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Solar panels reduced my electric bill in 2022

mattbruenig.com

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Re: Solar panels reduced my electric bill in 2022

#461

Post by boulos »

kyriakos wrote: post #435
Retric wrote: post #430

Earlier quoted context omitted.

It really depends on what you mean by peak demand. From the grid’s perspective a home with rooftop solar has zero demand during peak solar production. However, that’s ignoring the home actually uses electricity during that period it’s demand simply isn’t something the utility can make money from. Similarly, transmission losses increase as temperatures rise which requires more production to offset those losses. From t…

Maybe I'm wrong here but everyone seems to be considering only home use. During day time there's higher demand from factories and industrial processes even if home use its at its lowest.

Hmm? Why guess? Each provider has public sites with graphs of demand and generation. Here's the CalISO one: https://www.caiso.com/TodaysOutlook/Pages/default.aspx showing a funny camel shape today of an 8AM morning peak (heating) and then a 5:30 PM peak. What we can't see is the demand that would be placed on the grid around solar noon, if it weren't being serviced directly by panels.

Industrial and commercial customers often engage in Demand/Response programs though (primarily for building HVAC), so if there's a likely residential spike, they can shed some of their load.

Re: Solar panels reduced my electric bill in 2022

#462

Post by nkurz »

scubbo wrote: post #410
singhrac wrote: post #283

Earlier quoted context omitted.

Hmm, I've never heard of such a setup, actually. Usually these kinds of generators are called "behind-the-meter" because they are literally behind the electric meter, so any generation you make is directly used by your house, and any excess crosses the meter. At least this web page (from a utility in NE-ISO) indicates that solar generation is still behind the meter even in a net generation setting: https://www.boston…

I just got solar panels installed (in Berkeley, CA). I can confirm that this setup (you feed into the grid, and then get supply back from the grid) was the primary option suggested (it was possible to request and receive a self-contained "behind-the-meter" system, but was considered unusual)

You've actually done this recently, so probably you are right, but I'm still doubtful. Are there two separate unidirectional meters involved? And the solar panels aren't hooked into your electrical panel or in house electrical system in any way? What you are describing isn't impossible, but it's an odd default, and would seem to be a terrible deal for homeowners now that net metering is being phased out. While it's usually true (especially in California) that you can't keep your house powered while the grid is down, I don't think I've ever heard of a case where all locally generated power was sent 100% to the grid. I've only heard of this being done in cases where the same owner has generation happening at a different place on a separate electric account. Can you confirm?

Re: Solar panels reduced my electric bill in 2022

#463

Post by boulos »

AlexandrB wrote: post #125
hbarka wrote: post #109

Assuming you are grid-tied, the reduction of electric bills is predicated on net metering, where the utility company gives you (ideally) 1-for-1 credit for the electricity you produce. In California, this was called NEM 1.0 and NEM 2.0. Every few years the California utilities lobby the Public Utilities Commission (PUC) to chip away at the NEM program. This year the PUC voted unanimously to cut net energy metering an…

Was the California grid always private or was it run by the state government at one point? To me it makes no sense to privatize services where no competition is possible. You just end up with perverse incentives to do stuff like the above.

In the US, a lot of the electrical grids were corporations (e.g., Con Edison on the East Coast is from Thomas Edison's company). I'd never looked it up before, but the predecessor to PG&E in San Francisco was the San Francisco Gas Company [1].

Of course, in 1896 an Edison company merged with the derivative of the original San Francisco Gas, to become San Francisco Gas and Electric. By 1905, that merged with something else to become PG&E.

[1] https://en.wikipedia.org/wiki/Pacific_Gas_and_Electric_Compa...

Re: Solar panels reduced my electric bill in 2022

#464

Post by cheald »

CTmystery wrote: post #199
cheald wrote: post #126

Earlier quoted context omitted.

Solar won't keep you online through a power outage. The inverter is required by law to cut power from solar panels when there is not power from the grid, so as to avoid feeding electricity back into the grid lines (which technicians may be working on!) - this is known as anti-islanding protection. If you want to be online through a grid outage you need a battery array.

From a circuit perspective, it seems trivial to open a switch back to the grid to prevent grid-feed, while still feeding the internal circuit that is the house. Can you help me understand why this is hard?

It's doable, but it requires a bunch of extra expensive equipment. Most people that want to accomplish that goal just install a battery array instead, since you're spending the money and it also gets you power coverage when the sun isn't shining. But the point stands that the typical grid-tied solar system just turns off when the grid goes down.

Re: Solar panels reduced my electric bill in 2022

#465

Post by byyll »

asdff wrote: post #52
perfectstorm wrote: post #25

Earlier quoted context omitted.

if you generate excess energy, can you store it for a later time when you need more energy (presumably summer time)?

While you wait decades for home battery storage technology to improve, you can make a water battery in the meantime with a few things from the hardware store. https://hackaday.com/2021/10/08/power-your-home-with-a-water...

You have to be joking, right? That's a 55 gallons of water as a battery that require 5.5 hours to charge and store 3.9 Wh of energy. Not enough to even power a 10W LED lamp for half an hour. A 10,000 mAh power bank is 37Wh.

Re: Solar panels reduced my electric bill in 2022

#466

Post by maxerickson »

caseysoftware wrote: post #336
ok_dad wrote: post #334

Earlier quoted context omitted.

That is not "net" metering, then. "Net" metering is having an import and an export accumulator meter and charging the customer for the "net" value in the equation "net = import - export". Anything else is marketing bullshit from utility industry organizations.

That's what I thought "net metering" was before getting solar too. Most don't do that. Unfortunately, billing departments run the world.

The term is sort of self defining. Of course it's not surprising that some people just ignore that it means something specific as a phrase. In my state, they don't try to call different rates for demand and generation "net metering":

https://aurorasolar.com/blog/what-to-know-about-dtes-net-met...

https://www.michigan.gov/mpsc/consumer/electricity/distribut...

Re: Solar panels reduced my electric bill in 2022

#467

Post by maxerickson »

oso2k wrote: post #261
eppp wrote: post #190

Earlier quoted context omitted.

And should a company be forced to subsidize a customer?

When said company is government subsidized said customer who is also a tax payer, yes. These companies use tax dollars for infrastructure investment and maintenance, at least here in CA.

Those investments theoretically benefit all of their customers.

The question is whether specific customers should benefit more than others, when the activity they are doing probably adds costs for the others.

The "supply" value of the electricity being generated is going to vary widely, it's not at all obvious that fixing it at the average cost of supplying residential electricity is going to benefit everyone buying the electricity (which as the volume of electricity involved becomes larger sort of becomes a requirement).

Re: Solar panels reduced my electric bill in 2022

#468

Post by 1123581321 »

david422 wrote: post #339
manimino wrote: post #302

Earlier quoted context omitted.

Cleaning panels also needs to happen periodically. That cost can be in the thousands, especially if your roof is hard to access (e.g. high off the ground). There are so many ways a rooftop solar installation investment can turn against you. If regulations change, your net metering goes away. If electricity prices drop, your ROI goes negative. Rooftop solar is a fun enthusiast project, but it's a lousy use of solar pa…

I have rooftop solar - and eventually I will need a new roof - which will require taking the solar panels off and then mounting them back on again - labor costs. Additionally the inverter will fail at a certain point and that is not cheap. Given some ballpark estimates, I do feel like it could simply be a wash financially.

How old’s your roof? Just wait until it’s time for new panels. You’ll want new panels after a couple decades and change for the significantly improved performance. Panel work will be routine for roofers in the 2030s and 2040s. If you installed them on an old roof, you made a mistake, and your municipality probably shouldn’t have approved the work in the first place.

Your replacement inverter should only cost $1-3k in present money, depending on its size. You probably have a warranty on it for the first half of your panels’ life.

You also don’t need to pay for an expensive extensive cleaning unless something goes really wrong or you live under an HOA that is hostile to solar.

By far, the biggest factor in ROI is your generation relative to your initial installation cost minus tax credits and SRECs.

Re: Solar panels reduced my electric bill in 2022

#469

Post by manimino »

metadat wrote: post #426
manimino wrote: post #305

Earlier quoted context omitted.

Exactly right. Typical solar installations keep you on the grid. And when the grid goes out, so do you. To become grid-independent adds substantial expense. Having your own battery adds another $10-20k, along with whatever costs are associated with switching the grid. Also, being off-grid is actually illegal in some places.

Why would it be illegal? Safety concerns? (E.g. freezing in Alaskan winter)

Utilities and governments tend to have close relationships.

Governments want utilities to continue working at reasonable prices, so they regulate utilities heavily. In exchange, utilities get protection against competition. This is true in many countries.

Specifically around solar, there's a concept called "utility death spiral" where more and more people opt out of the grid, causing the grid to be unmaintainably expensive. This the dream that solar conpanies tell their investors.

Power companies would of course want protection from the utility death spiral, and can often get it.

Disconnection isn't always illegal. Another form this can take is "all houses have to pay a grid fee, whether or not they are connected".

Re: Solar panels reduced my electric bill in 2022

#470

Post by Nathanael_M »

edmundsauto wrote: post #452
Nathanael_M wrote: post #39

Does anyone have any detailed, up-to-date resources for personal solar use? I'd love to learn more, in particular the cost/output/lifespan progress by time. Last time I checked in my area it seemed that you didn't quite break even, but that was a while ago and my understanding was/is very limited.

It's fragmented information due to so much lead gen content out there, which is of course all very rose tinted. /r/solar is a decent community.

Thanks!
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