Looking to go solar...everything looking good, am I missing something?

[HX_Guy]

Ian, thanks again for the link to your numbers, very helpful.

I took the numbers of your 6.9kW system and applied them to a 10.5kW (assuming it's linear) and got a yearly production of 18,621 which is close to the 18,020 I was quoted today. I then used a 1.52 multiplier and applied it to the past 12 months and compared the production to our usage. Now of course this is a total estimate but I'm hoping it's close to +/-10%.



This is based off the standard rate plan, not the TOU. Figuring the TOU would be a lot more difficult, I may do it if I get super bored.
According to this, I could see a potential savings right off the bat of ~$300/year. After the solar system is paid off, then the savings would be $2,400 per year. Does that seem about right?

[HX_Guy]

Yeah, I would be interested in that spreadsheet. I made one way back before solar but it's a mess and not really well-suited to comparing the standard with TOU rates.

Check your messages, I sent you a link to the Google Docs spreadsheet.

[J.P.M.]

Whoa that's awesome! I love stuff like that (graphcs/tracking/etc), will definitely look at it more in depth in a bit here.

Your yearly usage sounds close to ours, we're a bit higher but not much more at about 20,000 kWh. So even with a somewhat smaller system like that, you're still over producing peak power? Have you calculated what it would mean for your bills if you went with the standard rate? Let me know if you need a spreadsheet with all the APS formulas already inputed, you would just need to plug in your kWh used per month.

FWIW, Further to local system output and some SWAG check as to potential output as an adjunct/check on PVWatts or other tools - check out PVOutlet.org., go to "teams", "United States", then map to your area. It appears Phoenix has 4 systems. I'd only caution to keep in mind individual local results will be different because of different tilt and azimuth as well as shading and other conditions. If you find two systems w/ similar tilt/az. it's interesting to note the usual close agreement in output per D.C. Watt irrespective of panel make.

[josefaz]

Ay! There's definitely a lot of things to consider.

I did see some numbers on another site from someone in Phoenix who was on the noon-7pm TOU and you're completely right, they had a bunch of excess kWh on-peak and no enough off-peak, but with off-peak being 1/4 of the cost of on-peak power, it still worked out better in their opinion. Then someone else chimed in and said they are on the standard rate plan and they found that it worked best for them.

I guess it goes without saying that it will depend from person to person. We are currently on the noon-7pm TOU already and we use quite a bit on-peak since we are home all day and keep the A/C at 77º even during the day, and have a 5 ton and a 1.5 ton A/C system.

Is there really a way to accurately calculate? I mean I know how much we use on-peak vs off-peak, but how do you figure how much the system will produce between the different hours? How big is your system Ian and which way do the panels face? What is your production like if you don't mind sharing?

Another Phoenician here... I signed up with Solar City back in Jun 2012 and had the 11.5 KW system installed in mid Nov 2012. Back then I had options of what type of inverters and panels to install. Check if you have that option as well and research the available panels/inverters they have. I'm with APS and before installation I'm on the TOU as well but changed to standard in the beginning of 2013. If I remember, I think the rule of thumb was if your overall monthly usage is less than 1 Kwh, the standard rate will cost you less vs the TOU.

Just to give you an idea since the system you have in mind is almost the same size. In 2013, my system produced about 19200 KWh and an excess of 3400 Kwh at the end of the year. Solar City's estimate was 16500. Your south facing panels may produce more. Half my 48 panels face east and the other half west.

[HX_Guy]

That's a lot of panels! I don't think we can fit that many...or we could, but I don't want any facing west or north as then we'd see them from the street coming home and I don't want that. Good to hear that the system produces more than they estimates, seems that's the trend with everyone.

[HX_Guy]

Received a second estimate, the guy is actually still here on the roof but he did an estimate before he came out. The system is smaller at 8.64kW but the price per watt is actually cheaper than the bigger system which impressed me. He said if we wanted a bigger system (and he's up on the roof measuring for how big of a system we could have), the price should come down (per watt).

This is what I was quoted...

Hanwha HSL60P6-PA-0-240TB panels and Fronius USA IG+ A 7.5 240 Inverter total system cost of $25,574.80 or $2.85/watt. After tax credits, it would be $16,202.36 or $1.88 per watt. Price seems pretty good, but I have no idea if the panels are any good.

Input?

[HX_Guy]

Received updated quotes from the guy that stopped by earlier today. Very impressed with their thoroughness and professionalism and their prices seem pretty good I think, but hopefully I can get some more input on that. He has been the only to to actually go up on the roof and do measurements plus used some sort of device to calculate if there will be any shade in the winter months because our south neighbor has a 2 story house. Doing that, he actually figured that there would be some shade on the lower part of the roof and laid out the panels in a different configuration.



He gave me two quotes on bigger systems, one using the same Hanwha panels and the other using LG panels. The LG panels have better specs and I have to assume are better reliability wise, just by the brand recognition? He gave me two quotes on bigger systems, one using the same Hanwha panels and the other using LG panels. The LG panels have better specs and I have to assume are better reliability wise, just by the brand recognition? Both panels have a 25 year warranty, though I thinking theres a much higher chance that LG will still be around 25 years from now

Quote #1: 10.06kW system producing 16,564 kWh per year
42 x Hanwha HXL60P6-PA-0-240TB 240W panels
1 x Fronius USA IG+ A 10.0-240 inverter
$28,576 pre-tax credits ($2.85/watt) - $19,003 after tax credits ($1.90/watt)

Quote #2: 10.92kW system producing 18,121 kWh per year
42 x LG LG260S1C-G3 260W panels
1 x Fronius USA IG+ A 10.0-240 inverter
$32,552.85 pre-tax credits ($2.98/watt) - $21,787.00 after tax credits ($2.00/watt)

Feedback on either of those? Thanks.

[Ian S]

Quote #1: 10.06kW system producing 16,564 kWh per year
42 x Hanwha HXL60P6-PA-0-240TB 240W panels
1 x Fronius USA IG+ A 10.0-240 inverter
$28,576 pre-tax credits ($2.85/watt) - $19,003 after tax credits ($1.90/watt)

Quote #2: 10.92kW system producing 18,121 kWh per year
42 x LG LG260S1C-G3 260W panels
1 x Fronius USA IG+ A 10.0-240 inverter
$32,552.85 pre-tax credits ($2.98/watt) - $21,787.00 after tax credits ($2.00/watt)

Feedback on either of those? Thanks.

For some reason, the annual production for the LG system is somewhat higher than expected compared to that expected from the Hanwha system. The nameplate power of the Hanwha system is 42 X 240 = 10.08 kW; that for the LG system is 42 X 260 = 10.92 kW.
(10.92/10.08) X 16564 = 17944 which is 177 kWh less than the 18121 given. Since it was the same guy doing the estimating, I wonder why that is. Maybe the LG panels have less deterioration or just better performance wrt nameplate? Dunno.

[JohnInSoCal]

holy cow why is solar so cheap in AZ ? $2.85 a watt ? But in CA I can only get around $4 a watt (not using discontinued panels or anything like that)

[HX_Guy]

Ok so here come the big dogs! I finally got a quote on SunPower panels and inverter, which everyone seems to agree are the best in the industry. They actually quoted me on the largest system yet, 11.2kW, to cover 100% of yearly electricity. I'm waiting to receive the month-by-month production number so I can plug them in and see if it's worth going with a system that big.

11.2kW system producing 21,300 kWh per year
35 x SunPower SPR-320NW-WHT-D 320W panels
1 x SunPower SPR-11401f-i UNI inverter
$43,904 pre-tax credits ($3.92/watt) - $29,732.80 after tax credits ($2.65/watt)

You do get a better "bang for your buck" on these more expensive systems because you get a lot more back tax credit wise. So for example a $44,000 system will end up being $30,000 net, while a $31,000 system would be $21,000 net...so you get $14,000 for $9,000 basically.

One thing I've learned, which I wasn't told of until today, is that these 2.99% financing deals seem to only be available on the higher priced panels (SunPower, SunEdison). The lower priced (Canadian Solar, Hanwha) have a rate of 7.99% so you're getting a lot less for your money, combined with less tax credit, doesn't really seem to make a lot of sense.

[JCP]

Ok so here come the big dogs! I finally got a quote on SunPower panels and inverter, which everyone seems to agree are the best in the industry. They actually quoted me on the largest system yet, 11.2kW, to cover 100% of yearly electricity. I'm waiting to receive the month-by-month production number so I can plug them in and see if it's worth going with a system that big.

11.2kW system producing 21,300 kWh per year
35 x SunPower SPR-320NW-WHT-D 320W panels
1 x SunPower SPR-11401f-i UNI inverter
$43,904 pre-tax credits ($3.92/watt) - $29,732.80 after tax credits ($2.65/watt)

You do get a better "bang for your buck" on these more expensive systems because you get a lot more back tax credit wise. So for example a $44,000 system will end up being $30,000 net, while a $31,000 system would be $21,000 net...so you get $14,000 for $9,000 basically.

One thing I've learned, which I wasn't told of until today, is that these 2.99% financing deals seem to only be available on the higher priced panels (SunPower, SunEdison). The lower priced (Canadian Solar, Hanwha) have a rate of 7.99% so you're getting a lot less for your money, combined with less tax credit, doesn't really seem to make a lot of sense.

If I may ask, what do you do to use so much electricity? I get the summer months with the AC on 24/7, but over 1000 KWh/month during the winter seems high to me.

[Ian S]

If I may ask, what do you do to use so much electricity? I get the summer months with the AC on 24/7, but over 1000 KWh/month during the winter seems high to me.

Well, it could be the use of a heat pump - we do see sub freezing temperatures here in Phoenix. But then I look at my August usage prior to solar for a 2300 sq.ft house and see 3500 kWh consumed. And I don't have a swimming pool. My annual is 18750 kWh so his home wouldn't have to be much bigger to reach those numbers.

[Ian S]

holy cow why is solar so cheap in AZ ? $2.85 a watt ? But in CA I can only get around $4 a watt (not using discontinued panels or anything like that)

Because no reasonably sane person wants to live in this heckhole!

[HX_Guy]

Our heat is actually on gas. The crazy thing is that even the in winter, our A/C runs. We set it at 77º and if it turns on, it turns on...and sometimes it does. Our house is 2,900 sq ft and now we added a pool too so the usage is going to be even bigger. It's a variable speed pump though so that is supposed to help.

[J.P.M.]

Our heat is actually on gas. The crazy thing is that even the in winter, our A/C runs. We set it at 77º and if it turns on, it turns on...and sometimes it does. Our house is 2,900 sq ft and now we added a pool too so the usage is going to be even bigger. It's a variable speed pump though so that is supposed to help.

I'd suggest either increase the A/C temp. or turn the heat thermostat down, or get something checked out. Sounds possible that the house is overheating perhaps due to solar gain and/or a warm winter day, and not much or poor use of thermal mass to prevent overheating. Does A/C come on mid-late afternoon ? If so, that may be the cause.