a lot of people install solar on their rooftops. Much of the time this is done with the assumption that it will pay off financially because energy prices are currently at a certain rate and will continue to rise.

But here’s my question: If its financially advantageous to install solar on your roof, wouldn’t it be greatly more financially advantageous (given the main cost for solar installation is the labor) for energy companies to install solar at scale? And if that’s the case, wouldn’t the energy companies eventually do this, which, given macro market laws of supply and demand, would eventually cause the price of electricity to go dramatically down for their end consumer, thus eliminating the financial benefit of privately installed roof top solar for homeowners?

I live in the southwest, and based on online calculators it "makes sense" from a 10 year outlook to pay the money now and install solar on my home, but that’s only if the energy prices don’t fall. But nobody seems to even think that’s a possibility.

You are correct, according to National Renewable Energy Lab (NREL), rooftop solar is over twice as expensive as utility scale solar[0]. The NREL estimate is helpful in that it details the components of the cost. And, as you would expect, the hardware and labor costs are lower for utility scale because of, well, scale, but the dominating difference is soft costs (land, marketing, profit, overhead, etc). Its worth noting, soft costs for residential solar are significantly lower elsewhere in the developed world (DE, AU) mainly because permitting and marketing are much easier.

[0] https://www.nrel.gov/news/program/2018/costs-continue-to-dec...

It suggests there may be an opportunity for a company to push rooftop solar for big strip malls and other large footprint single owner buildings - they aren't utility scale, but the install efficiencies make them pretty competitive.

The incentives would be tricky, since the owners are less likely to be paying for utilities than the leaseholders...

The problem with commercial solar is the cost of the financing. Home solar is on par with a car loan, banks know how to do that with personal credit scores. Utility scale solar is the realm of private equity.

Something like a strip mall is a weird in-between that requires enough manual review that the cost to do all of the risk analysis that financing requires kinda outweighs the potential returns. Will that KMart or Costco keep that store open for the duration of the project? What happens when the tenancy changes?

I don't have any relation with Wunder, but from my understanding of them, they built some stuff to streamline all the financing and permitting required of commercial-scale to make those projects pencil out.

This is precisely the genius of SolarCity: they were able to use the low interest rates banks would charge them to install solar power on people's houses at a much lower cost of capital than the same banks would have charged the same homeowners without SolarCity's intermediation.

That sounds like a pretty interesting pitch as a business model.

But if I recall correctly, SolarCity failed and had to be bailed out by, um, Tesla. Why? Was the free money just not enough?

PG&E currently has 2.4% bonds out. Better than what you can get, but not lower than a mmf (usually less than a percent).

As a rule of thumb, rates won't sink lower than ten year tnote rates. Nobody will purchase a bond from a company that has a lower rate than a tnote.

I've heard they also believe if electric cars get going they can offer free recharge with people buying xx dollars of groceries.

But even used solar panels will be in demand.

https://fortune.com/2018/12/06/california-solar-panels-new-h...

Maybe not as cheap as large-scale solar, but cheaper than natural gas?

I'm having trouble making sense of them in terms of the cost differential between something like (say) a coal fired electricity plant (and/or nuclear) including (say) 20 year running costs, vs a solar & battery power plant of equivalent scale including the cost of purchasing the land required to build each. There may be better comparison assumptions, maybe lives of plants are different for example but I think that would be a good place to start looking at a comparison. Is per watt DC the right measure? (Probably it is but I'd like to see the justification, given the use of high voltages at scale - again I'm not the expert to know.)

One would assume from there for a power generating utility company the cost of sales, marketing, billing, etc would all be the same regardless of how you generate it. Entirely separate to that one could estimate the additional goodwill available for solar over coal or nuclear in advertising "we're clean, we're green, just look at our stunningly beautiful field of photovoltaics." Which must have /some/ value.

I wonder if the sun-chasing required in choosing the location makes getting the power from the plant to the grid more expensive? Numbers would help.

I'm also having trouble making sense of the listed "soft cost" numbers for residential. Land is already purchased so cost is zero, use what you generate so sales also zero, zero tax, zero net profit and nobody values the overhead of their time for these things, for which assumptions are critical if you do (but definitely a nice saving on the power bill you pay with /after tax/ dollars) - These assumptions I just listed are obviously wrong in that chart but why??? No explanation for numbers that don't add up when you apply obvious assumptions about what you do know makes us all suspicious, right? They really should fix that so it's obviously right, clear, honest and direct in a field I think we can all agree is marred by a veritable mountain of BS and propaganda. I'm absolutely not saying this is BS, nor am I saying it's wrong or propaganda - just I don't understand the numbers on the chart and /can't/ from what is actually there. That sucks for me trying to understand it but maybe I'm not supposed to understand these numbers because they're designed for someone else who has the necessary context. Is providing that context too hard?

> Land is already purchased so cost is zero, use what you generate so sales also zero, zero tax, zero net profit and nobody values the overhead of their time for these things

Their basis: "We model a 6.2-kW residential rooftop system using 60-cell, multicrystalline, 17.2%-efficient modules from a Tier 1 supplier and a standard flush mount, pitched-roof racking system"

So what they've done is effectively get quotes for installing their sample system and then divide by its power output. Sales tax, profit etc are added to the bill the customer pays the installer. Other tables give a more detailed breakdown.

It wouldn't be in my country (UK).

A UK comparison would be the proposed Cleve Hill Solar Park in Kent, which will also have on-site battery storage. At 350MW it is almost as large as this LA project.

https://www.forbes.com/sites/uciliawang/2014/04/29/behold-th...

That's 2400 acres and it's up and running - so I assume permitted and connected to the grid. But I don't know the the total cost to compare things - I'd assume rather cheap, because Yuma is...not a "destination" (outside of maybe a stopover for the dunes).

So clearly it’s a very different calculation. Regardless of that generators are building large scale solar arrays to sell power to the utilities at very much lower rates than what a rooftop owner pays to generate their own power. It’s just the rooftop owner can bypass a lot, and potentially all, of the utility and grid fees which are >90% of the cost. The other thing is that many utilities are hugely subsidizing this with net metering policies, which basically means the utility is acting as a huge battery for only the grid connection fee which, depending on the market, can be as low as $15 a month. Which basically seems to make products like the Tesla Powerwalls a really tough sell. Why pay $5000 for a tiny powerwall when, assuming you want grid connect anyway, the utility will be a way bigger powerwall for free?

This is the most important factor in the whole discussion.

The electricity retailers, which consist of a call centre and a two billing systems, accounts payable and accounts receivable, buy electricity for virtually nothing, $1.00 buys them 50kWh, that's about double what my houses uses per day with two adults. edit to add: per day

I'm guessing the electricity retailers aren't making a lot of money after expenses, otherwise investors would flood the market.

How would a reduction in wholesale electricity price translate to a reduction in residential retail price given the wholesale price is already almost at zero.

Here's a link to the Australian wholesale spot price and peak price https://www.aemo.com.au/Electricity/National-Electricity-Mar...

Where I live, Tasmania, the average for 2019 is $147.91 / MWh and the peak is $163.

That works out to Au$0.163. I pay AU$0.26 / kWh, plus a daily supply charge of, if memory serves me correctly, $2.30 - this is to cover network operating costs.

That's actually a fairly reasonable mark up on the retails side of things.

That makes the other commenter's $0.02 / kWh seem fairly misleading. Maybe for some places some of the time.

It's not the highest spot price seen in the market. This time of year the east coast electricity market seldom spikes, but if you go to the historical data page you can see that in January this year the 30 minute spot price in Tasmania spiked above $2000/MWh four times (22-Jan 17:00, 23-Jan 12:30, 23-Jan 13:30 and 30-Jan 16:00).

The oven can maybe just wait a day or a week even to clean itself. It usually works fine even if partially dirty, and just causes some smell due to thermally decomposing food contamination (cheese drips from pizza, etc.).

I don't have a clothes dryer, they use too much energy. I just hand my clothes on an indoor clothes airer and blow a fan on them. I usually leave the heat pump set to 16 degrees C while I'm out, the combination of mild air temp and the fan dries most of my clothes over night anyway.

Hadn't even heard of a self cleaning over. I don't bake a lot, so there's that.

There is about ~1GWh of grid scale battery storage already deployed in the US alone. 150MW was deployed in 2019 Q1 - which represents 232% growth YoY . ~5 GWh is projected to be installed annually by 2024. [1] I think that this qualifies as proven and deployed.

[1] - https://www.woodmac.com/research/products/power-and-renewabl...

It remains to be seen if this will become a common deployment generally speaking, though with more grid scale wind and solar being built it does seem likely, in my opinion.

Perfectly smoothing the curve would require something like 2TWh (charging at 150GW for 12 hours and then discharging at 150GW for 12 hours), which would be total overkill, but every little bit can help stabilize the grid—and spot prices—that much more.

The fact that 10 years from now we could have 100GWh of storage, and adding maybe 50GWh per year is pretty awesome. Global Li-Ion battery production is forecast to be ~1TWh by then.

Between electric cars, home storage, and grid storage, chemical battery production seems like it’s turning into a trillion dollar market. Eventually we’ll add airplanes to that list!

[1] - https://www.eia.gov/todayinenergy/detail.php?id=27192

If you assume they are rationally going to maximise their profit potential then saving money isn't really in their interest even before you get into externalities that they impose on others.

Another example of this is utilities moving coal and gas plants that are no longer economic into these kind of compensation deals to they get a guaranteed profit based on what the cost to run. This is why it's estimated that closing all coal plants in the US would save 10s of billions dollars just in lowered electricity costs, even before factoring in pollution and carbon.

For info on the research "value of solar" is the general term. It varies by geography and location (e.g whether demand is growing or falling, what the other power they displace is coming from etc) but it's generally pretty positive for solar. The number is even bigger when you include things that would save customers money rather than the utility, and as regulated industries they should probably be forced to consider those costs.

But what you said and what I said aren't strictly incompatible. You could get a prisoner's dilemma type situation in which it only makes sense for you to do something if someone else is forced to do something too, otherwise they would defect and gain even more. Doesn't mean it's not economically beneficial for both.

I have no real interest in whether solar makes economic sense for a household or for a utility. It clearly is at the society level and we should be organising ourselves so that we maximise the benefit, not throwing our hands up and saying "well, if it would involve changing a minor regulation on an already heavily regulated industry, then I guess I'm going to have to choose the more expensive option instead"

But of course, you need to do the calculation for your situation.

From wikipedia

"When originally announced in 2015, two models of Powerwall were planned: 10 kWh capacity for backup applications and 7 kWh capacity for daily cycle applications"

https://en.m.wikipedia.org/wiki/Tesla_Powerwall

I take it the daily cycle applications include that functionality.

Solar needs space and it needs a way to export it's electricity to where it's needed, or to where it is stored. Places where space is cheap enough almost universally don't have infrastructure.

So large scale solar does come with large capital costs.

Contrast to home owners/businesses installing solar on 'space' already paid for (or under mortgage) and there is something of a sunk cost advantage in those circumstances.

Plus there are many reasons to install solar, not just financial. Plus incentives in many parts of the world are being removed, like no guaranteed feed in tarif rates etc. Solar is just becoming cheap enough that in pure electricity bill savings it can start to make sense.

If you think about that then the expectation is that energy prices won't necessarily increase as you mentioned, and may possibly fall under pressure from decentralised generation. Already I believe some areas force citizens to pay an infrastructure charge at a base rate towards upkeep of large scale transmission lines and base load power stations etc. So the situation is much more nuanced that your comment seems to presume.

The thing that surprised us the most when we installed our home solar system was how much cooler the house was during the summer, just because of how much the air-gapped panels on the roof reduced the heating load on the house. We noticed a significant reduction in our AC bills during the couple of months we had the system installed, but couldn't use the power due to permit-waiting.

Here's a tropical house with multiple roof layers to stay cool: https://www.notechmagazine.com/2013/09/a-passively-cooled-ho...

https://wattsupwiththat.com/2012/09/12/something-practical-n... or the paper: http://callippe.com/blog/wp-content/uploads/2012/09/ORNL_roo...

But in any case... The overall reduction in energy use was about 5% better than calculated. The article stated that this was discovered to be due to the improved airflow between the roof and panels. Because the panels are installed 40mm-50mm above the roof, they leave effectively a narrow wind tunnel between themselves and the roof surface. This means that with the panels heating up, they cause an increased airflow over the roof.

This increased flow, in addition to the panels heating up instead of the roof, was enough to further reduce the energy required to cool the house down.

You must have been experiencing the same effect.

Here's a pic with the louvres open.

https://www.archdaily.com/255208/burton-barr-central-library...

Rooftop decks being so popular now, I expect someone clever will eventually add solar panels as shades.

So the idea is already there and makes sense; it's just a matter of time for it to be adopted on the consumer home market I suppose.

Now - if they would just manufacture homes to also suit the climate, and/or position them to stay cooler in the summer and warmer in the winter, etc.

Had the dome style of home taken off, especially here in Phoenix, things would be much better, because the roof wouldn't get nearly as much sun hitting it directly as standard ranch-style homes and others currently do. Monolithic dome construction, coupled with a mostly below-grade first floor, would do wonders for heating and cooling (I know of a house almost like that up in the New River area). Add in a solar chimney with evap cooling (Boyce Thompson Arboretum used to have a demo system like this), and you'd limit AC/heatpump usage to probably 1-2 months a year.

I wish I had the money to build such a home on a decent size plot of land somewhere, but I doubt I ever will.

Better to put them out in a big barren field, fairly low to the ground.

Not really my idea by the way - I have seen a number of such projects underway on the web, and in real life.

https://news.ycombinator.com/item?id=17509166

https://news.ycombinator.com/item?id=19163235

Based on your question though, you assume that utilities are somehow optimizing to provide energy at the lowest possible price. This is not true. In the US the utility is granted defacto monopoly status in exchange for its ability to ensure that it can make the capital investments in core infrastructure without going broke. Such arrangements allow the monopoly to demand rate hikes for any pretty much any reason (even for paying of litigation judgements against it when it was found liable for burning down a town).

With the existing system, there is no future in which the utility company makes any large scale investment in renewables at scale because it doesn't make enough money on that. It is sad but it is also the truth.

When a community decides to not use the state monopoly it can act a bit more rationally, but even then you need the equivalent acreage to provide the solar.

If you force solar companies to both provide the panels and provide the wires to hook your house up the local substation and maintain those wires, well they can't do that at a competitive rate.

A year later (2016), PG&E 'retired' the E7 plan, as it was too beneficial for home solar users. We're now on the E6, which is not as good, but still better than the straight TOU plans PG&E currently offers. Next year, even the grandfathered E6 plans are going to go away, and solar customers will be on a time-of-use plan that extends peak hours until well past dark, making it again more difficult to recover solar's cost as a homeowner.

This will be able to be offset to some degree by systems like Tesla's PowerWall (I don't have one yet, will consider it in the coming years) but it's definitely a game where the utilities have a love/hate relationship with people who own their own systems.

Australian rooftop solar is less than half the US prices. A 6.6 kW system installed retails at(AUD 2700 /USD 1870) and yet we have some of the most expensive electricity in the world at USD 0.25 per kW-h. In many places, 1 in 3 houses having rooftop solar. We have over 9GW currently installed and increasing at 1.5GW per year.

All this new production is taking market share from existing generators. And if you add storage, the utilities are in trouble. Therefore, it would seem to make sense if the utilities own assets and continue to sell electricity to clients. But, it is not.

The three big electricity companies are vertically integrated. They own both generation and energy retailing. (aka Gen-tailers). If they started owning small scale PV they would be faced with devaluing their existing generation assets. Or worst the grid (poles and wires). As long as the gen-tailers can pretend that solar is "marginal" they can produce huge profits from worthless assets. Over the next few years, the companies will shut their old coal plants and go all-in on solar but the longer they delay it the more profits they make.

Eg the NSW Government sold an old coal-fired generator for $1 million, the company who purchased it revalued it for $720 million a few years later. Electricity prices rose and the Federal government removed a Carbon Tax making the plant highly profitable.

The Australian electricity market is broken and so people make rational decisions to use rooftop solar. But if the energy companies moved into rooftop solar, it would cause them problems in operations and Balance Sheet problems.

https://www.solarchoice.net.au/blog/6kw-solar-pv-systems-pri...

https://mcelectrical.com.au/blog/what-size-solar-system-do-i...

https://solaray.com.au/6kw-solar-power-system-price-output-s...

(The last one suggests that cheap 6KW systems are junk)

Is that right? Pretty sure in the US most kits that size are literally 10x that cost?

That sounds too little to pay for a decent quality system which will last 20 years. For decent components, from a reputable supplier you'd be expecting to pay around twice that.

You're also discounting the need to have power after the sun goes down. If you compare roof top to mains, you really need to include the cost of a battery large enough to go off grid, which is at least another $10k, and quite a bit more if you don't want to have any lifestyle changes.

I have a 5.5 kw roof system that I am very happy with, but I won't pretend that it replaces mains power.

I also expect to be keeping mains for a long time yet. I have a desire to make my next car electric. I used to think that the grid would go into a death spiral inches batteries got cheap enough. Now I think electric cars will save it.

I think solar and storage are the future and really want that future now, and I think you do as well. But you do it a disservice by overselling the case.

I don't think most people with solar are entertaining the possibility of going off grid. Rather they are comparing solar with net metering vs no solar. In that case, it is entirely appropriate to omit your suggested battery.

I am not arguing rooftop solar does not make sense to install. I have a system and it works for me. I think for a lot of people, especially Australian homeowners it is a sound economic and environmental investment.

No, because your local utility is a monopoly, albeit a regulated one. Local utilities may be interested in solar if it generates supply at lower cost compared to legacy sources, but the cost of supply is completely independent from the question of retail pricing. Utilities are not required to pass savings onto consumers; in markets, pressure to do so is caused by competition, which is non-existent here because the utilities are monopolies.

So the question you're really asking is whether governments will use their regulatory power over utilities to pressure them into dropping prices as their costs go down. An optimist will answer you yes, political pressure will force regulators to force the utilities to pass savings along to the customers. A pessimist will answer you no, the utilities will come up with whatever reason du jour why they can't drop prices - rising labor costs, infrastructure maintenance costs, administrative costs, expansion costs, building up a warchest, whatever, and regulators will permit them to pocket the difference. A realist will answer you with a question: given that you have a stable price on achieving certainty / stability (the cost of a rooftop installation), would you rather pay the price to get stability or take a bet and risk losing some multiple of the initial outlay in the difference over the years you'll be a homeowner?

Given that homeowners are statistically more likely to prefer stability (comes with the commitment of signing multi-decade mortgages), it doesn't take much to understand why rooftop solar is popular among homeowners. Stop wondering about how people make rational decisions and start understanding that most people make emotional decisions and then use the online calculators etc. to justify the emotional decision they made.

Even if the wholesale cost of energy drops to $0, you are only dropping about 10% of the total cost of energy.

Of course, this brings up another interesting question that has been a hot button issue; if power companies are supplying less and less power (since more and more people are getting their own power from solar), the economic model of paying for power infrastructure by paying a premium for kw/hours isn't going to work. The infrastructure cost is fixed, even if everyone is generating their own power (assuming people still want to be connected to the grid, and even people with solar generally want that). How do we pay for that infrastructure?

Power companies have tried to introduce surcharges for solar users, but that has gotten a lot of pushback because it seems to be punishing people doing the right thing. However, the alternative is to push more of the cost onto non-solar users, which doesn't seem fair either, especially since solar users still get the benefits of the grid.

It is not an easy question to answer.

If you pay a fixed price for the grid then your price per kWh goes down and it makes less sense to put solar panels on your roof because they need to beat the lower price per kWh unless you can get entirely off the grid.

But then you do have the incentive to get entirely off the grid if you can, because it gets you out of the grid attachment fee. So it justifies more in the way of batteries to avoid that cost.

In other words, it makes solar + grid attachment unprofitable, so your viable options become full grid or full independence. Then depending on which one has lower costs at scale, it either ends rooftop solar or ends the power grid.

And that could go either way. The power grid has economies of scale, but it also has transmission costs that don't exist for local generation, so which one wins?

It's residential users who usually don't have a split bill like that.

Doesn’t this contradict the oft repeated news that solar is so much cheaper than our predominantly oil generated power?

No, because the law in many markets requires energy companies to buy the net product of customer-premises solar at retail price whether or not they need it, so building more production capacity with the same basic output profile as the rooftop solar that has been deployed because of government subsidies, customer environmental concerns, and expectations of future retail price moves (and soon government mandates) would be counterproductive.

This actually mirrors my thoughts on house ownership as an investment as well.

Every house I've ever rented has been privately owned by an individual and either managed by them or a company that manages tenants for them but has no equity stake. It's always struck me that if residential properties were such a great investment, these companies would move in to it rather than give up supposedly great returns for no reason. Or large financial institutions would buy the properties and then have the rental management companies as clients rather than a host of small time investors.

Likewise, airlines use a lot of fuel. They could save money by buying fuel producing companies... but they're not in that business and don't want to worry about it. You can vertically integrate but you also have to recognise what you are good at and what you want to focus on.

There are REITs (Real Estate Investment Trusts) by the way, but they did quite poorly during the GFC in Australia at least.

Installing a small amount of solar to offset personal usage at the hottest part of the day is much different than ensuring that varied demands can be met across an entire city 24/7. This is also true on a personal scale. It is much more costly to go fully off grid, and the payoff times are much longer (if ever).

The only reason that rooftop residential solar makes economic sense is because of the way we price electricity based on consumption. Utilities are building most of the infrastructure regardless of if a handful of people using 40% less electricity on sunny days.

It is more like the supply/demand has set a price for KWs and the margin the electricity companies make on it is used to subsidize the cost of the network.

Maybe not a perfect analogy but at least for me there is a certain amount of wanting to be self reliant and personalize the system and be in control of it.

My Dads 7kw array in the south lines right up with peek demand for air conditioning. Even with no batteries it gives them a 1500w emergency output if the suns out and the grids down. If you add a battery system you can get full output and use it into the night.

The ability to create shade from the panels is often overlooked, not only are they converting 20% of the suns energy to electricity with enough air space underneath they keep rook temperatures down and reduce heat load.

Would love to see a world where all cars are electric and all parking lots are covered parking with solar panels charing the cars.

* I looked at residential solar and it looked to me like if I paid it off for 5 years at the rate that it saved me money, I would be further behind than if I had waited 5 years and solar panel prices continued to decrease. So why buy now? They decrease in value faster than they save money. It wouldn't have been a financially motivated decision.

* The solar company said they could eliminate my electricy bills if I bought solar, and they did a bunch of upgrades like improved insulation. The insulation had a much higher return on investment so I did that anyway - it's easier for me to simply need less energy than to replace all my energy sources (similar to a lot of environmental issues, IMO - we could overhaul recycling infrastructure, or I could just buy food that results in less non-compostable waste).

Also I did see some arguments against solar since they have negative environmental impact over time due to toxic elements and no formal recycle plan for all the panels 20 years later.

Based on my loan, my current cost of energy is much lower than if I bought it from the grid. (About 4-5 cents per kwh, instead of 20 cents per kwh.)

My monthly payment never goes up, but it's unlikely that my cost of grid electricity will fall below 4-5 cents per kwh during the lifetime of my loan.

Remember, the cost we pay for electricity includes the cost to run and maintain the grid between the generator (or battery) and our homes. The system in the article is a little more than 3 seconds per kwh BEFORE the costs of the grid are involved.

Usually the salesmen will quote you a cost per KWh based on the total energy generated over 25 years divided by the cost of the system. This is usually very far off (in their favor) for two reasons:

- Time discounting: at a generous 5%/year, discounting makes electricity in 20 years only worth 37.6% as much as electricity now.

- Risk: presumably, future increases in panel efficiency and manufacturing techniques will make electricity even cheaper than it is now. By signing a contract or buying a system, you're buying future electricity flows without knowing how much they'll be worth yet.

Depending on the energy generation, utility companies have long term fuel contracts which often work against long term investment in renewable energy generation. Local tax payers will have to pay for the deficit or potential contract penalties if the city reduces their energy generation requirements while still having a fuel purchase contract. That coupled with the investment cost of installing solar/wind generation infrastructure is a hard sell for elected officials who depend on short term impact to maintain their constituents happy.

There is also the question of legality, as some states have strict laws on who can generate electricity and who can store it/sell it. Typically the smaller and less progressive the region, the more likely they are to go towards the path of least resistance and just let the homeowner brunt the cost.

So some consumers install it for the long term gains without placing any bets on how local utilities will react, while others might do it as an investment on the property itself. These are just a few scenarios (without talking about commercial energy consumption) out of the hundreds being discussed.

It is becoming more common now for utilities to have energy surplus buy back programs that reduce the energy cost to the end user while they wait for the industry to progress past their latest infrastructure investment (a lot of local municipalities had huge infrastructure investments in the 90s / early 2000s that they are still paying for)

The Jevons paradox tells us that this increase in efficiency may well lead to more demand instead.

* less transition losses

* the "land" to put it on is free and not being used for anything else

That said, here in Austin they have been shifting some of the tax dollars from home-solar incentives to large scale solar farm incentives instead.

It isn't just the utility's price that can change. There can also be changes to laws regarding net metering. In fact there's loads of cases where local/municipal/state utilities will try to change the law and eliminate net metering so that they don't have to pay for residential solar.

I really think there needs to be some kind of state owned grid where market forces determine the cost of energy. Everyone who wants to hop on the grid gets a meter installed and there would be a marketplace where people would be free to pick where their energy comes from. In that way the cost of energy becomes democratized and takes power away from entrenched utilities that have every incentive to keep them in control of the energy supply and to keep the price of that energy high.

-random guess

1) Long-term climate change effects

2) To reduce the electric bill

2a) To blast the AC when the sun is the brightest.

But you also have to account for land costs, as large-scale solar installations require large fields of panels.

You also need to consider what happens if prices keep rising, because if that happens the investment is paid back sooner.

I can only speak for what I see happening here in Australia.

Energy prices in Australia have been rising rapidly for a very long time and for several reason and don't look like falling any time soon.

From here: https://finance.nine.com.au/personal-finance/residential-ene...

Residential prices increased 63 per cent since 2007 and the average household bill was about $1524 plus GST.

It is this very sharp rise in electricity price that has driven the boom in rooftop solar here in Australia.

At those prices rooftop becomes very attractive.

Many of my coworkers took the deal as it feels like a win-win for all parties. Xcel gets a great ROI curve while families feel like they can run their AC's without fear for cost or environmental impact.

Also the home owner takes on the financial risk of the install. If a utility installed on homes they would need to have a lien on the home, legal costs, marketing costs, and they would still have other risks of default.

The article mentions one place it does make sense: "Cohen and company find capacity benefits exceeding $60 kilowatt-year in the top 1% of all locations. This is about 10 times what they find for average capacity benefits. It makes sense that, for example, certain circuits are very close to needing a capacity upgrade, and that benefits would be large in these places."

As with many things, the story of home solar will likely be one of early adopters duped by bad numbers and opportunistic businesses, of jurisdictions mandating the issue and running into all sorts of unintended consequences, and a tangled web of policies enacted to fudge the numbers until the observed costs to the affected people pencil out to a socially-acceptable level of hardship or benefit.

What are you talking about? It's extremely easy to put a monetary value on it: how much rated capacity, how much exposure, cost of local electricity, and voila. It is worth the number of kilowatt hours it generates at the retail cost the electric utility would charge you.

Every early adopter I know has run the numbers. It's as easy as a simplified NPV spreadsheet.

Land purchase and annual taxes add cost. To get to the scale of 1000 house, let's just pretend you need 100 acres. So where are you going to get that much land close to people so you cheaply transport it? Also, developers will make far more from that land near a suburban neighborhood than you can as a solar farm provider meaning you would have to overpay for the land. Most solar farms you see are in useless desert land. If solar farms were cheaper and more profitable than coal plants, the energy companies would have switched years ago.

The flip side is that people installing this on their house don't have this issue. They already own the land and pay the same taxes. They also gain some level of energy independence which is important to some people. Additionally, a lot of these were installed to take advantage of generous tax breaks or other discounts. That is why one of the big hopes of SolarCity was that new construction could come with panels built in and remove a lot of the installation costs. Eventually, we'll all probably have solar shingles and this all won't matter much.

Why would you need the land to be close to people? Electricity transmission losses over 100-200 miles are minuscule, and there's plenty of cheap land in the radius of 100-200 miles from literally any point in the US.

A home system that uses its own electricity has the advantage of reducing the demand on the grid. A commercial system doesn't.

Batteries aren't cheap enough yet but when they obtain an affordable range, we might be seeing the situation that you're describing because they'd meet current regulation restrictions.

1. The cost of a solar power plant is dominated by real-estate and infrastructure.

2. Energy companies are already building large scale solar farms, and have been for over 15 years. As any non-trivial large-scale construction project, these take years to approve and execute.

3. Electricity is far from a free market. In many countries (not sure how US works wtr), there are long-term commitments from grid operators (which are commonly the state) to buy zero-carbon electricity at a set price (in short, clean energy is subsidized pretty much everywhere).

I bet that for the next 10 years, the price of energy will continue to sky rocket.

https://russell.ballestrini.net/fulfilling-childhood-dreams-...

But I'm up here at 56 degrees north, and the question is not so much power during the night as during the winter. I need the grid, and so does everyone else, and the stabilization services that go along with it. So that sets a price floor.

PG&E in California has tiered electricity costs of $0.28-$0.42/kwh

Meanwhile in other parts of the country, retail power could cost $0.06/kwh

bottom line: you are correct about utility scale power if there were a free market

If your marginal tax rate is high, rooftop solar pays off just like utility scale solar.

There are studies on mix use farmland & solar. Some crops work well. Also in some scenarios it seems as if solar farms are becoming more profitable than crops.

I would guess not because you also need to pay for the grid, and call centres for when peoples power goes down and debt collection and taxes and all the other costs of business that you wouldn't have as a homeowner.

The actual answer depends on a lot of variables, are you staying on grid, what do you get paid for feeding electricity back to the grid, grants/ tax credits.

So I don't think its impossible that roof top solar ends up cheaper, I might go further, as in the medium term (10 years) theres going to be massive capital spending on the grid, so cost benefits are likely to be seen after that point.

- the homeowner gets the usage of the roof space for free

- anything you can do yourself is cheaper than paid work

- the calculation is different. The grid provides electricity 24/7. Your solar provides electricity, when the sun shines. Your solar is on your roof top, so no expensive lines are needed. And so on. So, if you can use your own solar electricity well, it is extremely cheap, as a lot of costs don't apply.

Corporate execs and short term investors just want to line up their pockets RIGHT NOW! Fossil fuel based infrastructure has been built over a hundred years. The only thing to do to make profits is keep the machine running.

Why invest and work hard to create something whose fruits will be reaped only after they death?

This logic applies to a lot of baby boomer politicians if one cares to correlate.

It should be noted, though, that this "lifespan" generally means a reduction of output by not more than 20%, not that you are left with a pile of trash. Depending on technological development, possibly replacing solar panels by then is the economically sensible thing to do, but there is no reason why you necessarily would have to throw away a solar installation after 30 years.

A reasonable short-term goal: get 100% of US peak air conditioning load south of 37° N on solar. That's the line from the Virginia/North Carolina border west to central California.

Peak solar power output and peak air conditioning load line up pretty well, so that doesn't need storage. Storage is more of an issue for wind, which varies about 4:1 over a day over large areas and doesn't match load at all.

Is it though? I imagine your landlord doesn't think it's good for them. It's not bad for them, but why would they spend hundreds or thousands of dollars improving your apartments insulation when it costs them nothing to keep the poor thermal in place.

I too lived in rentals that had terrible thermal protection. It was awful to heat and cool. Yet, my landlords wouldn't have spent a dime to improve that.

Not sure what can be done here, but with seemingly more and more homes becoming rentals this perhaps needs a solution.

A 50/50 split might work, since landlord is responsible for energy efficiency of the home and the tenant is responsible for setting the thermostat sanely?

2. Set up Bitcoin mining rig

3. Profit, since you only have to pay half of the utility bill

I think some of the Scandinavian countries have banned these heaters.

Tax based on efficiency. Tie permits for building renovation to insulation upgrades.

http://eyeonhousing.org/2015/08/the-aging-housing-stock-2/

But most energy losses in older buildings are from leaking air not thermal conductance. So upgrading to R-1 but sealed and we'll installed Windows can do a lot without having to spend 50k.

Also, you can use thermal shutters that have MUCH higher R-value than even top of the line windows.

Do you think attic air sealing, or more effective attic insulation would have a big impact? It does feel like the roof turns into a radiant heater in the summer.

(The only energy auditor available in the area is also in the business of providing the insulation, which is why I’m skeptical.)

If you have a really old house make sure you don't have vermiculite insulation which might make things way more expensive cause it likely has asbestos in it. Apart from that you can also DIY it but it's messy. Your state may offer incentives for doing it too.

https://www.energystar.gov/campaign/seal_insulate/attic_air_...

You'll still want insulation on the floor of the attic space, and seal off the living space from the attic.

From what I gather the main complication is keeping critters out while opening your attic to a substantial flow of fresh air. A pile of rockwool insulation sounds like a hell of a home for many small mammals, and bees can get past all but the finest of screen meshes. It seems feasible to diligently install screens on all the vents but it'll be a maintenance burden to keep them intact as the years go by.

I heat to 18oC in winter (Montreal) and AC to 24oC in summer. My electricity bill averages USD$40 per month. The windows made a nice difference, and still seem efficient after 10 years.

In the desert by me people use substantial awnings on the exterior putting the windows in shade. It's a lot cheaper than fancy window treatments and in my experience far more effective. Provides more space to mount solar panels too.

A well designed awning lets in more light in winter, giving you solar gain when you want it, but provides extra shade in summer.

I know a lot of people who upgraded windows & insulation.

Many also did geothermal heating. I've heard from some trades people a lot of negatives about this one though.

There's the problem.

The article says UK but it's actually EU.

As with most things, make it a legal requirement.

Forcing existing landlords to retrofit to new building standards isn't even done for safety purposes, so it certainly isn't going to happen for energy efficiency.

And calling for this to now be a thing, well, I can't think of a better way to get entrenched interests to suddenly lobby hard against every single new building reg.

(I wonder if there is a study on house sturdiness and longevity in Europe vs USA - there seems to be a huge difference. Are US houses considered a single generational (to be bulldozed instead of inherited)?)

I have lived in building <10 years old where a breeze blows through closed windows.

The energy bills aren't so bad that middle-class renters are going to differentiate which apartment they choose based on the potential energy bills. (Whereas a homeowner who has already settled down into that house/condo has an incentive to reduce bills). So the heating/cooling energy is just going to keep getting wasted.

A house I was renting took about 50,000+ BTUs worth of two large AC units to maintain around 90F during the summer. Our electricity bill would get pretty close to $500/month if it was hot (and down to <$20 other months).

It was a house with a large, north/south-facing roof, with black roofing tiles, zero roofing insulation, and poor airflow (but lots of leaks) so we couldn't just open windows/doors. It was utterly absurd construction at even a glance (outside of fashion), and our utility costs were far more than it would've cost to improve. But the property owner lived elsewhere and had no interest in improving anything, only basic repairs.

The house my dad grew up in he no a/c. We had to install it in the 1980s. Now it would be unlivable without.

But the thermal profile is terrible. It’s designed to bring heat inside year round.

10 degrees plus in changes over a few decades?

https://youtu.be/t4OET7b4ZgI

Besides the near absence of insulation, a lot has to do with design itself. Prevalence of huge windows or glazed curtainwalls, indoor convection, exposed floor slabs, huge balconies, abundance of complex shapes, and no avoidance of West-East orientation.

In general, yes, but if you look for a term called the duck curve which characterizes that frequently the load comes up after peak output, or even after sunset. For coastal CA wind often helps fill that offset as winds frequently come up near sunset, but it's not always a guaranteed thing.

So there does need to be some sort of offsetting storage - even if it's fairly short term. But, that gives us a nice set of market niches for renewable storage to grow up though with early smaller uses growing to larger uses. ie. peak offsetting for daily variation at small capacity, to larger uses of multi-day/weekly variation compensation, maybe extended weather variation offset, to massive uses for scales like seasonal offset.

https://en.wikipedia.org/wiki/Duck_curve

PS: and oddly enough, some of the old recommendations for efficiency are backwards for a newer renewable grid: e.g. getting a thermostat that schedules lower temperatures into the evening can push power use to later, vs pre-cooling during the day when you might consume the electric coming off panels w/o the need to store it in a battery.

https://www.iso-ne.com/isoexpress/web/charts

As an individual then yes you can reduce your peak load on the grid by reducing power in the evening. But that is only the case because other people have already massively reduced the peak during the day by installing solar, see this graph they provide:

https://www.iso-ne.com/about/what-we-do/in-depth/solar-power...

What I think. Demand metering in a solar grid would likely motivate people enough to cut late afternoon and early evening usage. So I think policy and rate setting can match infrastructure and it's costs to demand.

The demand isn't greater in the evening, the relative demand, after you subtract all the energy provided by solar, is in the evening, during periods of the year when demand is low but solar supply is high.

It's like someone cured cancer and then someone came up with the llama curve, showing that some of the people who survived cancer got pushed off cliffs by llamas ten years later and everyone was like "Oh no, that cancer cure has caused the llama curve, what will we do?"

But some of that capacity is slow to respond and need time to ramp up, which may be longer than the time taken for solar to ramp down.

The simple solution to this is to start those slow to ramp sources a little earlier and throw away their excess energy output.

Obviously that's wasteful, but as long as the generation mix is overall cheaper and less carbon intensive with solar added, which it is, then it's not a big deal. And obviously as soon as you add storage then they can help these sources ramp more efficently at first and expand to replace them entirely over time.

All in all it's one of the least problematic problems that ever got its own name.

What's terrible is that PG&E charges the end customers $0.28-$0.42/kwh even though it purchases even the most expensive wholesale power below 5c/kwh

I spoke with my legislator about this and he told me (and I quote) 'the PG&E lobby is strong' before ignoring me.

Typical PG&E delivered power rates are $0.28-$0.42/kwh.

PG&E charges about the same for transmission and delivery that providers outside California charge for transmission delivery and the power itself.

With just about every other commodity (and even with electricity in other parts of the country), you are given a discount if you purchase more. In the case of California, the regulators have been influenced by PG&E and have terrible pricing and tiering.

It's worth noting in Santa Clara, CA, the local power company Silicon Valley Power prices their electricity about .10-11c/kwh.

(without an existing cool place to dump heat, you can't generate energy, otherwise you could just extract heat from everything everywhere and cool it all down to absolute zero, solving both the energy problem and global warming with a single stroke)

https://www.technologyreview.com/s/608840/a-material-that-th...

It's possible to use solar heating to directly power indoor cooling, without converting to electricity as an intermediate step. My rough understanding is that this is potentially more efficient, but it adds mechanical complexity and loses flexibility (since it only really works in direct sunlight). And it's probably becoming less cost-effective in comparison as PV prices continue to drop.

Ammonia absorption does not require violating the Third Law as some commenters have suggested below. It is less efficient than the Carnot limit, so you cannot use it to get a perpetuum mobile.

To get energy from heat, you need a hot end and a cold end. The more difference between the two, the more energy you can extract. Extracting energy from small temperature differences is very inefficient. Temperature is measured from absolute zero for this.

Lower temp can only be viable if you reduce the work needed to run the engine, and can still output the needed work/energy.

This is related to why work and heat are both measured in joules.

Gas burns at a much higher energy than steam, so it's much easier to extract more energy with less fuel, making for a smaller form factor.

I should clarify I was talking about an engine here. Not a power generator.

What I said is correct though. You can compensate for lower temperatures with a more efficient engine & energy conversion, and of course more fuel/input.

The actually relevant distinction is that gas turbines, like other internal combustion engines, have a much higher ramp rate than external-combustion engines like a steam turbine. This makes "peaker" gas turbines a crucial resource for establishing power grid stability.

https://en.m.wikipedia.org/wiki/Geothermal_heat_pump

They make this sound like a lot but that strikes me as actually pretty cheap. I don't think that number can be right.

Edit: I mean seriously think. The F-35 has cost us 1.45 trillion dollars so far.

That's roughly 1/3 of the price they're asserting here. Localizing our entire energy dependence has got to have some serious national security benefits. I mean way beyond the simple evolutionary next step of one piece of military equipment.

It seems like every dollar we spend on energy sovereignity is doing like 10 or even 100 times the work 1 dollar of weapons development is doing to secure our country.

It's estimated that we spent $6.8T between 1976 and 2007 on the US policy of always maintaining an Aircraft Carrier on station all day every day in the Persian Gulf, to insure the free flow of oil.

https://offiziere.ch/wp-content/uploads/US-miiltary-cost-of-...

Or, somewhat less cynically, protecting our soft petro-underbelly from harm.