New panels on 12-year old shingle roof?

[Bob_in_MA]

I have what is a pretty much ideal roof, a 30+-foot stretch facing south with almost no shade. But the asphalt shingles are about 12 years old. They are "architectural" shingles, but still could need replacing in 10-15 years.

Given the cost of roofing a solar-paneled roof, does it make sense to consider buying panels now?

Thanks,

Bob

[J.P.M.]

I think one other way to look at, given the idea that a good roof will last maybe 30 years is: Under what scenarios does it make sense to replace a roof with 10-15 years of life still in it ?

Seems to me if the present worth of the projected PV production is > the amortized cost differential of the perhaps premature roof replacement, then it might be worth it from an economic standpoint. Other non financial considerations enter the calculus however and may need to be considered.

[peakbagger]

IMO, 30 year architectural shingles have mixed reputation in my climate (northern NH) on south exposures. They may make it to 30 years but are starting to show their age around 20 to 25 especially on the south exposure (unless defective North Exposures usually last the 30). The other thing to factor in is that many people are getting the advise that a roof replacement on the solar exposure side is part of the installation cost of PV. I am not an accountant so do check with yours if a reroof counts for the credit. Some folks are claiming the cost to do the entire roof (including the north exposure) in the credit and IMO that is really stretching it. If you can get reasonable color match for the replacement on the south side the, only person who might notice the color difference is a drone cam or someone checking it out on google maps.

The big liability on putting solar on an existing roof are any roofing warranties are null and void once you mount solar on it. If its a new roof and the mounts are incorporated into it by the roofer than its not an issue. I am also a strong advocate or installing ice and water shield under shingles and that obviously has to be done during a reroof.

Of course few folks live in the same home for ten years so it may be moot point. At some point it does become a cost liability as reroofing a house with solar will cost more than without but maybe that liability is on some future owner. My guess is having solar on the roof now is a better selling point than a nebulous increase in roof replacement cost in the future. Odds are AGW is going to riase the cost of electric power far sooner.

[Bob_in_MA]

Thanks for the replies. J.P.M., that makes a lot of sense. And it is only partly the cost of the roof, there is also the hassle of finding a roofer.

I agree about the shingles, peakbagger. I actually had some on a porch that were just 15-16 years old that needed to be replaced, but I suspect these weren't true architectural shingles. Luckily, the roofer replaced them gratis.

Part of the problem for me is that given my age and tax liabilities, I would be taking a fair financial risk for rather nebulous returns. Since our main motivation is simply to cut our carbon footprint, I think I might just go for one of the community solar deals. It saves you little or no $$, since you're paying the amortized cost and maintenance of the project and getting power in return. But there are no risks and no need to check figures, etc.

[J.P.M.]

Thanks for the replies. J.P.M., that makes a lot of sense. And it is only partly the cost of the roof, there is also the hassle of finding a roofer.

I agree about the shingles, peakbagger. I actually had some on a porch that were just 15-16 years old that needed to be replaced, but I suspect these weren't true architectural shingles. Luckily, the roofer replaced them gratis.

Part of the problem for me is that given my age and tax liabilities, I would be taking a fair financial risk for rather nebulous returns. Since our main motivation is simply to cut our carbon footprint, I think I might just go for one of the community solar deals. It saves you little or no $$, since you're paying the amortized cost and maintenance of the project and getting power in return. But there are no risks and no need to check figures, etc.

If you're more concerned about environmental impact than finances, vigorous conservation efforts can have a bigger impact than alternate energy, unless you're alreadry VERY conservation minded. Turning off a light or changing thermostat settings cost == zero. That's a lot cheaper than PV.

[Bob_in_MA]

Well, our carbon foot print is pretty small. We have one car that often doesn't leave the driveway for 3-4 days, haven't been to an airport in over 15 years, etc. But using electricity is pretty hard to avoid.

[J.P.M.]

Well, our carbon foot print is pretty small. We have one car that often doesn't leave the driveway for 3-4 days, haven't been to an airport in over 15 years, etc. But using electricity is pretty hard to avoid.

It's all relative.
How small and how hard ?? (not a question relating to anatomy)
Not bragging but I use about 7,000 kWh/yr. before any reduction for PV contribution.
I currently live in a semi arid and warm S.CA Climate in a 3,200 ft.^2 house built in 1980.
during over close to 14 years in this home I average 786 kWh/yr. A/C use and don't cook or freeze myself doing it.
The average in my HOA of what are typically smaller homes is about 17,000 kWh/yr.
The U.S. average residential use is ~ 12,000 kWh/yr. or so, maybe a bit more.

I lived in Buffalo for 25 years before moving to CA in 1995. While in Buffalo I retrofit a 2,000 ft.^2 house. After the retrofit I averaged about 5,000 kWh/yr. electricity and about 27,000 ft.^ of natural gas/yr. use, and in doing so reduced the home's energy use by ~ 2/3 from my starting use by conservation techniques alone and lived quite comfortably.

Folks in other developed countries average much less than I do, albeit with generally smaller dwellings.
I'd suggest using less electricity or energy in general is a somewhat easy goal to achieve using available techniques, common sense and some persistence.

What's your annual use ?