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Comment by IvanK_net | Hacker News Reader

I have always been a huge fan of a quick transition to sustainable energy sources. There is just one little thing I don't understand.

Why they expect people to make electricity at their homes? You can buy a little piece of land in a dessert, put solar panels there and distribute the electricity to other places. And you don't have to climb on any roof during the installation or the maintenance.

It is not profitable today in a free market to bake your own bread or to plant your own vegetables. Because if it is done in a large scale by professionals, it can be made much cheaper while keeping the good quality. So I don't understand, how the home-made electricity could economically compete with the professional energy farms of the future.

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Not an expert here but a couple things come to mind.

From an environmental perspective, it is better to use surface area which is already built up than pristine natural desert land. The house itself already imposes an ecological cost. A solar roof adds around zero to that cost.

I've heard the stat thrown about that 50% of energy generated is lost to transmission. If that's true then there's efficiency to generation at home.

It probably doesn't figure into anyone's decision but decentralized generation leads to a more resilient "grid". As it stands we are potentially vulnerable to warfare/terrorism attacks on the grid.

Tesla the consumer brand is about being smarter than your neighbor. Wow you have a car which is electric yet more performant than my car? Wow you have solar panels and the aesthetic is better than mine? Wow you're completely off the grid? So much material for dinner parties. In short there is a good value of cool factor for amount of work. And there are people who break the market logic and bake their own bread, plant their own vegetables.

You're right that power from a solar farm will be an option somebody but for many people it's not an option yet. This is something you can do in the near term.

> I've heard the stat thrown about that 50% of energy generated is lost to transmission. If that's true then there's efficiency to generation at home.

It's more like 5%. The larger numbers you're thinking of might be including generation losses. Coal plants are around 33% efficient in terms of converting the fuel's energy into electricity. Natural gas is better, but still under 50%.

https://www.eia.gov/tools/faqs/faq.php?id=105&t=3

https://www.eia.gov/tools/faqs/faq.php?id=107&t=3

Decentralized solar generation helps the grid in some ways but hurts it in others, specifically the need for sundown peak generation. See for example the "duck curve" problem that CAISO is facing: https://www.caiso.com/Documents/FlexibleResourcesHelpRenewab...

Only if you don't have batteries at home. Tesla promotes buying the roof with a battery pack which would allow you to use evening energy by battery and charge overnight (good for the grid) for the morning peak.

It's the right question to ask.

Home electricity costs around $0.15/kWh, while power plants sell electricity to the grid for around $0.03/kWh. The difference pays for installing and maintaining the grid and local distribution wires to your home. Depending where you are (I live in a forest, where a tree falls on the power lines a few times a year and they have to send out guys in a bucket truck to fix it) it's expensive.

Because of net metering, home solar panels effectively get paid the home rate. It's kind of unfair. If you have enough solar panels to zero out your home bill, you're getting something valuable (reliable nighttime power) that cost money (to install and maintain the wires) for nothing. But that's the system we have.

Sometime before we hit 100% solar power, the system will have to change.

Speak for yourself. My home electricity costs right around $0.30/kWh. If you can't get a net metering contract, it's already about cost-effective to just go off-grid.

The economic calculation for one of these roofs probably looks very different depending on where you live.

Not necessarily - my home was built in 2013, with a metal roof and 5kW PV system. But because it's so efficient, I end up not just zeroing out my bill, but giving power to the grid for free (since I don't actually get paid for the power I generate, I just get credits). I have evened the odds out now to some degree with a plug-in hybrid, but I will have to see if in practice charging it will soak up some or all of the surplus I was losing...

When home solar installations send excess power to the grid, they also do it in the middle of the day, when wholesale electricity prices are at their highest.

For now. When 10% of people have panels, that won't be true anymore.

So cheaper prices at the time of most usage (and previously highest cost to generate or consume) which is yet another positive externality of solar power.

If you live uphill from work, then that car just might help to balance the load. Early in the morning, you leave with a minimal charge, and roll down to work on regenerative brakes while topping up the batteries. After work, you spend that charge and the minimum fuel necessary to get home. You charge your vehicle in the late afternoon, not long after peak sun. Your home power controller is configured to allocate 80% of the car's battery for household usage, overnight.

If you live downhill from work, however, then the only way to use that to your advantage would be to work an evening / night shift.

There's a really great 99% Invisible episode (podcast) going over all the economics & history of net metering for those interested!

http://99percentinvisible.org/episode/reversing-the-grid/

My electric costs are 0.035 USD/kWh here in Europe (Czech Republic).

Wth is wrong with the USA? It seems like you're getting screwed over everything. 10x electricity, 100x healthcare and education - is US market really just a bunch of colluding monopolies?

I couldn't quite believe your numbers, and couldn't find any confirmation for them: http://ec.europa.eu/eurostat/statistics-explained/images/4/4...

http://ec.europa.eu/eurostat/statistics-explained/index.php/...

Hm, that seems unusually high, really wonder where these stats come from. Is every eurostat statistic distorted like that?

Here's a chart of energy prices on a Prague energy exchange, currently it's about 30 EUR/MWh = 0.032 USD/kWh. I pay a bit more than that (incl. distribution) with a good tarif (low cost broker), but even conservative people I know who don't renegotiate energy prices get about 0.06 USD/kWh incl. all distribution fees.

That said, electric distribution network in our country is probably underinvested. Is the premium you're paying in US based on distribution network cost?

http://www.tzb-info.cz/ceny-paliv-a-energii

Still seems low for retail. In Europe, the UK has very low costs with ~12-13€c/kwh, high cost countries such as Germany are more around 25-30c/kwh (taxes and renewable energy charge).

Electric rates in the US vary widely. The $0.15/kWh rate sounds like California prices, which are notoriously high compared to other parts. Less urbanized states have lower rates, except Alaska and Hawaii.

https://www.eia.gov/electricity/state/

You build a solar farm out in the desert it is up to you to maintain it and the supporting infrastructure (transmission lines).

Put a solar roof on a home and it is the homeowner's responsibility to maintain it.

There's also the values of geographic distribution:

* on site transmission cost is $0 for power used

* the effect of a man-made or natural disaster in one location is contained: throwing a breaker for maintenance at the Arizona border doesn't shutdown power across an entire region: https://en.wikipedia.org/wiki/2011_Southwest_blackout.

Many states have generous subsidies that only apply to residential/domestic energy production that don't apply to utility/commercial production, specifically there are credits and rebates for the construction cost, and the feed-in tariff system - these really shift the economics completely.

I live in western WA and I had a view to get a solar installation a couple of years ago, because despite our climate and sunshine conditions - and already having the greenest (hydroelectric and wind, mostly) and cheapest electricity in the country ($0.11/kWh) - there was a generous feed-in tariff - which meant my planned $40,000 investment in a solar system would pay itself off after 10-15 years, however in late 2015 the state decided to put an end to that and if I had the system built now it would take 25+ years to pay for itself, at which point the system's warranty would be expiring and I'd need to shell out more money to replace it.

It's because local photovoltaics can save a lot of infrastructure and can require nearly no labor.

You don't buy cold air piped from across the city, you make it locally. Why?

Cold air cannot be transported over long distances. Electricity can.

Both can, with losses and infrastructure investment. The size of those are very different, and that's why you does currently create one locally and buy the other from far.

Photovoltaics can¹ change the other side of the equation² so that locally generating it would be better.

1 - But it's not certain by any means. The current biggest obstacle is battery storage and maintenance.

2 - losses and infrastructure costs vs. gains from scale.

> It's because local photovoltaics can save a lot of infrastructure and can require nearly no labor.

No, they don't. You still need almost the entire national power grid to supply your home with night-time electricity... That infrastructure won't be going anywhere.

An even worse outcome will be every home having local power storage infrastructure. Tens, or hundreds of thousands of dollars for a power wall, or a compressed air storage system is much more expensive then maintaining the grid.

Since we are discussing Tesla solar roofs, they suggest your installation comes with a PowerWall, thereby storing power during the day to use at night. I personally don't think we are there yet, but I think the goal is that you don't need the entire national power grid just for night electricity, just a big battery.

Batteries + roof PV, is far more expensive on a per-watt basis, then a power grid + utility-scale generation.

"Just buy a $15,000 PowerWall, which you will need to replace every 10 years" is, compared to grid electricity, incredibly wasteful.

There's a reason why customers and users overwhelmingly prefer centralization, even if its harmful for them in the long-term. It's cheaper, and people would prefer it to be someone elses' problem.

Have you done the math? If net metering didn't exist, my back-of-the-envelope calculations say it would probably break even in California. With net metering, sure, it's pointless.

My parents pay $1,200/year for electricity, in a fairly large house. Given the expected lifetime of a power wall, that will eat all the 'savings' of living off the grid.

There's also the matter that if, say, 40% of the population disconnects itself from the grid, that doesn't mean that the cost of maintaining that infrastructure will drop by 60%. Someone will have to pay for it.

Where are you getting $15,000 for the powerwall? It's $5,500 for 13.5kWh, which should be enough for nighttime loads in many houses (but may require some inconveniences, like not running the dryer at night).

You are right that it does not yet work out, it's $0.17/kWh for the powerwall (assuming you fully charge/discharge it each night) + cost for panels. Given that grid-disconnected users would want some buffer, an off-grid system probably works out to ~$0.40/kWh all in for battery-stored electricity

You could save a big chunk of this by some habit changes, most of the cost comes from the batteries, so scheduling energy intensive activities to run during the day reduces your cost for them to $0.10/kWh or so.

Honestly I am surprised how close these numbers are. I initially was sure the grid would survive in cities, but now I am not so sure. In 10 years these numbers will likely be half what they are now (batteries in particular will be way cheaper). It might all be enough to kill the grid in many places.

In many places in the country, night-time usage is a lot less than daytime usage.

You don't buy cold air piped from across the city, you make it locally. Why?

In Sweden it is quite common to pipe hot air (and to a lesser extent cold air) across the city rather than each house making it locally. Once of have the basic infrastructure in place it is a lot cheaper and more efficient.

Well there's a bunch of factors. Energy distribution is not free or perfectly efficient. You are also doubling the footprint of the house+solar and land (nor it's ecological impact) are free.

Additional solar power absorbs sunlight and produces electricity. One benefit is that the house under it is cooler and needs less air conditioning as a result.

Also balancing the energy infrastructure for a state/country with significant solar/wind sources adds significant new complexity for the power grid. It's definitely most efficient to keep your homes power use off the grid as much as possible.

Additionally at least in California peak power use is air conditioning related and follows a power use curve pretty similar to solar production. So the hottest days/times have the most power generation (there's some lag). This allows the state to minimize power production only for those worst case days in late summer, which is the most expensive (power, cost, and environmental impact) power plant.

Power plants can be quite efficient if utilized 100%, but the difference between minimum power and maximum power needs can create huge inefficiencies where solar can help.

I'd also argue that adding distributed power use makes the grid overall much more robust. Earthquakes, major storms, attacks against infrastructure, etc are all less of an issue if a decent fraction of houses produce most of the power you need.

Land is expensive? A desert solar farm's value is what the panels built on it can produce. The value of your home property is that you can live on it. Adding solar panels just increases the value of property you already own (assuming you're in a sunny enough location, etc. etc.).

My guess would be this: there are large transmission costs associated with utility scale solar, perhaps home generation can be competitive when including those.

A local power company in my town does this (New Zealand) You buy a 'solar panel' and they add it to their solar farm while giving you the equivalent discount. The best thing is that if you move house the discount follows you.

That's a much better option than what my utilities provider offers. I can pay extra, and they will purchase wind energy for me (or at least claim they will). It is a lot more compelling to purchase something tangible, even if the end effect is theoretically the same.

Both approaches make sense. Large utility solar installations are a great way to generate electricity, but there are transmission losses to consider and there just aren't enough large scale solar projects yet to supply all the power that's consumed.

Rooftop solar gives you a way to be less dependent on the local utility for something you need to live a modern lifestyle. If you live somewhere where electric rates are high or power outages are common or most of the electricity comes from burning coal, you can now work around that by generating electricity locally.

It's sort of like storing a file locally versus storing it "in the cloud". Both approaches will probably work, but you might choose one or the other based on some weighted combination of reliability concerns, privacy concerns, available bandwidth, and whether you want to share the file across multiple computers or multiple users.

> it can be made much cheaper while keeping the good quality

I'll spare you the anecdata, but the choice of bread and vegetables are specifically poor support structures on which to build your argument for centralization. They can (in some cases) be made more cheaply, but the quality suffers substantially.

Electricity, while lacking the strongly subjective "quality" dimensions of food, still suffers from long-range distribution. Transmission and stepping losses (as well as transit costs) are a large portion of why we don't have just one enormous generation center for the world. There's obviously a balance, but for the cost of land and the added loss of converting solar's DC to AC, local generation gets a little more advantage.

One reason I don't see mentioned here is the element of risk. Establishing a solar farm is an expensive operation, and likely carries a lot of risk - particularly as a first mover. Contrast that with a potential ROI for home owners.

If you stay in a hot area, you're also going to save money from lower AC bills, because the solar panels would absorb some of the heat that would otherwise enter your house.

A lot of the cost and inefficiency of electricity is the storage and transmission over long distances.

Decentralization of energy generation is a very nice thing to have.

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