Solar panels for the home...

Something doesn't line up but it just may be how you are describing it. It may be you are getting confused on KW vs KWH. An 8 KW system is 8000 watts of panels, There are no commercially available panels rated for 1 KW each so I expect that he is proposing installing some combination of panels that produces 8 KWH per day. The difference is that a 1Kilowatt ((1KW) set of panels lined up in perfect sun conditions (called STC)are lined exactly perpendicular to the sun for one hour, it produces 1Kilowatt hour(1KWH). The sun moves all day and the panels don't plus it rains on occasion and the length of daylight varies, so the designer of the array uses a program like PVWatts and your location to estimate how many watts of panel you need to generate 8 KWH. 8 KWH per day is actually quite a small system. My 4800 KW of panels put out 28KWH on a recent sunny day, of course The day before it put out about 2 KWH. Thus the first question is what is the rating of each panel?. Current grid tied panels range from 245 to 335 watts per panel. The going rate for a installed solar system is around $3 to $5 per installed watt of panel rating. Then subtract the CT incentive and federal tax credit. I would be quite surprised if the proposed system is anywhere near the size you need to offset your load on a day to day basis but that's what PV watts will tell you as it calculates the output over the course of the year.

A seven year payback is about the going rate for a commercially installed system. The 25 year warranty is a bit of an issue, the industry is still growing and few companies will be around in 25 years. Enphase microinverters is about the only company that offers 25 years and they haven't made a profit since they started, I am not sure how bankable a 25 year warrantee is from them. Same with solar panels, few companies seem to be it in for the long haul. Central inverter warrantees at best are 10 years. The panels themselves unless they have manufacturing defects should last 25 years or more although they will lose some capacity as they age.

Shading of the panels is a major no/no and in order to comply with rebates the installer has to check for shading to the south and that usually means no trees to the SE,S & SW of the panels. Trees grow and you need to make sure that someone doesn't build a large structure or grow large trees to block your sun. Check your roof pitch, if the roof holds snow, you may have issues with snow on the panels in winter.

One general note is that a standard grid tied solar system does not work when the power goes out. One firm SMA offers an emergency power option for larger systems but it has a slightly higher initial cost. You can get a system with battery backup but plan on several thousand dollars more up front plus occasional expensive battery change outs.

I haven't had a power bill for a couple of years and haven't had any significant issues except the power company zapped one of my inverters. It was on warrantee and I got a replacement quickly.I would check your net metering options with your utility, some systems only let you carry a credit for 12 months and then they reset while others like NH allow me to run a ongoing surplus.The fed rebate goes away in 2016 so you have some time but not forever to get a system installed..Check to see if you can get SRECs which is an ongoing incentive that depends on how much power you generate.

Check out my thread. I get a chuckle from those who demand short term payback for an "infrastructure" home improvement. Do you buy a house that will payback in 7 years? And a house is far more an expense than an asset. Based on alternative current, very safe, tax free, inflation hedged investments, IMO my system is an absolute winner. https://www.hearth.com/talk/threads/solar-electric-6-5-kw-system.116031/

The link also discusses shading, and I fully agree that shading can be a serious issue. I regard my shading as as inconsequential.

My environmental manager at my work (trash to energy plant) has the following:

Grid tie solar with nety metering but no battery backup. He has the minimum $17 / mo POCO charge to be grid connected, but other than that he essentially has no electric costs. some months he has a small bill, some moths a small credit. I'm not sure how big his system is, but for he & wifey it does as above. If the 2 kids are home from college / military the electric use is higher.

He has oil / HW baseboard but rarely uses it for heat, but it is hot 24/7 due to the tankless DHW coil. I have pointed him toward electric DHW or HPWH DHW (GeoSpring & Geyser).

He heats with a ducted pellet hot air furnace. There is no A/C.

He did mention something rather strange about his electric rates. There is a certian cut off date associated with peak demand pricing and a subsequent lock in at lower rates. Basically he turns off the hot tub in the summer. This drops his summer peak demands and puts him in a lower $ / KW bracket for the winter months. In winter he can run the tub on the cheap. It allmost sounds a55 backwards.

If the trees are providing a lot of shade for the house in the summer, you will increase your need for a/c in the summer - a lot. In Nov., Dec, Jan. you will get very little power from your panels and there is nothing you can do to change that. Solar can make a great addition to your energy plan but you have to look at everything.

BTW, I've been doing a ton of research on Solar but not posting much. $8K for an 8Kw system installed seems too cheap.

I think there is some easily corrected confusion here. If your demand averages 7 kWh/day throughout the year, and you have a (reasonable) average of 4 hours of sun/day, then a (fairly normal) 250W panel would produce 1 kWh (4hours x 250 Watts = 1000 Wh, or 1 kWh) per day.

Every home is different on usage. Your neighbor could have electric hot water, electric range, electric stove, 3 kids, etc. His usage might be three times yours, thus three times the number of panels.

As far as payback goes, if you are producing 8 kWh/day for 365 days/year, that is 2,920 kWh/year. To pay back a $4900 (net) system in 7 years, your electricity would have to cost 24 cents/kWh (2920 kWh/year * 7 years = 20,440 kWh, $4900/20,440 kWh = 0.239 $/kWh). I don't know what retail electric rates are in CT now or during the summer, but an average of 20 cents (or more) per kWh wouldn't surprise me one bit.

As far as reliability goes, while your solar panels (if they are not cheap Chinese made junk - my opinion) may last 25 year, the inverter most certainly will not. Expect to have to replace this every 10 years or so. Anything beyond that is a bonus.

I'm with jebatty on payback. Do this because you want to invest in power price certainty, or because you think it is the right thing to do. I wouldn't make the call based on whether it was 7, 10, 12, etc. years of payback. It will most certainly be <15 year payback, for what it is worth.

I can tell you right now, you're not going to get 1kWh out of each of those 8 panels every day, especially not in winter. You might get it 5 months of the year, if you're lucky and have 0 shading problems. It would be worth your time to go talk to your neighbor with the panels. See if you can get specs, and real world data.

My experience is with my own 20 panel, 4.4kW(DC) system in the "Sunshine State" at roughly 26.8°N. My sunshine cuts through a lot less atmosphere than it does to reach central NH.

Here's where I go to mine data for my friends when they ask me what solar would do on their home:

Look around the map here:
https://enlighten.enphaseenergy.com/public_systems
After you zoom in, click on one of the little orange E cartoon bubbles. Some of them will bring up systems on the right side of the screen with links that can be followed to review the actual system data.

You may wish to look at these systems for reasonable example sake:
https://enlighten.enphaseenergy.com/pv/public_systems/Dh5Z20778/grid/months
https://enlighten.enphaseenergy.com/pv/public_systems/xRcD16574/grid/months

Given that both of these example systems were installed in 2011, we can make some basic assumptions: these are not current cutting edge systems, a modern panel + inverter might generate ~5-20% more energy per day than these do. (However, these example systems may actually have been SolarWorld 240 mono panels with Enphase M215 inverters which would put out very close to what a modern 250W panel would). Take any system's output data (in kWh), divide it by the number of panels listed for the system (or # micro-inverters listed), and multiply the result by 8 for your proposed system. For broad brush strokes, look at the monthly data. Compare that monthly kWh # you computed to some of your energy bills over the last few years.

From what I see, 8 panels might cut it in the summer months, but not the cold half of the NH year.

One thing to note about incentives: the federal incentive is a "Credit" against your wage based tax liabilities. It is possible that you may have to roll a portion of the credit forward into the following tax year, so waiting to 2016 might not be the best plan for all wage earners. Consult your tax advisor to determine what is best for your situation.

Where2 said:

you're not going to get 1kWh out of each of those 8 panels every day

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I was discussing "average" not guarantee or typical. If you have net metering, average is what counts. Of course, the daylight is shorter in the winter, so there will be less production.

This link http://www.nrel.gov/gis/images/eere_pv/national_photovoltaic_2012-01.jpg indicates average sun hours/day for photovoltaic systems - it shows between 4 to 4.5 for NH or CT. If the panels are 250W, and the sun shines 4 hours a day, that is 1000W, less any inverter and other system efficiencies (realistically, this would mean about a .88 multiplier or so in the Northeast, leaving ~880 Watts.

The OPs original question was "is the installer feeding me a line of bull*&^%?" and I think the answer in terms of system sizing (based on his 7 kWh/day usage) is "no".

Solar is definitely a salesman dream. To the average homeowner its difficult to understand and with the myriads of incentives that vary, its easy to obfuscate the truth.

Just following the numbers to get an idea of costs and if I were to do it I'd want to be able to at least heat (with a heat pump) and cool with it. For me that would take more like 30 or 40 kwh/day (or maybe even more). That's a lot of panels.

Warm_in_NH said:

While solar is probably a good way to go for many, when we need to cut down a combined growth of over 600 years worth of healthy trees, I just can't bring myself to consider it an option at this time.

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Kudos to you - those trees are doing some good just where they are, and will for a long time to come.

This may read to be a little absurd for a guy like me heavy into sustainable forestry management, but I too could not cut down trees around our house to allow a roof mount solar system. The solution was buying some open land from a neighbor and installing a ground mount system about 300 feet from the house with underground wiring, including going under the public road. The cost of the land, of course, is not included in my system cost. System cost before any incentives was around $4.75/watt and around $3.40/watt after the federal tax credit. I am very happy with the ground mount which is very easy to clear of snow. In our area panels could remain snow covered for a 1-2 months, and I would not look forward to climbing up on a snow covered roof to clear panels of snow. Winter production (Nov-Jan) is only about 30-40% of summer production, but every watt counts when you have a solar system.

March predicted daily average for me is 27kwh/day and I am averaging 33 kwh/day. Dec daily average was about 9 kwh vs 13.5 kwh predicted. July average is predicted at 39 kwh/day.

OP, this thread has gotten me a interested in solar. Do you recommend any of the installers that you've talked to? Are you in NH or CT (can't tell from your posts)?

Does anyone have a solar PV installer they can recommend for South Eastern, NH? I see Revision Energy out of Exeter (and Maine).

Revision travels all over NH and into Mass. I would definitely have them on your list. They have done several systems up in North country (Randolph and Milan NH)

They are big enough to buy panels and inverters in bulk. I think they do mostly microinverter installs which means that they have a standard kit that they carry that covers 95% of the install parts. Most of the time they can be in and out in a day.

Biggest obstacles for most folks is shading, roof orientation and the age of their roof (don't install a new solar system on an old roof as it will last far longer than the roof).

peakbagger said:

Biggest obstacles for most folks is shading, roof orientation and the age of their roof (don't install a new solar system on an old roof as it will last far longer than the roof).

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I think I am good on the shading. My roof points southwest. And the roof is only 2 years old (unfortunately its asphalt and not a fancy metal one) and they stripped it down to the sheathing so there is only one layer of shingles. So maybe I'm in business!

I'll follow up with a phone call to Revision.

I got three quotes and ultimately selected ReVision to do my install. I went live Oct 2012. They were genuinely interested in doing a good job. My house is almost 100 years old, but my asphalt roof was only 3 months old. They got it done in 4.5 days (they predicted 3), but the crew leader was a real perfectionist to make sure that all the panels lined up such to make a flat plane on an uneven roof. I also bought a bigger system than I needed with the idea of future growth in mind. Sure enough, I bought a Chevy volt in Oct of 2013. We'll see if I sized it right to break even next fall.

Good luck.

The Volt was fine . . . once the need to obsessively hypermile wears off. Used engine assist for heat a lot because it was either cold or I had the family in it. I can deal with just the heated seat when temps are in the 30s, but below that for anything more than a short trip and I fold. Low life time mpg was 125. Back up to 140 now and expect to peak around 180-200 at some point.

We got a higher amount of snow than usual here in New England. People were starting to sour on the snow in February. Come on . . . its New England. Using L gear makes the car much better in the snow than I had expected, so much so that I hardly used my truck. It really is a well thought out vehicle.

Well I have ReVision coming out but not until a week from Wednesday. I can't wait.

Meanwhile I'm trying to figure out what will fit on the roof. Its a 26' long by 15' pitched roof. I'm bummed because I wanted to go with 5+ kw and it looks like standard 250 panels run at around 65"x40" or so. So I'll only be able to get 16-18 on the roof based on my calculations. It looks like either a grid of 4x4 running the long way. Or a grid of 2x7 with a row of 1x4 at the bottom would work. Oh well 4.5 kw will be okay too if that is all I can fit. But I was really hoping for 3 rows of 8 and 24 panels total for a nice 6 kw array. Doesn't look like that is going to happen.

I've been in that predicament. There's only 4.4kW on my second floor roof, because that was all that would fit...

4.4kW is better than 0kW.

Steve from ReVision assessed my set up. He had a lot of good ideas and was open to reasonable input. At the time they sold Canadian Solar panels (made in China), Suniva (made in USA - what I got) and Sunpower ( Philippines, I think. Supposedly the gold standard, but also very expensive). I got a 6.3 kW system, but realistically it runs a bit less than that.

Sunpower might get you more energy per square ft, but you'll pay more for them.

If you have any shading issues at all, get microinverters instead of a single or two string inverters. With a string, if one panel gets shade, all the others on that string only produce what the shaded panel gets. Plus microinverters allow you to detect if there is an issue with one panel instead of having to guess which on the string it is. This actually happened to me. A squirrel built a nest under a panel and chomped through a wire. Revision came back and installed a rodent proof mesh between panels and roof.

If you get microinverters, ask if and where they clip. My enphase have a max of 225 W. Might have higher rates ones now. Even though my panels are rated for 255W, I can never get that. Realistically, though, they very rarely get to 225. Often I hit between 210-220 when angle of sun is right. Max out in Jan or Feb if we have a 10 F day as the panels become more efficient with colder temps. That's probably why April is my best month. Balance of being somewhat cool and longer days.

Good luck.