4KW in Walnut Creek - Please advise

[kumasdaddy]

So I am down to two installers. Each will do the maximum 15 panels

Installer 1
Solarworld Sunmodule Plus SW 275
Solar Edge Power Optimizer
Only has done 200 installs with very little reviews
December Installation

Installer 2
Mitsubishi PV-MLE265HD
Enphase Microinterveter
Very strong reputation
January Install

Both are at $3.80/W The panels will be spread over 3 different sections of roof. I really am at a loss on which one to go with. Any thoughts or recommendations? would like to finalize this weekend.

Thanks for your advice.

[Bikerscum]

Do you want to wait a year to get the tax credit with installer #2?

[fun2drive]

Do you have a preference regarding micro inverters compared to a string inverter?
I am planning a 10KW min array and to me the installer is very important if you as the owner have decided which way you wish to convert power.
Some installers are like craftsman and well worth the premium they may charge while others are tradesman who do an adequate job. Remember you are going to live with this system for a long time (I assume).

I would go visit a least two installs each have done if that is feasible and that would give you a good indication of what your install would look like.

Please post your decision and most importantly the why behind the decision.
Good luck...

[kumasdaddy]

Do you want to wait a year to get the tax credit with installer #2?

I am not thrilled, but it would not be the end of the world.

[PhoebeAnn]

I went with microinverters

...just fired up my 10kW system (Solarworld 250s, Enphase microinverters) a couple of weeks ago. I have a suboptimal roof, with a few trees in the neighborhood I can't do anything about, so I like the microinverter's ability to ignore small transient shading without dropping the entire string. So far I'm happy with the results. Professionally installed by a large firm who seemed to know what they were doing, and since it was turned on, the utility owes me money. Worked out to about $3.70 per gross watt; time will tell what the cost per usable watt will be.

The big disadvantage of the microinverters is that I'm going to be mighty embarrassed after a hurricane if the grid is down and my fancy PV stuff is down as well. Another proposal suggested a system with a couple of plugs (120 VAC only) that could always be used, but I decided that the most long-term benefit came from the microinverters' efficiency. I do have a backup generator as well, though, so I won't be completely without power, but propane is a lot more expensive than sunshine.

As I watch the results on Enphase's reporting system (which rates a B imho), it's obvious that the panels are not optimally placed. I suspected that when I saw the intial proposed layout, and they did move 5 panels to humor me. I now have 3 self-defined groups (defined by orientation). The 5 panels they moved for me ("Group 1") are producing about 25-27% more power than those remaining in Groups 2 and 3. By moving one panel in Group 2 and tilting 7 others in Groups 2 and 3, I'm pretty sure I will gain the equivalent of 2 additional panels, but the original installer isn't interested. So if I were to do it again, I'd make sure the installer was a bit more creative. I'm looking now for an installer who can help me as I experiment -- I know the theory pretty well, but know squat about the practice.

[sensij]

You might want to double-check your modules again. Kyocera doesn't seem to make a 275 W panel, or have one in their discontinued products list. The 200-60 series you mention is either 250 W or 255 W.

The Sunmodule Plus SW275 is a Solarworld panel, not Sunpower. I know, they all sound the same.

Are you sure they are both $3.80 / W? That would mean the system cost for installer 1 should be less than for installer 2, since it looks like installer 1 is putting up fewer watts. If the install is occurring on three different sections of roof, which directions are those sections facing?

[kumasdaddy]

You might want to double-check your modules again. Kyocera doesn't seem to make a 275 W panel, or have one in their discontinued products list. The 200-60 series you mention is either 250 W or 255 W.

The Sunmodule Plus SW275 is a Solarworld panel, not Sunpower. I know, they all sound the same.

Are you sure they are both $3.80 / W? That would mean the system cost for installer 1 should be less than for installer 2, since it looks like installer 1 is putting up fewer watts. If the install is occurring on three different sections of roof, which directions are those sections facing?

You are absolutely correct sensij. This process has been so arduous with not being able to compare apples to apples with each installer. Plus not a single installer understood my rate plans. That is why this forum has been so helpful. The two panels are a Mitsubishi and the Solarworld. Installer 1 uses the Mitsubishi's and they come out to 3.975 KW and the Solarworld is 4.125 KW. The average is $3.80 / W for each one as installer 1 matched the $/W of the second. .

As for the directions the panels will be facing, 6 panels will be 202° azimuth, 6 more at 246° and the last 3 at 143°.

[sensij]

You are absolutely correct sensij. This process has been so arduous with not being able to compare apples to apples with each installer. Plus not a single installer understood my rate plans. That is why this forum has been so helpful. The two panels are a Mitsubishi and the Solarworld. Installer 1 uses the Mitsubishi's and they come out to 3.975 KW and the Solarworld is 4.125 KW. The average is $3.80 / W for each one as installer 1 matched the $/W of the second. .

As for the directions the panels will be facing, 6 panels will be 202° azimuth, 6 more at 246° and the last 3 at 143°.

Yeah, your rate plan is a #$%^ to model. You mentioned PG&E, are you using EV-A? It looks like the plan effective Oct. 1 already has the shift in peak hours that I was worried about in the other thread.

If that is the correct rate plan, I attempted to model it for the system you are proposing, using NREL's SAM for generation data and spreadsheets to turn the hourly kWh output into dollar values. I am just a random guy on the internet, and playing with this for free, so please consider that you may be getting what you pay for.

Here is what I came up with:

Solarworld 275's
Generation (kWh)
Total = 6371
Summer off-peak = 1065
Summer partial-peak = 2011
Summer peak = 1142
Winter off-peak = 568
Winter partial-peak = 1113
Winter peak = 472
Credit Value
$1373.65 / 6371 kWh = $0.216 / kWh

Mitsubishi 265's
Generation (kWh)
Total = 6196
Summer off-peak = 1034
Summer partial-peak = 1954
Summer peak = 1111
Winter off-peak = 552
Winter partial-peak = 1083
Winter peak = 460
Credit Value
$1336.13 / 6196 kWh = $0.216 / kWh

This assumes that you get full retail credit for the time of day in which the energy is generated. Someone more familiar with PG&E's net metering policies may be able to correct that assumption if it is wrong.

Between the two systems, I'd say that if your payback calculations show that $0.216 / kWh in year 0 clears your hurdle, then go with the bigger of the two systems (the 275 W modules). It seems to me that 200 installs is enough to be good at it.

A more complete financial model would project the PV generation out over a defined number of years, with whatever Poco rate assumptions you think are reasonable. I think there is enough information here for you to attempt those projections if you are interested, but this was just an attempt to look at the two systems and estimate what you might get out of it.

[silversaver]

EV-A at your area charges peak from 2 to 9? and 3 to 7 on holidays and weekend?.... lol That take off the advantage of solar owners.... Gladly SCE weren't the same..... 10 to 6 peak is actually good for solar owners.

I'm in the 11th month of solar and just received a letter from SCE asking me if I want the $$$ or credit to next year which is a nice option

[sensij]

EV-A at your area charges peak from 2 to 9? and 3 to 7 on holidays and weekend?.... lol That take off the advantage of solar owners.... Gladly SCE weren't the same..... 10 to 6 peak is actually good for solar owners.

I'm in the 11th month of solar and just received a letter from SCE asking me if I want the $$$ or credit to next year which is a nice option

I hope you aren't counting on getting 10 to 6 peak for much longer. Shifting the peak period is one topic that is being seriously discussed in CA rate reform.

I should have mentioned one other thing the analysis above reveals. If you break down the credit value by panel group, you get the following (for the SW 275's):

246 deg: $556 / 2464 kWh = $0.2256 / kWh
202 deg: $563 / 2623 kWh = $0.2146 / kWh
143 deg: $255 / 1285 kWh = $0.1985 / kWh

The marginal value of those SE panels is less than the others and will take longer to recover their cost, but may still be worthwhile to install depending on your other assumptions.

[J.P.M.]

EV-A at your area charges peak from 2 to 9? and 3 to 7 on holidays and weekend?.... lol That take off the advantage of solar owners.... Gladly SCE weren't the same..... 10 to 6 peak is actually good for solar owners.

I'm in the 11th month of solar and just received a letter from SCE asking me if I want the $$$ or credit to next year which is a nice option

The POCO is mandated by the PUC to offer the option of a credit or payment for excess generation. I don't think they are required to tell you about it (the option), so in the informational sense, they did more than probably required of them.

Add: The T.O.U. time schedule differences, one CA POCO to the next, are examples and a result of how everyone is jockeying around now and probably more so in the next ~ 24 months or so as mandated rate reform scenarios play out. All this will make electrical cost projections even more uncertain than they otherwise would be.

[kumasdaddy]

Yeah, your rate plan is a #$%^ to model. You mentioned PG&E, are you using EV-A? It looks like the plan effective Oct. 1 already has the shift in peak hours that I was worried about in the other thread.

If that is the correct rate plan, I attempted to model it for the system you are proposing, using NREL's SAM for generation data and spreadsheets to turn the hourly kWh output into dollar values. I am just a random guy on the internet, and playing with this for free, so please consider that you may be getting what you pay for.

Here is what I came up with:

Solarworld 275's
Generation (kWh)
Total = 6371
Summer off-peak = 1065
Summer partial-peak = 2011
Summer peak = 1142
Winter off-peak = 568
Winter partial-peak = 1113
Winter peak = 472
Credit Value
$1373.65 / 6371 kWh = $0.216 / kWh

Mitsubishi 265's
Generation (kWh)
Total = 6196
Summer off-peak = 1034
Summer partial-peak = 1954
Summer peak = 1111
Winter off-peak = 552
Winter partial-peak = 1083
Winter peak = 460
Credit Value
$1336.13 / 6196 kWh = $0.216 / kWh

This assumes that you get full retail credit for the time of day in which the energy is generated. Someone more familiar with PG&E's net metering policies may be able to correct that assumption if it is wrong.

Between the two systems, I'd say that if your payback calculations show that $0.216 / kWh in year 0 clears your hurdle, then go with the bigger of the two systems (the 275 W modules). It seems to me that 200 installs is enough to be good at it.

A more complete financial model would project the PV generation out over a defined number of years, with whatever Poco rate assumptions you think are reasonable. I think there is enough information here for you to attempt those projections if you are interested, but this was just an attempt to look at the two systems and estimate what you might get out of it.

Thanks my numbers were within $10 of yours.

[silversaver]

I hope you aren't counting on getting 10 to 6 peak for much longer. Shifting the peak period is one topic that is being seriously discussed in CA rate reform.

I should have mentioned one other thing the analysis above reveals. If you break down the credit value by panel group, you get the following (for the SW 275's):

246 deg: $556 / 2464 kWh = $0.2256 / kWh
202 deg: $563 / 2623 kWh = $0.2146 / kWh
143 deg: $255 / 1285 kWh = $0.1985 / kWh

The marginal value of those SE panels is less than the others and will take longer to recover their cost, but may still be worthwhile to install depending on your other assumptions.

I'm not worry of any plan and my solar arrays were facing SW 245deg. I'm still under basic 4 tiers plan. I setup my solar about 120% to accomendating EV. I put up solar to enjoy life while saving the money, not budget hunting....

[silversaver]

The POCO is mandated by the PUC to offer the option of a credit or payment for excess generation. I don't think they are required to tell you about it (the option), so in the informational sense, they did more than probably required of them.

Add: The T.O.U. time schedule differences, one CA POCO to the next, are examples and a result of how everyone is jockeying around now and probably more so in the next ~ 24 months or so as mandated rate reform scenarios play out. All this will make electrical cost projections even more uncertain than they otherwise would be.

I'm still go "bigger" type

[J.P.M.]

I'm still go "bigger" type

Amen. It's a free country and we all enjoy it. I only suggest trying to know the possible and/or likely consequences of decisions made.