes, if you don't count in the inverter and charger controller units and the batteries used as part of a common setup... I've got a degree in electrical engineering, but as I've said, I really don't feel competent enough to go into any discussion on a degree of actual threat, if any, as looking into all the side-effects of some tech is really complex task far above my pay grade and it's super easy to overlook something and jump to wrong conclusions. I just wanted to point out that this popular black & white bias between solar and nuclear is not as simple as people think of it.

Batteries are very rare as part of most residential solar installs. Inverters and charge controllers are pretty basic devices, they contain a bunch of high current semiconductors and heat sinks and fans, nothing that I’m aware of that’s particularly hazardous or unusual.

How are rare earth elements used in any of those? I think you're just repeating a propaganda lie about PV.

> leaking toxic materials

What toxic materials?

It's selection bias.

For example, the truth may look like this:

The majority of new solar panels use zero toxic materials.

Old solar panels installed decades ago had toxic materials until the introduction of a ban that banned these toxic materials.

A small minority of solar panels are thin film panels and they use cadmium.

However, since we have started with the "solar panels are bad" bias we are trying to look for evidence.

Selection bias results in a search for "solar panels toxic materials":

The problem? People are mostly getting rid of problematic solar panels in the first place. Regular solar panels can be easily recycled, you extract the glass, the aluminum, the silver, the lead free solder and sometimes even the wafers and then you are left with some residual problem materials, things like leaded solder or unrecycleable thin film cells.

Those things make the news, grab the clicks and give the appearance that all solar panels are like that, because those articles aren't there to present reality, they are there to lie by omission and misrepresent so that their readership has one more story that fits in with an overall narrative, no matter how misguided that narrative is.

Mostly the impurities coming from contacts and support materials, according to [1] primarily As, Cd, Hg, Se,Pb, Zn, Co, Ni, Mo, Cu, Cr, Sb.

"In the course of the work, it was found that the toxicity indices of the EVA and Tedlar® components increase with prolonged exposure to materials in aqueous solution, approaching values characterizing an unsafe degree of toxicity to the environment and human health."

[1] https://www.e3s-conferences.org/articles/e3sconf/pdf/2020/21...

From Wikipedia, "Swanson's law is the observation that the price of solar photovoltaic modules tends to drop 20 percent for every doubling of cumulative shipped volume." (Swanson's law is a special case of Wright's law for more general manufacturing costs, and is a misnomer.)

https://en.wikipedia.org/wiki/Swanson%27s_law

Fusion power you can install on your roof. Throw in a little storage and a decent climate and the power companies are on track to be thoroughly screwed.

>power companies are on track to be thoroughly screwed.

I have a hard time making sense of this. I log into HN and see comment after comment about how solar is taking over, then I read articles like this[0], that state that countries heavily invested in renewables, like wind a solar, are going backwards. They are now trying to label natural gas as "green investment" in Germany, otherwise they won't have energy capacity. They have to build more fossil fuel plants.

Do you really think "power companies" are "screwed"?

[0]https://www.cleanenergywire.org/news/eu-indecision-over-gas-...

Concerns about Germany’s energy system transition and the question of whether power companies are “screwed” are kind of orthogonal.

There are different kinds of power companies.

Utilities with a regulated asset base that get to socialize all of their costs across rate payers aren’t screwed.

Asset-light energy suppliers/retailers in competitive deregulated markets aren’t screwed.

Asset-heavy power generators in competitive deregulated markets might be screwed .. if they have a large portfolio of legacy assets.

Solar PV creates two problems for them.

Firstly, distributed solar reduces the load available to them to serve.

Secondly, centralized and distributed solar depress wholesale energy prices in the middle of the day (and causes increasing frequency of negative-price events).

Together these reduce the volume of sales, reduce profitability, and can increase running costs, because many legacy generators weren’t originally designed to be flexible with the ability to ramp up and down every day.

While solar PV isn’t good for some power companies, it’s generally good for consumers.

And this is why the utility companies are trying to shut it down or make it uneconomical. NEM 3.0 in CA, for example, has a rent-seeking provision where the power company gets to bill the rate-payer for assets the rate-payer owns, even if no power crosses the meter. I predict a rash of off-gridding.

The power-companies-are-screwed story is a bit oversold. The cheapest solar power comes from large solar farms, exactly the sort of thing power companies themselves build and operate. Smaller distributed solar units are a big financial winner in the following circumstances:

- If retail electricity prices are moderate/high and excess solar power generation gets a net metering credit. I don't think that this will remain common as solar penetration increases, but some early adopters in different regions will be able to take advantage.

- If the electrical companies invested too much in transmission and distribution infrastructure and are now making up for it with high prices per kilowatt hour. This describes the Australian rooftop solar boom and at least parts of California. Note that this can be a financial winner even without retail-priced net metering; you're just thrifting on how much overpriced electricity you buy from the power company.

- If the location is far from the existing grid and you're expected to pay to build the intervening connection yourself. Solar plus batteries, even with today's relatively high battery prices, can beat the cost of building that connection.

Mostly I expect power companies to survive the rise of solar power just fine. Most solar generation will come from large facilities owned by large companies, not household rooftop units. The over-representation of small rooftop solar units in Germany has contributed to the high cost of their energy transition. I see the German policy decisions favoring small solar units as a carrot used to ensure broad population support for solar power. Maybe it was politically necessary. But the generating costs would be lower had they favored fewer, larger installations.

The post you are responding to definitely wasn't very nuanced.

Considering there are so many people whose solar is grid connected you would think that they would often ask themselves how difficult it is to maintain repair and operate the grid they rely on every time it snows or rains or at night.

You don't even need a decent climate. I live in Portland Oregon where it is cloudy for 9 months out of the year. In Portland, anything we generate beyond what we can use is fed back into the grid and given to us as a credit. We generate enough solar power credits that we don't pay anything for electricity year round other than a $12 monthly fee to be tied into the grid.

If they're crediting you for that energy at anything close to the retail electricity rate you're effectively getting a really generous subsidy. Because solar is so cheap but only produces electricity sometimes and at pretty much the same time everywhere in the region, the actual cost of electricity when your solar panels are producing heavily and feeding back into the grid is much, much lower than when they're not producing and you're a net consumer of grid power. Not only that, but it's a subsidy that's likely paid to wealthy people who can afford to install solar by poorer people who can't.

These fallacies against net metering have been disproven. See the linked citation for details.

“Nevertheless, by the end of 2015, regulators in at least 10 states had conducted studies to develop methodologies to value distributed generation and net metering, while other states conducted less formal inquiries, ranging from direct rate design or net-metering policy changes to general education of decisionmakers and the public. And there is a degree of consensus. What do the commission-sponsored analyses show? A growing number show that net metering benefits all utility customers.”

https://www.brookings.edu/research/rooftop-solar-net-meterin...

That link of yours states again and again and again that net metering doesn't cost shift as if this were a general principle, but if you look at its sub resources you see support for very different conclusions, namely:

* Solar doesn't yet have enough market penetration for the duck curve to be a problem. We're still in the early days where cutting peak usage benefits everyone.

* Social good rationalizes the cost shifting

"It hasn't happened yet" and "it's for the best" are VERY different arguments from "it won't happen." Why the deception? Shifting the grid's role from generation to storage is not impossible. Barring that, distributed storage is not impossible. Making PV panels cheap was a huge but tractable step that is now behind us. Figuring out storage is the second huge but tractable step and it's well on the way to being solved. In the meantime, it absolutely makes sense to deploy PV at least until it starts cutting into base load, and from that point the economic case for storage becomes clear and obvious. The facts are on our side, so why lie?

I’m satisfied with the data and contents of the post to substantiate my assertion. You are free to cite your own sources if you disagree. I believe the Brookings Institute to be a reportable source.

My intent in no way is to deceive or put forth bad data.

Your source doesn't support your assertion, but I suppose you're free to ignore that little problem if you want to.

In the meantime, we should be talking about how best to make storage happen, because anyone who isn't busy playing semantics games can see that storage (critically: paying for storage) is going to dominate the back half of this transition.

IMO, the solution isn't storage. It's ways to use cheap energy. As solar energy becomes an increasingly large part of the grid, there are huge incentives to re-structure electricity demand around when solar is producing heavily. One possible way this plays out is that we start doing things like water desalinization to produce fresh water, and electrolysis to produce hydrogen during the day when electricity is free, and getting heavy energy industry like aluminum smelting to shut off in periods where demand is higher. Some amount of grid storage will be necessary, but I'm guessing a lot of the solution will be shifting demand rather than supply, since it's a lot easier to turn off machines than to store enough electricity to keep them on.

Two sides of the same coin, I'd say.

The claims were being made that net metering currently has a set of issues that makes the referenced policy a generous policy. The link provides seems plenty to refute that claim to me. You seem to be moving the goals posts here.

If you combine net metering with time based pricing, it seems like there is plenty of incentive for smart people like you to build energy storage and make money off of arbitrage.

There is, but storage isn't cheap enough yet. Tesla powerwalls are still pretty expensive, at around $8k each, from what I hear. If they can get the cost down by another factor of 5-10, I think you'll see a huge acceleration in adoption and possible arbitrage.

The post didn't describe net metering

edit: actually I think it did :) ignore me

Why isn't it net metering? It seems to be net metering whether you count in kilowatt hours or dollars.

They are selling back to the grid, with a smart meter that counts power in both direction. Theres many types of policies in net metering like details about what rate you buy and sell power to the utility. In some less favorable places, the grid sells you power at retail prices but buys it back from you at wholesale. In these places, to achieve a $0 utility bill you would be generating more during the day than you consume at night. If your net metering deal paid back at retail rates you may get a credit, but as far as i understand each utility can offer totally different net metering deals, if they offer it at all.

Our system generates about 10 MWh per year (10 million watts of electricity). Our house isn't that big (1800 sq feet) and we have all LED lights and the highest energy saving appliances. We don't use anywhere near that many watts in a year. Our surplus credits easily cover our energy costs during Winter.

> (10 million watts of electricity)

10 million watt-hours of electricity

Your system would produce 10 million watts if it did 10 million watt-hours per hour.

Yeah, I don’t know the right way to write it. When I look at the app the reports our solar panel output and say I just want the output for all of 2020, it reports a figure just shy of 10 MWh. The previous years were close to the same figure. How do you say what the total output from a system was over an entire year?

10 megawatt hours is fine. 10 megawatts is incorrect. It's a mistake of units. A MWh is an energy measure while a MW is a power measure. That's what the parent was correcting.

You can say 36,000 Megajoules if you prefer :-)

That sounds great. What kind of heating system?

Natural gas furnace. I probably would have gone electric if we had installed the furnace after the solar panels went in. But, our natural gas bill is so small that I don’t really worry about it.

If that furnace is "smart" enough, you could add electric heater as additional external heat source. My wood pellet furnace has such options, but I think that if I simply added some electric heater into main loop, it would just work less (it can change it's output power from 24kW down to 7kW or just turn off burner if main loop is hot enough).

Oregon's electricity is only 0.75% from solar, which should mean that variations in solar output have almost no effect on the price or production levels.

I would hope at such small levels of production, the proximity to the user would reduce power losses and be automatically corrected for by the timing generators so as to shift production closer to the user.

It does seem like close to retail rates aren't outrageous to believe are fair for small quantities. I think you'd need to get to the point where generation was a significant fraction of local usage before transmission was costly or inefficient... but by then you'd likely find batteries cheap enough to also just load shift by physically storing the electricity in small buildings around a city.

Maybe the retail rate should go down, but it does make some sense for a tiny generator right next to or even in the same building as a user should get closer to retail rates than generator rates. If enough people did it they could eliminate transmission lines entirely and just use batteries.

In oregon you can also sign up for community solar, get a state sponsored discount on your bill, and not put up the capital costs to install yourself.

https://www.energytrust.org/community-solar/

Peak solar production is in the summer.

Peak electricity demand is driven by AC, primarily when it’s hot... in the summer.

Peak solar production during the middlish periods of the day in summer. Peak demand (if your grid is summer peaking - some peak in winter) is likely in the afternoon when people get home, right as solar output starts to taper off. It all varies a bit by culture and climate, but I think this is largely true.

This pattern may have changed or be different in different states, but I did participate in a project (about 15 years ago) where we essentially agreed to offline a very significant facility including a datacenter at short notice in exchange for a rebate and capital funds.

In our case I definitely recall most of those outages happening midday as it screwed up lunch. There were other factors as well (I think transmission efficiency diminishes as you approach capacity, so localized issues are a thing)

You can easily offset that changing the angle the panels are installed at. People think in terms of maximum total output but tracking solar show significant power is available late in the day.

As solar keeps getting cheaper the question shifts further from how do I get maximum power to how do I maximize my investment. Which is a slightly different and far more complex optimization problem.

Yeah you're right. But, tracking solar (and solar with fixed positioning that maximises energy output later in the day) largely applies for more sophisticated sites such as commercial and industrial. I've seen such setups that forego around 20% of solar energy production to maximise production during more expensive time of use windows (including offsetting time of use demand charges).

Residential installations are usually setup to maximise the total output, and often the positioning is constrained by the geometry of the roof. Residential solar installers are really in a race to the bottom.

One up and coming trend which might have a significant impact on this is for residential retail tariffs to be directly linked, at 30min resolution, to the wholesale energy market prices.

> One up and coming trend which might have a significant impact on this is for residential retail tariffs to be directly linked, at 30min resolution, to the wholesale energy market prices.

From what happened in Texas recently that sounds like a nightmare for consumers. https://www.npr.org/2021/03/06/974417969/texas-wont-reduce-1...

I just signed up for amberelectric.com.au. They offer the wholesale power rate (set every 30m by the electricity market authority) and the wholesale solar power feed rate, for a $15/month flat fee.

They avoid the Texas problem by limiting the maximum rate to be no more than the government regulated "default power offer" over the entire year.

Planning on getting both solar power and a battery system in the next 12 months, changing my electric hot water to a heat pump and moving to hydronic heating and split system airconditioning.

I'm also going to install a second circuit back to my smart meter that will connect to my apartment garage space so that an EV charger can be installed in the future.

yeah - you shift the risk from the retailer onto the consumer. Usually these deals will have some kind of faux-insurance arrangement baked in where the consumer will never have to pay more than something like $300/MWh

cascadia summers hardly need AC too, it rarely gets over 35c

35 Celsius = 95 Fahrenheit for my fellow yanks. That seems like a pretty extreme line to draw for "when do I need AC".

I don't know about you, but the indoor temperature above which I start wanting AC is around 72-75F, or ~23C. Lots of the PNW gets over that for much of the summer. It didn't used to be this way, but I've wanted AC in Seattle for at least a few weeks a year, sometimes as much as 6 - 8 weeks, since 2013 or 2014. Particularly because the insulation in a lot of apartment buildings meant to make them more efficient in winter causes them to heat up like a furnace in a hot summer.

It can really depend on how much air circulation you can get. In a high rise, you will need AC, but if you’re in a house you can easily manage with open windows and ideally a fan in your roof that can pull air up and in. There are very few days even in Portland where the temps don’t fall into comfortable as soon as the sun sets.

This (not needing A/C) was true until the now-annual fires made it dangerous to open the windows.

At least by the sounds and oceans it's a rather humid heat.

AC sure is a quality of life if not a necessity of life... Though if our homes were built for this climate rather than by Californian companies using shoddily adapted designs it might be another story.

That's not true. At least not where I live in the Portland Metro Area. Mid July - early September is pretty much constantly 35+C.

I still can't make the numbers work for me, when I try, it seems like I'm always better off keeping my money in stocks and paying PGE to build more renewable generation.

I responded to someone else, but my response also fits here:

At the time we had them installed, both the federal government and Oregon had very generous subsidies.

We do have a loan to pay off the balance not covered by those subsidies, but the monthly payment on the loan is about $40 cheaper per month than our electric bill was prior to having them installed. So, even with the interest on the loan, we are paying significantly less for our monthly electric usage. Once the panels are paid off, our bill will just be $12/month.

What is your expected payback time on the investment of solar? It seems like in Oregon it will take a long time with the amount of sunlight and the relatively cheap energy costs.

At the time we had them installed, both the federal government and Oregon had very generous subsidies.

What is the ratio of solar panel area to floor area for your home?

The panels cover less than half the roof. The house is a 25x50 foot rectangle. So... Maybe 15 feet x 40 feet of panels?

Wow that's amazing. You've inspired me to look into this for my area even though I've never considered it before.

I think you underestimate how complex the powergrid is and how hard the storage problem is. Try running the numbers on how much battery you'd need to run california off solar reliably.

Global PV annual power production was at ~1800 TWhr/yr in 2019. Total global electricity generation was ~26,000 TWhr/yr.[1] If the doubling time is 4 years, it would take about 15 years (so 2034) for solar to be producing as much as the current global electricity generation. At that point, the cost will have dropped to 28% of what it is now (so let's say it's $20/MWhr now, that becomes ~$5/MWhr.

If the doubling keeps up, then solar would hit the current total world energy consumption only 3 years later (ie, before 2040). Exponential scaling is crazy. I've tried incorporating the growth rate of current demand, but it only adds a couple years to each of these dates.

[1]https://ourworldindata.org/energy-production-consumption

Let's run the numbers!

   - Every 4 years our production doubles
     - Meaning every year our production capacity increases by .5 (or 5 times every decade).
   - The first year (2020) starts at 165GWh capacity production
   - The total energy use of the world (in 2013) was 157,000 TWh.
   - Annual growth in energy demand was 40% between 1990 and 2008.
     - 20% for the US
     - 150% for China

Let's calculate solar energy generation capacity using the growth estimates provided.

   2020: 165GWh
   2030: 825GWh
   2040: 4.1TWh
   2050: 20.6TWh
   2060: 103,1TWh (estimated global demand of 400TWh by this point)
   ----
   2061: 154,1TWh

So assuming:

   - Production capacity and panel efficiency does not increase (which it likely will)
   - Solar will be the only source of energy (it's more likely to be one of a few technologies used)
   - We don't factor infrastructure changes, space or installation time.
   - We don't factor the consumers being ready for energy in the form of electricity (electrifying industry, cars, homes)
   - We don't factor in the environmental impact of producing panels.
   - We assume grid scale batteries that can handle buffering exist already and are installed

Seems like there is reason for cautious optimism. We have to see how governments go about rapidly normalising our energy usage to electricity (banning new purchases of gas cars?), upgrading infra and how they will generate the remaining electricity (LNG, nuclear, coal?).

We can expect to see our 2013 energy usage met with solar alone by 2060. Might be reasonable to use solar exclusively by the turn of the century (2100)

If the growth in energy demand continues to rise at its current levels, by 2060 we might see an energy demand of 400TWh. This indicates that with the currently predicted solar production scaling, solar can cover half of our energy requirements.

There are enormous challenges with things like rapidly electrifying the automotive industry, mining the materials required to meet our grid scale demand, fabrication of the components, integrating a technology that isn't plug-and-play compatible with our grid infrastructure and supporting an IO model from every node.

Source (I know it's just wikipedia but come on, this is just a comment on HN):

https://en.wikipedia.org/wiki/World_energy_consumption#Trend...

Is there some confusion in the units? IEA claims that global electricity production from solar is in the order of 720TWh

https://www.iea.org/reports/solar-pv

And the total electricity consumption is over 20 000 TWh/a, which, given current trends, means that 100% of current electricity consumption would be covered by solar already next decade. (You were discussing energy, not electricity, but electricity should be the smaller one)

> Meaning every year our production capacity increases by .5 (or 5 times every decade).

Change is geometric (i.e. fixed percentage), not linear (i.e. fixed number).

This gives 18.92% yearly increase (instead of .5), but 5.6568x increase in decade (instead of 5x).

By 2060 this gives 169 TWh (instead of 103), and 200 in 2061.

We would also expect energy growth to level of at US/EU level once it reaches them, there's no reason to expect Asia to sustain it's energy growth indefinitely.

Don't get me wrong: solar is still not enough, storage is big elephant in the room, and we should build nuclear yesterday. It's just not as bleak as your comment made it out to be.

When I look at this chart [0], seeing that we’re wasting about 2/3 of our energy, I expect the energy demand to drop significantly if we electrify everything and have more local energy sources.

[0]: https://flowcharts.llnl.gov/

This is a good point. Seems like there is reason to be optimistic. I certainly think it's possible for the US to be carbon neutral by 2050 - but ya'll better start banning gas cars sooner rather than later (seeing as modern cars will last 20-30 years).

Note that much of the waste probably comes from thermal / fossil power generation, which is unavoidable even in theory (cf. Carnot efficiency).

That is, unavoidable unless chemical energy is turned into electrical energy directly like in fuel cells (these have smaller but still surprisingly large losses), or the rejected thermal energy is used for heating.

With local energy sources, I meant, local renewables energy sources. So no chemical energy.

Maybe I'm misreading your numbers, but:

The total energy use in 2013 was 157 000 TWh (and it's probably <<much, much>> higher in 2021, due to China and India continuing to develop).

The additional solar power being added in 2061, by your own math, is 154 TWh.

So, adding up the whole line, that would mean that solar would still only offer about 154 x 40 = ~6 000 TWh (best case scenario) of electricity in 2061. Faaar from the 157 000 TWh used in 2013 and probably super far from what's going to be required in 2061.

Did you mess up your math?

Mining is indeed needed to produce some things. But then those things are not expendables and can be recycled after decades of use. And we're no longer mining stuff that we literally use once to burn it like oil, gas, coal, etc. I'd call that a net win.

LNG, nuclear, and coal are each way too expensive long term. With solar prices continuing to drop, this is only going to get worse. Coal is already being decommissioned in many countries. China is an exception but only because they are growing so rapidly that they can't keep up with clean energy deployments (despite having the largest deployment of that world wide). That's an effect that is short term. They actually announced their grid will be 100% renewables by 2060.

New gas plants (the least expensive of those 3) at this point don't make a lot of sense either. The investment pitch is horrible: we'll be producing energy at about 3-4x of the current price of renewables for the next 50 years. By the time those 50 years are over it might be as bad as 30x. It goes from bad to worse. Nuclear needs to get a lot cheaper to be interesting for investors.

Grid infrastructure is indeed a short term challenge. Having more solar and wind on the grid is causing grid operators to evolve what they are doing to fix that. A few decades is a long time to address issues though. Batteries and cables seem to be what is needed here. European and North American grids seem to have issues getting permits for new cables. E.g. Germany needs more north south cables so people in the south can actually use the wind power generated in the north. But putting a few hundred km of cables in place seems to be a hard problem from a bureaucratic point of view. It's not a technical problem though. We've known how to make electrical cables for a long time. Though there is of course some innovation in that space as well to enable more efficient long distance connections.

Cars are electrifying at the pace we can ramp up battery production. Even so, there are a lot of cars in the world and most of the new ones are still not electric. That will flip around towards the end of this decade. From then, decline of ICE could be pretty rapid. The cost advantages for owners will drive this.

EVs are a growth business in a covid year and are very profitable. So, car manufacturers are already going as fast as they can here. Interestingly, you see the same kind of learning effect with battery as you see with solar panels. And with wind power too. All of this combined means things could go a lot quicker than some companies hope/expect.

Grandparent wrote 165GW not GWh. 165GW is 1445TWh per year.

$0.01 per kilowatt hour

Sure, they'll get you in with the promotion prices, but as soon as fossil fuel plants get decommissioned you be sure the Sun is going to increase sunshine prices and jack up the $/kwh

Is the cost reduction empirical observation, or determined by estimates regarding economies of scale

Empirical, and it's applied while PV has fallen in cost by 2 1/2 orders of magnitude.

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