We went solar and here are the real numbers (2021)
joshuatauberer.medium.com
joshuatauberer.medium.com
Though I think they are actually triple-dipping or even quadruple-dipping.
1-2. Net-metering and credits
3. Reduced contribution to infrastructure
There are times when their PV setup produces very little or no electricity at all. At those times, they are 100% reliant on the grid to supply them with all their electricity needs. A large part of the cost of electricity supply is the fixed cost of infrastructure, whether used or not, which is paid off by the variable supply of electricity. Since they are 100% reliant on the grid at least some time, they haven't reduced the need for the fixed-cost infrastructure, but have reduced their contribution to that infrastructure.
I guess this could be alleviated by capping the amount of electricity you are allowed to take from the grid?
4. Increased variability
The addition of variable suppliers like PV reduces grid stability and increases the requirements for and cost of measures to stabilize the grid. Battery backup could obviously alleviate this, but if not done carefully it could just stretch out the destabilizing events and then make those fewer events worse.
While I really, really like the idea of rooftop solar, (partial) energy independence, and a more distributed grid, I think we do have to figure these things out. I don't see how it makes sense at the moment.
True, that's why large p.v. farm should be BANNED not incentivized. But it's the opposite for self-consumption. I self consume (in France, I do not know how that's regulated in USA) meaning I have the interest to do my best shifting loads on p.v. as much as I can, as a result I reduce my total energy consumption from the grid (about 50% per year, being all electric) and much reduce my consumption during peak period when the grid is stressed. I do not reduce my demand only in the coldest part of the winter where the grid is strained due the growing amount of electrical heating but I do reduce to zero in summer where air conditioning demand strain the grid (here nights are fresh so no need to cool artificially at night) witch is a much welcomed thing for the grid. In the future IF battery prices fell here like in China I might also absorb much less for heating, so far batteries are just expensive personal backups. In the future we might add a grid scale data channel to the inverters, like the one we already have (mandatory by law) to allow the grid cutting/regulating EV recharging during peak demand) allowing to inject to the grid only when the grid like it.
At the moment p.v. self consumption IMO and IME makes sense both for individuals and for the grid. In the future we can be more integrated, but still the base is the same.
1-2. I'm not bothered by net metering. I don't think symmetrical metering is appropriate, and the difference between buying and selling price should be used to fund infrastructure contributions. I suspect it'll just get used as dividends for shareholders.
3. That's where a reserve charge would be appropriate. In case I'm using the wrong term, a reserve charge is a fee assessed to pay for excess capacity on the grid in case you cannot provide it yourself.
4. Variability is an important issue. To me, accept the variability of lots of small-scale producers because any one of them going down has a much smaller impact on the grid. A single hailstorm can take out a utility-scale solar installation. If rooftop solar is distributed over a greater geographic region and is much less vulnerable to localized damage.
However, I think we're missing an opportunity to improve local power resilience by emphasizing and planning for virtual power plants constructed out of rooftop solar and local batteries. In my perfect world, municipalities would have rooftop solar on every city-owned building where it's practical. There would be multiple battery sites distributed on municipal properties. City residents would be encouraged to put in their own rooftop solar and house batteries to contribute to the virtual power plant run by the municipality.
There would still need to be a reserve charge to pay for the grid, distributed among all the municipal residents, and then a usage charge for what they actually consume.
We used to have municipal power companies, and some communities around here still do. While they don't generate power, they do a much better job handling lines and restoring service after weather-based outages. We should look to the past to learn how to build a distributed future for renewable energy power systems.
Having rooftop solar should be viewed as analogous to having a home diesel generator (without being filthy for the environment). The goal isn't to save money by "doing it yourself at home" but there are other benefits like energy independence, redundancy, backup, etc.
The gridscale/utility market in PV is absolutely booming - "Solar and battery storage to make up 81% of new U.S. electric-generating capacity in 2024"[1] and is constrained by supply of batteries and PV panels. As someone deeply concerned about global warming, I'd rather any available PV panels be used in the most effective way to reduce CO2 emissions and that is in a grid-scale installation.
There might have been a case for direct and indirect incentives for homeowners to install PV 10 years ago to help boost overall demand for PV panels but there is no such need these days - the industry is booming and supply is a bigger issue than demand.
At home, in self consumption, we are in a small smart-grid. So we can do our best to shift loads on p.v. using the grid let's say "for the base load", as a result individually we spend less and have (in case of batteries) backups, at grid scale peak demand is less intense and happen less.
That's the "issue" with p.v.: utilities do not want semi-autonomous homes, they do want to own, leaving others with nothing but subscriptions, paid services, this is incompatible with current state of tech while the current state of tech is perfectly compatible with small scale self-consumption.
Now try to imaging a hypothetical society where people living in reasonably sunny part of earth have p.v. and batteries. On scale it's probably not doable today, but we can definitively start. We still need a grid or some other backup, but we do not need an UPGRADED grid in capacity terms because most of the loads, the biggest one at least, happen locally. Surely without seasonal storage being autonomous it's a myth, but technically we can pass most day-to-day needs in largest slice of the Earth who happen to be the most inhabited as well. This means we can converge to electricity as main energy without consuming much more than today from the grid.
Energy companies in DC, are incentivized by the govt to produce energy from renewable sources. They have to pay a penalty for SRECs they fail to produce, so they have good reason to convince consumers to put solar panels on their roofs and then buy SRECs from them at a rate lower than the value of the penalty.
Without SRECs, we would be losing money. Our SREC payouts have averaged $380/MWh over the past four years. When last I checked, this was by far the best price on offer in the US. I've seen "solar is a scam" posts across the Internet. Given the numbers, I'm inclined to believe that's true wherever SREC prices are below, say, $250/MWh.
I keep a detailed spreadsheet and have been meaning to write a similar blog post. The short story is that we have made more money overall from SRECs than from savings on our monthly bill.
SREC is one such subsidy - which looks enormous, twice as big as the actual retail cost of the electricity! - and the author also mentions a federal tax credit for 26% of the cost.
Note that net metering is yet another subsidy. Try to sell electricity on commercial terms at "we will provide you with energy when it's sunny and withdraw when we want, at the same price" and see how quickly you get laughed out of the room. Granted, in a climate like DC peak usage (AC) is pretty close to peak solar production so it's not quite as bad as that, but batteries cost order-of-magnitude the same as solar panels, and this is asking the grid to serve as a giant battery.
All these subsidies have clearly had a positive effect - rooftop solar is better than none at all, and perhaps there are some secondary benefits in job creation, environmental awareness, etc. But this is one area where the tax breaks would have been more efficiently spent enriching big businesses rather than sent directly to middle-class home owners.
By not using expensive land (since it's on top of a building that existed anyways).
My understanding is that in the DC case, the SREC values are anchored by DC's Solar Alternative Compliance Payment (SACP). This is a penalty energy companies must pay if they don't produce their quota of SRECs. Currently, the penalty is $480 per SREC, so the energy co.s save some money paying $350-400 vs. the penalty.
In tandem with this, DC is small, meaning rooftops are really the only place you can put panels, and DC requires that the SRECs are generated by systems located in DC:
"The D.C. City Council passed a law in July 2011 preventing out-of-state systems registered after January 31, 2011 from participating in the DC SREC Market, further limiting supply."
Source: https://www.srectrade.com/markets/rps/srec/district_of_colum...
This program has benefited me and other DC residents individually, but I would be much more at ease knowing that this is actually globally good policy. I'll admit I don't really know.
I don’t understand how not everyone can be on board with renewable energy and EVs. Even if your country exports more oil than it produces, like USA, it can still be dependent on oil production from the Middle East due to the logistics and differences in the type of oil produced.
Even if you live ICE you should support EVs with all your heart. The less people are using oil for fuel the more gasoline the less likely it is that fuel will get more and more expensive, and the more likely it is that your country won’t be completely incapacitated when the next oil crisis hits.
Do people love so much being slaves to Middle Eastern autocracies?
In oz what's happened is the SREC equivalent is now much lower and the unavoidable network and systems costs to the energy supply company went up. It's still worth having, and if you can afford the capex then arbitrage of battery can earn higher marginal return quite aside from extending your non consumption window significantly.
V2G will be huge.
This angle isn't mentioned in the article. Overall the profitability of the installation seems shaky and depends on various government interventions that probably won't be around forever.
If we model the solar installation as a conversion of cash into home equity however, the calculus changes. You are buying home equity and getting reduced energy bills in the process. You almost certainly come out ahead, the panels are in a sense free, other than costing you some liquidity.
Googling around a Zillow study says solar installations increase the value of a home by 4% on average.
The article also didn't touch on maintenance costs.
I spent $25k to install solar in 2020 (also in DC like OP). The solar company estimated that my home value increased by $14K.
As part of the install, I bundled a "heavy-up" for $5K, which is an upgrade my house needed, but not strictly part of the renewable energy system. So total cash outlay was $30K.
I immediately got back 26% in a federal tax credit: $7.8K
So on balance, my system cost $8K cash, which was paid down by energy savings and SRECs within three years. The SRECs made the biggest impact.
I would like to see the evolution of electricity bills for people who can't afford to have solar panels since these laws were enacted.
This is good, PV panels can ammortize themselves even quicker when electricity costs are higher.
> Topping out at 56 kWh in a day is pretty good... The best summer days generate almost twice as much energy as the best winter day
It was really worthwhile seeing the stats put in order like this, thank you.
Really puts the spotlight on the technology to store the energy over longer periods (ie into the Winter). What is available on the market?
AFAIK standard home batteries empty out pretty quickly even without getting used. What about Vanadium-Redox? Hydrogen-Storage is too expensive and storying it via crypto-mining feels a bit like betting.
It'd have been useful to also share a normalised graph, sort of like "in the last 15 minutes we produced an equivalent of 6kWh". I had to infer it by counting the number of bars in a 3 hour interval.
Then ~6kWh during peak time in their peak month, seems more informative.
> Our 23 solar panels are rated to produce a total of 8.28 kilowatts (kW), but in reality energy production doesn’t get that high and maximum production is for a short part of the day. We peak at about 6.6 kW
kWh is energy, kW is power (which you probably know). The graph is in energy and you clearly computed it correctly. Just to clarify.
I use about 800Kwh per month before solar was installed and now it is down to 400 Kwh - our biggest power usage is our water heater (geyser) but that is solar powered.
Coolant is heated in vacuum tubes on the roof and then the heat exchanged with the water in the cylinder.
Drop price by 50% from todays price and ROI will look very nice, especially for houses that use air condition to cool down (or heat up) the house.
TLDR. Takes years to fix it, and only if you push pretty hard.
A powerful deflationary force that eliminates fuel price volatility and achieves efficiency gains of 75%, with paybacks in the Trillions is available to many nations right now and the main response is conspiracy theories.
It's both amazing and tragic.
The big ticket items are the two pumps, the hot water, the fridges and the aircon units.
We also have electric heaters going in Winter.
It all adds up. We do 50kwh a day quite often. Sometimes 80 in summer when all the aircons are on and the pool heatpump is too.
And then yes, you need to provide your own water pressure too.
Wait why are you running a heat pump for the pool in the summer?
Believe it or not, air conditioning systems sometimes even have to reheat the air! Sometimes you have to make the air much colder than desired just to dehumidify the air, and then you must reheat it to get it back to a reasonable temperature.
There are some cool innovations in alternatives that don’t rely on all this psychrometric chart hacking, like using membranes and dissidents to perform the dehumidification, or using direct/indirect evaporative cooling etc etc.
Edit: oh and of course space conditioning demands go up pretty linearly with total volume of air, which is in turn linear with total floor area. So could also just be a big home.
It's also amazing how so many houses in warm countries are so poorly isolated and have bad window screens to avoid the sun heat up the inside of the building.
No difference winter/summer because we have gas heating. Maybe that's where the difference goes.
I'm really curious what people's base load is though. Mine is about 300W which seems very high and I can't figure out what would be using all that power. I guess we have 3 routers, an American style fridge and a Quooker tap, but even so... feels like it should be half that.
Guess I need to go around with a power meter.
One provided by Virgin that contains the cable modem and I have to use. I put it in modem mode though because its WiFi is crap.
One main WiFi router.
One extra one we have in our garden room (main WiFi doesn't reach that far).
> American style fridge-freezers are notoriously inefficient.
Yeah, though the specs for it claim 70 W average. I guess that may be optimistic so call it 100 W. That is quite a bit tbf.
I don't know why getting two separate appliances would be more efficient?
Two separate appliances really was more efficient. The European models were vastly more efficient than the American ones (European ones were like A+ rating; American were like F with not much in between). I think the American style ones are a bit better now, though (they're probably European specific models).
They also say they consume 177kWh in a summer month which amounts to more than 50kWh per day.
A quick search indicates that 1kg of pellets generates ~5kwh. So when burning 4to. of pellets in winter that adds about roughly 50kwh per day.
When using burner tech to heat, a good way to reduce the cost and profit from pv is to add a heating rod in the buffer tank of the heating system.
We live in a complex with 84 units, each with a solar roof, outputting about 12 kWh per unit per day. Maybe the owner just has a massive house, as they are outputting about 5x as much as our 2024 solar panel models …
How much difference can that make?
Beyond the dynamics of direct irradiance, there’s also weather to consider- if you live in a significantly cloudier area (which might be possible, assuming you live in Canada or Germany/netherlands/etc based off that latitude), that will obviously affect output.
And then there is also things like building-to-building shading, in case you live in a dense area… lots of things can affect this kind of calculation.
Try playing around with the National Renewable Energy Laboratory’s PVWatts calculator:
With 3 kids and winter time for heaters I’m using ~44/day average. ~26/day during summer.
That's in Paris, France.
Even a bit of microwave use won't eat much into that budget, as it's going to be 6-12 minutes per day at 1 kW, or an average of 4-8 watts.
Heating is the much harder one to find electric solutions for, but I'm sure there are plenty of examples of the right combination of temperate climates and good insulation/insolation design for that.
So far this year, our net grid import is 3000kWh and solar generation is 2500kWh. We have a 5kW heat pump and that uses quite a lot of electricity in winter when we don’t generate too much.
Especially in the winter months when it’s blowing but not sunny. But I don’t see people selling this setup.
A fully running aircon for a single room pulls around 1kw per hour, while it usually runs about 15 mins per hour in an efficient environments, depending in temps, humidity and insulation.
Not speaking oft a whole house...