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PaperclipPerfector  2d ago (text post)   2527 thread views

Small-Scale Question Sunday for September 6, 2026

Do you have a dumb question that you're kind of embarrassed to ask in the main thread? Is there something you're just not sure about?

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Is rooftop solar a good investment if you're a homeowner? Thinking about an install after getting a house.

As someone who does commercial solar design as part of his living, I will say this: it depends.

An important factor I have not seen anyone else mention is your roof itself. You will want to install on as new a roof as possible because it will be a huge, expensive pain to take the panels off to replace a roof and then reinstall. Big, south facing portions of roof are ideal candidates but east/west facing or not bad either.

I would check on the exact language your utility has on how the hookup has to be configured, what happens to excess power you produce, and any other shenanigans they put in. Do not expect to be able to "island" in case of a power outage unless you specifically build your system to do so.

When figuring out your savings, factor in both peak (typically the highest 15 min window of power usage) and overall kwh. Solar installations will tend to reduce your peak because they produce the most power in the hours when A/C is running, usually the biggest residential electrical load, and reduce your overall kwh. Depending on your actual billing rates, one or the other factor could dominate. Solar will not reduce any flat fees (and may add some), so you cannot just do a simple percent reduction in power = percent reduction in bill.

I did the numbers in CA a while ago, and with electricity there being very expensive and progressively more expensive as you consume more, with decent financing arrangement it made total sense. In other places where the electricity is significantly cheaper financially it probably makes much less sense, though there's the self-reliance aspect for some people too. It all hinges on electricity prices (especially pricing structure - does it get more expensive?) and what you can do with excess power - would the utility buy it? How much they'd pay for it? It all needs to be carefully calculated, solar is not at the place where it makes sense everywhere for everybody, but in some circumstances it does.

Thank you for this response. Think I will have to do some math once I own the house. My electricity in Baltimore has been ludicrously expensive the past few years, so it may make sense in the end.

Earlier this year for my house, I estimated it at about $24k to install and then $3k/yr effective revenue. You break even at 8 years and then by the end of the life (we’ll call it 24 years for nice numbers), you’ve made 3x returns. That’s about a 4.7% interest rate, which is higher than high yield savings account equivalent, but less than you would expect from the market (though it’s untaxed since it’s avoided spending).

Some things that will make your model different:

  1. What level of sun does your property get based on weather and shade?
  2. How high are your electric prices and what is your outlook on how they will move in the future?
  3. Does your locality require utility companies to buy excess power you generate? Do you get any state-level incentives now that there’s no federal ones AFAIK? Without these my estimates would be way worse.
  4. How many of your utilities are electric vs fuel (eg gas heaters, stoves, dryers, etc)? Especially important if they don’t have to buy your excess power generation.
  5. How long do you expect to be at the property? You’ll need time to recoup the cost. If you move early and sell the house, I wouldn’t count on the buyer valuing the panels at the same amount you would.
  6. What condition is your roof in?

I decided not to do it, and it wasn’t particularly close. That rate of return is only ok and I would much rather have the liquidity. I also have a low appetite for hassle, and my experience is to count on significant home renovations to always be a hassle in one way or another. If you’re in a place with favorable weather, mostly electric utilities, expect energy prices to go up, and like the idea of self sufficiency seems like a good deal then. Panel prices will probably continue to drop but installation labor costs will probably rise. I would expect overall price to go down in the future but maybe not a lot.

$24k to install

Can you break it down. Where I live this is the cost of 130Kw solar powerplant. Give or take.

I saw that a typical residential installation is on the order of 10kW of panels and costs about $3/W installed, for $30k. I subtracted a little for some incentives and assumed something a little smaller than average, arriving at $24k. A quick google suggests $3/W is a typical residential installation cost. If you say 130kW plant costs $24k that’s $0.18/W, more than an order of magnitude cheaper. Maybe you’re somewhere muuuch cheaper, or maybe rooftop solar is just really expensive/inefficient compared to just putting them in a field.

I am not in the USA. But I assume that the costs of panels is comparable. So 30kw of panels here are 5500 eur (I could probably shave 500 if I actually bother to search, this is just first google list price). Probably put additional thousand for inverter/wiring. For 10Kw the bom is probably 3k euro?

So the bom is quite modest. And I am sure in USA won't be much more expensive. So I am just wondering where the rest of the money goes.

The US (also Canada) has really large tariffs on Chinese panels -- I haven't looked lately, but I think they would cost quite a bit more than 5500 EU here.

Labor costs are much higher in the USA and permitting can get surprisingly high. And energy costs are generally lower, by a lot, plus Trumps tariffs raise panel prices etc.

You should be able to self install them. It is extremely simple.

Yeah, simple if you're already comfortable replacing shingles, splicing into your houses wiring, understand the variety of products that go into sealing a roof, and trust your work poking holes in one.

That's like 2% of homeowners. Plus you probably need an electrician anyway if you want to legally sell power back to the grid. Sure, it's doable, but it doesn't change the general accuracy of his estimate.

It gets tricky if you want to grid tie. In many places, the electrical interconnect can only be done by licensed electricians and must be certified and approved by the utility. The electricians have no real incentive to make things easy on the DIYer, especially if they are signing off on code compliance, and the utility has no incentive to make things easy on customers trying to reduce their utility consumption.

In the US nearly all the incentives require professional third party installation, also I'm not sure how easy home insurance would be to get on a self installed rooftop solar.

It's heavily dependent on where you live and the local terrain.

If your property is:

  • Flat
  • Well-exposed to the sun
  • Up to code with modern wiring

You might be a good candidate.

If possible, try to line the work up with additional major work around the roof or your wiring to save on scheduling headaches and labor.

At my house, for example, I have trees on two sides of my property and I live on a slope that obscures the sun even further. This is compounded by being a very overcast region in terms of weather. The cost of the installation would exceed any reasonable ROI until either the cost of the install dips by ~40% or I have to get rid of the trees for other reasons.

How's sunshine where you are? Does your electric company offer to buy what you can feed into the grid when you produce more than you use?

When I last checked, unless you have very favorable conditions it took a very long time to break even (I think it was 25 years), let alone beat the opportunity costs, but here electricity costs are low, sunshine is not overly abundant and long winters with significant snowfall are a concern. If I were to do it, I'd do it in a limited capacity for redundancy in case of outage, to keep the lights, refrigeration and secondary heating going. But a generator and batteries are likely a more financially reasonable way of achieving this, if perhaps not quite as appealing to my preference for self-reliance.

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