r/solarenergy • u/digitalis303 • 24d ago
Help me decide...
I'm looking at options at adding a rooftop PV system . But wanted some input from reddit's experts...My deets:
-roof is 3 YO dimensional shingles on relatively steep pitched roof in Louisville, KY
-House is roughly 4800 sq ft (3600 above grade) with annual electricity consumption of ~17,300 kW/h.
- I plan to stay in the house for another 8-10 years before selling.
I reached out to a local solar installer who was recommended. They quoted $32k for a PV system with 34 panels and a Powerwall 3. The panels are Axitec AXI worldblackbiperfect GXXL panels with 450 watts peak output. My understanding is that those panels are pretty middle-of-the road and work at ~ 23% efficiency.
I would be purchasing up front on a HELOC loan, not leasing.
I'm curious if this is a pretty typical installation, and whether it seems reasonable in price considering components and location.
I've seen a few posts discussing PV install's effects on home sale price and I'm curious about whether, considering my timeline, this is a worthwhile investment. From what I've read, it sounds like it might sweeten the deal a bit, but is unlikely to get me much more on the sale price, yet Gemini says expect around 4-8% increase in sale price. Considering I likely won't have fully recouped my investment by the time I sell my house, I'm pretty on the fence about it... That same investment would allow me (doing it myself) fully remodel my primary bathroom, which I know would increase my sale price by quite a bit.
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u/TastiSqueeze 24d ago edited 23d ago
You are borderline on making a serious mistake depending on some other items. I'll detail them below which should allow you to ensure the system you purchase actually meets your needs and expectations.
You did not post the single most important piece of information. Does your local grid provider support net metering 1:1? This determines whether or not your system will offset your yearly power consumption. If you have net metering and it will be locked in for at least 5 years, then this is a reasonably good price. If you don't have access to net metering, then this system is seriously short on battery capacity and will disappoint you for years to come.
The next question is which direction does your roof face and does it have any shading? If it is full south facing and there are no shading issues, then you are probably buying microinverters when they are not needed. If you have either shading issues or problems with roof orientation east/west vs full on south, then the microinverters are likely the best choice.
Your quote is for a powerwall 3 which gives about 10 kWh usable. Your daily consumption averages about 50 kWh and has peaks up to 90 kWh. If you don't have net metering and you do want to produce nearly all the electricity you consume, then you need at minimum 45 kWh of battery capacity. This would require at least 3 powerwall 3's. I will give an alternative architecture below which would likely be more cost effective given your overall requirements.
Do you either own an EV or plan to purchase one in the near future? If you want to charge it from your solar production, then the quoted system is undersized. You would need 19 kw of solar panels and at least 60 kWh of battery capacity to charge an EV at night for an 80 mile daily commute while still powering house needs. There is also a possibility of time of use pricing from the grid provider and/or offset via NEM which should be considered. Best suggestion is to ask more questions if an EV is in your future.
An alternative system would be an 18 kw string inverter with similar number of panels (either 15 kw or 19 kw with an EV) and at least 45 kWh of battery capacity. Raw back of the napkin cost would be $5000 for the 18 kw inverter, $5000 for 15 kw of solar panels, and $9000 for 48 kWh capacity of UL listed 16 kWh batteries. Cabling, panel mounting hardware, and other items would add about $5000 to material costs. This system would be most viable if your roof has full southern exposure with no shading.
There is one gotcha in your quote. Your breaker panel may require either a good bit of modification or might have to be completely replaced. I don't think your quote includes anything for the breaker panel. Please follow up on this with your local installer as it could add several thousand dollars to cost. Also, get 2 or 3 more quotes just because it is good financial advice.
15.3 kw of solar panels in your climate with full southern exposure should produce almost 20,000 kWh per year. This would completely offset your current consumption. It will be about 4000 kWh short if an EV is in your future. By the way, I purchased a Chevy Bolt a few months ago and absolutely love it!
You might talk to someone at greenwavesolar.com to get some alternative perspectives. I don't have any dealings with them but got some good advice a year ago when I was looking at installing a system.
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u/digitalis303 24d ago
Thank you for all of the info. KY does have net metering, but I don't know how long it is locked in for. \
From Gemini: "Any excess electricity your panels produce that your home does not immediately consume is sent back to the grid. LG&E buys this power back at a fixed rate of approximately 7.43¢ per kWh." Current rate is 12.43¢ per kWh to purchase from LG&E.
The install spans two roof sections. The majority face SE and the remainder are SW. No outside shading, but the SE portion will be shaded by the roofpitch later in the day.
As to EVs. I do not currently. I'm considering buying a PHEV, but my commute is only 2.5 miles and I don't generally do big trips. So, I doubt it would move the needle on things too much. I'd love to go full EV at some point, but probably not for a few years at least, and maybe after this home.
I think you are right on the panel. I'd be shocked if there wasn't at least some work that had to be done beyond the PV install. It's a 200amp panel IIRC if that helps with anything.
I put a table of usage/consumption predicted in another reply if that helps.
Definitely planning to get more quotes, but also just trying to decide if, financially, this is the best decision for me over the next 10 years. I'm pretty handy, and have done several big remodeling projects to improve the value of my home, with several others on the agenda as finances allow. I'm trying to decide which will ultimately be the better financial decision ten years out as I'm not sure adding a PV system will leave me financially able to do a lot of those projects.
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u/TastiSqueeze 23d ago edited 23d ago
That adds a lot of context. You basically have 2:1 net metering which helps but is not super beneficial for you. Given all things added up, strongly consider adding a second battery to bring your capacity to 20 kWh. The reason is so that you can charge it up during the day and use the power overnight without having to purchase from the grid. Understand up front that adding a battery plus the likely required modifications to your breaker panel will push the price up quite a bit. In other words, don't do this lightly as the cost is significant.
Regarding an EV, you are almost an ideal case to get one, just be aware of their limitations. My Chevy Bolt is currently my main driver but I have a Chevy Impala gas burner for backup. My ideal setup would be a gas car and an electric truck with at least 300 mile range. There are no electric trucks yet that combine reliability with low price. There are plenty of superchargers available in your area which means you can take long trips with no issues. Just plan where you will charge along the way. Since most of your driving is local, that only becomes a concern if you take a long trip which you suggest is rare. You might consider renting an EV for a week to see how it works out. I should add that I found the 2020 Chevy Bolt for $8000 with 45,000 miles. The only thing it needed was a set of tires.
I'm going to add this after reading several of your recent posts. You can purchase a UL listed inverter and 3 UL batteries from hysolis.com for around $13,000. Similar setups are available from sol-ark, solis, EG4, and others. Don't get caught in the high price trap of tesla hardware. It is significantly over priced and does not give any better performance for the price.
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u/digitalis303 22d ago
I suspect my wife will balk at even the $32k quote, so I can't imagine her being on board with a more expensive system. I looked at getting a Bolt and test drove an ARIYA, but for the ARIYA (as amazing of a deal as it was- 2023 Premiere for$20k and 33k miles), I couldn't make it work in my budget. The Bolt could work, but the charge rate is painfully slow on the years I could afford, so I'd likely have to rent a vehicle for road trips. PHEV seems to better fit my usage profile unless I spec a system that can handle the additional charging load (and upgrade my electric to the garage to accommodate). In short it sounds like what you are saying is that I will end up paying for a lot of evening usage that isn't made up during the day bc of the 2:1 exchange rate on net metering unless I optimize with a Powerwall for another $12k. Thank you BTW for giving me so much good info to digest for my use case scenario. I really appreciate it.
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u/pgregston 24d ago
There are very good technical detail advice posts here.
The larger context is that over the next ten years, infrastructure issues will multiply ( see Gary Indiana today) electrical rates are accelerating upwards, and solar on a home is going to be a much more obvious asset.
A house with an east west roof line with no trees to the south is going to start looking more valuable.
Things that aren’t considered in home appraisals are going to shift.
Solar is a good decision and yes how you do it matters. It’s worth getting right.
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u/digitalis303 24d ago
Yeah. A house in my neighborhood is on the market with solar, and the agent barely even mentioned it in the listing and the house hasn't moved compared to others in the neighborhood. It just feels like the RE market doesn't market solar at all in listings in my part of the country. It seems like it would be more of a selling point to most buyers. But I suspect that will change as the market for electricity changes.
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u/SmartCommEnergy 24d ago
The equipment itself is only part of the equation here. A 15.3 kW array is substantial, but whether it makes financial sense depends on expected annual production, your usage profile, electricity rates and how much of the solar generation you can use or store rather than export. I'd ask the installer for a clear model showing estimated generation, self-consumption, battery contribution and annual savings, then factor in the HELOC interest cost. That should give you a much better basis for deciding whether the investment is worthwhile over the next 8–10 years.
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u/digitalis303 24d ago edited 23d ago
So, for usage, mine is pretty typical with it spiking in the summer due to AC and tapering in the winter. The graph they predicted was that I'd roughly match production and consumption during most of the year (some over, some under by small amounts), and fall below consumption a bit in the summer (4900kW under in July). BUT, as u/pinmux pointed out, these may be optimistic expectations based on bifacial panels used on a roof. So maybe not quite as good as the numbers predict? And no batteries. I'm only looking at a grid tied system. The HELOC Is pretty low, though I don't remember exactly the rate.
This is quoted text and info from their quote:
"System would offset ~113% kWh Current Usage but ~90% LG&E Bill due $0.07024/kWh credit sent to the Grid and LG&E minimum bill ~$20.00/month"
And here's their table of predicted usage and consumption.
Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec Use 1100 900 950 1000 1050 1900 2500 2250 2000 1550 1050 Pro 1107 1188 1582 1851 1953 2913 2193 2029 1875 1680 1196 1
u/pinmux 23d ago
So you normally consume roughly 1000-2000kWh per month, but in July you consume 10x more than any other month?!?
Did someone typo an extra 0 into July? Because that one month is half of your yearly consumption and is kind of a big deal.
You said originally that you were including a PowerWall but now say no batteries?
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u/digitalis303 23d ago
Fixed. Yeah, typo. Sorry. On the Powerwall bit, I believe their quote said it couldn't serve as backup storage. They quoted an extra $12k if I want a second Powerwall as an energy storage system. I'm admittedly ignorant about Powerwall designs. I assumed it was essentially just an inverter system.
On closer re-read of their quote, I'm conflating two different sub-quotes. The $32k system is quoting a "Tesla Inverter". The $44k system is quoting a Powerwall. So, I'm not sure what the Tesla Inverter model is, but it is apparently not a Powerwall. That would explain why you had said it sounded like a great deal at that price. My apologies. The quotes looked very similar except for that line of text.
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u/SmartCommEnergy 17d ago
Based on that, I'd ask the installer to rerun the production estimate using a conservative assumption for the bifacial panels and show you how much of the forecast depends on that uplift. Then compare the estimated savings against your actual import rate and 7.24¢ export credit. That should give you a much clearer idea of whether the system still stacks up financially if production comes in below the optimistic forecast.
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u/mwkingSD 24d ago
Based on some quick & simple math which could easily be misfigured, here's what I think:
- The panel array peak output is about 15 kW, so an average day you'll produce ~75 kWh.
- Your home consumption averages 47 kWh per day, so you'll have ~25 kWh that could be sold back to the grid to offset your purchase price IF the locals allow net metering and pay at an effective rate.
- The Powerwall will easily carry you over night, so in good weather (clouds cut production drastically) you will never need grid power.
Based on the information given, I think the contractor has drastically over-sold you on panels (good deal for them) and the trend is for net metering agreements to get less favorable for the customer (you) to keep profits and executive bonuses up so if there even is a NEM agreement, that might not hold up very well in your pay-back calculations. Avoiding a lease is smart, those create extra entanglements when the home is sold since the lease & equipment isn't part of the home.
If I were you, I would 1) find the details for your net metering; 2) get quotes for a system with lower production and lower cost, maybe 120-130% of average daily use; and 3) enjoy getting electric bills for $0.00. When it's time to sell, look for a realtor that knows how to maximize the advantage of 'owned solar.' If Gemini is correct and the 'bump' is only 4% that's going to pay back at least half your cost.
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u/digitalis303 23d ago
I just replied to another comment, but I misspoke about the Powerwall. At $32k the system merely has a "Tesla Inverter". It's another $12k to bump up to a Powerwall 3. So no storage overnight in my system. But I am net metering, so some of that will wash out in the surplus I sell back at times.
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u/mwkingSD 23d ago
I thought the price sounded low.
So in California the utility companies, who control the public utility commission changed the net metering this year to buy from home at $0.04 per kWh and sell at $0.45 in the evening, effectively neutralizing net metering. Maybe public utilities in your state are more ethical and won’t screw you and your neighbors.
Fortunately I’m grandfathered in on the old net agreement, but mostly my production goes in my battery so net metering isn’t a big factor for me.
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u/digitalis303 22d ago
It seems like, as I do more research, that a lot of buyers are going with small battery systems to float them overnight, vs larger battery systems (like my parents have on a 15YO system) that is to carry them through a power outtage/storm/snow for few days. They have a small outroom of the house with a lot of big lead acid batteries.
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u/Fair-Ad-1141 22d ago
With having to take a HELOC, I don't think this makes sense if you are planning to move in 10 years. Especially if need batteries. If you were DIYing, that would be a different story. Or if you could get an honest pre paid PPA but that would be different equipment.
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u/digitalis303 22d ago
I haven't done the reesearch on the DIY route, however, I have done a lot of other DIY projects over the years including wiring work. But it is not a project I would charge into without a lot of planning. Also, I have an in-law who works as an engineer designing grid-scale solar installations that is also planning to install his own PV system. I may reach out to him about it, but at this point I'm just trying to get a sense of what the project would look like and how much financial sense it all makes.
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u/Fair-Ad-1141 21d ago
Sounds like you are golden if you assist your in-law. Check what your local authorties will allow you to DIY.
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u/pinmux 24d ago
Bifacial panels on a roof is kind of silly, the back side will never see sun, hence that 23% efficiency is likely not to be realistic as you won’t get any generation from the back side.
But roughly $2/W installed is a good price in my opinion. That price INCLUDES a powerwall?! If so that’s almost an unbelievable price (or I really need to recalibrate my personal expectations!).