11kW system in SoCal - need advice please?

[dusterbuster]

Update: I've added a forth option listed as Option D below. I'm narrowed my decision between Options A and D, and would love to hear any thoughts/opinions people have regarding: (1) comparison of the two SMA SB5000TL-US inverter setup versus the SolarEdge 9000 + SolarEdge P320 Optimizers setup, and (2) the LG 305 panel versus Solar World 285 panels. Thank you!

Option D: ($3.37/watt)
Solar World 285 panels (39 panels) = 11.115 kw
(x2) SMA SB5000TL-US inverters (10 year warranty)
20 year workmanship warranty
1st year production estimate: 16,739 kWh
$37,500 base price (before federal tax credit)

_______________________

Hi everyone,

I'm planning to install a 10.5-11kW system at our house in Santa Monica. We have a single story Santa Fe style home, with a flat roof, so there is plenty of space for panels. We don't currently have any shade issues. I say currently because there is a single story house to the South, which I can imagine at some point getting torn down and replaced by a 2 story home. There is a relatively tall 2-story home to the North, but I don't think it would interfere until very late in the day.

Here are 3 options/bids I'm currently considering:

Option A: ($3.45/watt)
LG 305 panels (36 panels) = 10.98kW
SolarEdge 9000 inverter (12 year warranty)
SolarEdge P320 optimizer
10 year workmanship warranty
1st year production estimate: 16,347 kWh
$37,861 base price (before federal tax credit)

Option B: ($3.15/watt)
REC 315 (35 panels) = 11.025kW
SolarEdge 9000 inverter (12 year warranty)
SolarEdge P320 optimizer
10 year workmanship warranty
1st year production estimate: 16,414 kWh
$34,728 base price (before federal tax credit)

Option C: ($3.45/watt)
SolarWorld 315 Mono Pro (33 panels) = 10.395kW
SMA SB 9000TL-US inverter (10 year warranty)
10 year workmanship warranty
1st year production estimate: 15,161 kWh
$35,863 base price (before federal tax credit)
[Option C bid was obtained using lower electricity consumption projection (before accounting for a second electric car), so probably we probably would increase the capacity to match the other 2 options]

[J.P.M.]

With a flat roof, what panel tilt do you envision using, keeping in mind that horizontal panel orientation impairs production and needs more cleaning ?

[jflorey2]

I would love to hear any thoughts/recommendations people have regarding the above 3 bids (ranking, etc.).

The SMA TL-US inverter will allow you to power critical loads during the day when the power goes out, which is a nice feature. Not much of a big deal in Santa Monica though.

I'm also considering trying to get an additional bid that would include microinverters, primarily for the longer warranty on the irverter (since we don't currently have shade issues). At some point, we may consider adding battery storage as well.

Microinverters and battery storage do not generally play well together. You would be unable to use the solar with the battery system without the use of AC coupling, which is a somewhat painful and difficult arrangement to set up. In general, if the system is not designed from the outset to be battery-compatible you'll end up with two completely separate systems - your grid tied PV system and a battery backed system - with no reasonably priced way to connect the two if needed.

What are you considering using the battery system for? If it's just occasional short outages then there's no real need to connect it to solar anyway.

[dusterbuster]

With a flat roof, what panel tilt do you envision using, keeping in mind that horizontal panel orientation impairs production and needs more cleaning ?

That's a good question. I've only received bids through a solar bid service/site (recommended by the city of Santa Monica), so I haven't actually spoken directly with any of the installers. Once a bid is accepted, the installer needs to come out to survey the house and propose a specific plan that I would need to approve. I guess at that point I would be able to discuss the recommended tilt for the installation.

[dusterbuster]

The SMA TL-US inverter will allow you to power critical loads during the day when the power goes out, which is a nice feature. Not much of a big deal in Santa Monica though.

Microinverters and battery storage do not generally play well together. You would be unable to use the solar with the battery system without the use of AC coupling, which is a somewhat painful and difficult arrangement to set up. In general, if the system is not designed from the outset to be battery-compatible you'll end up with two completely separate systems - your grid tied PV system and a battery backed system - with no reasonably priced way to connect the two if needed.

What are you considering using the battery system for? If it's just occasional short outages then there's no real need to connect it to solar anyway.

I didn't realize the SMA TL-US inverter had that ability. That would be something nice to have, although you're right that it's probably not too big of a deal for my situation (can't recall when the power last went out for an extended period). The solar bidding service rep did say that the SolarEdge inverter with the optimizer would be considered a better inverter than the SMA TL-US. Does that sound right?

Also, good point about the potential issues with trying to add battery storage later. It's probably not really beneficial in my case, so probably something I won't end up doing realistically.

[solar_newbie]

I would like to use micro inverter since it is the way to go. I just learn that SunPower is released solar panel with micro inverter included as it bought a company to do it.
It is the future.

[paul65k]

That's a good question. I've only received bids through a solar bid service/site (recommended by the city of Santa Monica), so I haven't actually spoken directly with any of the installers. Once a bid is accepted, the installer needs to come out to survey the house and propose a specific plan that I would need to approve. I guess at that point I would be able to discuss the recommended tilt for the installation.

That sounds like the way they would do things in the Peoples Republic of Santa Monica.....Just sayin'

In all seriousness You have a long way to go in making a 20+ year decision. It is easy to throw $$ at a solar install and this can happen without the right homework just remember anyone trying to sell you something is going to have their and not your best interests at heart so you need to get educated, this is a great start and I would also suggest that you Google and download Solar for Dummies and read it thoroughly, then start talking to potential suppliers.

I would also question the need for that much solar capacity, I get that SM does have some morning overcast issues but even still what is driving such high capacity in your case??

Good luck and start reading

[J.P.M.]

That's a good question. I've only received bids through a solar bid service/site (recommended by the city of Santa Monica), so I haven't actually spoken directly with any of the installers. Once a bid is accepted, the installer needs to come out to survey the house and propose a specific plan that I would need to approve. I guess at that point I would be able to discuss the recommended tilt for the installation.

It's an even better question if you hope to get some idea of annual production. If you have sizes and bids, that strongly implies (to me at least) the orientation and means to achieve that orientation have been proposed. If it's a horizontal orientation, there are considerations you may be unaware of like more frequent cleaning and access for maintenance.

No offence intended, but it may be that your solar ignorance will create problems down the road. NOMB, concern or $$, but it looks to me like you're considering spending a large sum of money on something you seem to know little about.

[dusterbuster]

It's an even better question if you hope to get some idea of annual production. If you have sizes and bids, that strongly implies (to me at least) the orientation and means to achieve that orientation have been proposed. If it's a horizontal orientation, there are considerations you may be unaware of like more frequent cleaning and access for maintenance.

No offence intended, but it may be that your solar ignorance will create problems down the road. NOMB, concern or $$, but it looks to me like you're considering spending a large sum of money on something you seem to know little about.

Thanks for the advice, and no offense taken. I've already downloaded and flipped through much of the Dummies book, have been consulting with friends who installed solar, and then working through the city-recommended consultant/bid collector. Still, I certainly acknowledge my ignorance in this area, so I'm trying to catch up as much as possible, and appreciate the insight/advice from forum members here.

I've also updated the original post to list the first year production estimates. I'm trying to get more information behind how these production estimates were calculated.

[SolarFamilyGuy]

Hi everyone,

I'm planning to install a 10.5-11kW system at our house in Santa Monica. We have a single story Santa Fe style home, with a flat roof, so there is plenty of space for panels. We don't currently have any shade issues. I say currently because there is a single story house to the South, which I can imagine at some point getting torn down and replaced by a 2 story home. There is a relatively tall 2-story home to the North, but I don't think it would interfere until very late in the day.

Here are 3 options/bids I'm currently considering:

Option A: ($3.45/watt)
LG 305 panels (36 panels) = 10.98kW
SolarEdge 9000 inverter (12 year warranty)
SolarEdge P320 optimizer
10 year workmanship warranty
1st year production estimate: 16,347 kWh
$37,861 base price (before federal tax credit)

Option B: ($3.15/watt)
REC 315 (35 panels) = 11.025kW
SolarEdge 9000 inverter (12 year warranty)
SolarEdge P320 optimizer
10 year workmanship warranty
1st year production estimate: 16,414 kWh
$34,728 base price (before federal tax credit)

Option C: ($3.45/watt)
SolarWorld 315 Mono Pro (33 panels) = 10.395kW
SMA SB 9000TL-US inverter (10 year warranty)
10 year workmanship warranty
1st year production estimate: 15,161 kWh
$35,863 base price (before federal tax credit)
[Option C bid was obtained using lower electricity consumption projection (before accounting for a second electric car), so probably we probably would increase the capacity to match the other 2 options]

I would love to hear any thoughts/recommendations people have regarding the above 3 bids (ranking, etc.). I'm also considering trying to get an additional bid that would include microinverters, primarily for the longer warranty on the irverter (since we don't currently have shade issues). At some point, we may consider adding battery storage as well. I initially was told that the SolarEdge 9000 inverter could be retrofitted to accept SolarEdge's StorEdge Tesla Powerall system, but then was informed today that only the SolarEdge 7600 model has the capability of being upgraded for use with the upcoming StorEdge/Tesla Powerwall system (which seems inconsistent with statements I've previously read from the company).

Sorry for the long post!

Remember, every time one of those micro inverters goes bad, your installer has to climb onto your roof, remove all the panels, replace the bad unit, and re-install the panels. Every time somebody climbs onto your roof, you shorten the life of your roof. Keep this in mind. IMO, micro inverters are only good for ground mounted solar arrays. On top of a roof of a residential home, not so much. Again, (in my opinion).

[J.P.M.]

Thanks for the advice, and no offense taken. I've already downloaded and flipped through much of the Dummies book, have been consulting with friends who installed solar, and then working through the city-recommended consultant/bid collector. Still, I certainly acknowledge my ignorance in this area, so I'm trying to catch up as much as possible, and appreciate the insight/advice from forum members here.

I've also updated the original post to list the first year production estimates. I'm trying to get more information behind how these production estimates were calculated.

Be deliberate and holler back as your needs dictate. FWIW, I bet the self education will pay big dividends. Solar is not rocket science as you may already be finding out.

[jflorey2]

I would like to use micro inverter since it is the way to go. I just learn that SunPower is released solar panel with micro inverter included as it bought a company to do it. It is the future.

I hope not! I want to be able to replace inverters easily (since they generally have the lowest MTBF of anything in the system) and mount them someplace relatively cool to maximize life. I'd also like to keep wire gauge down (for cost vs. efficiency reasons) and a 500 volt system DC needs a much thinner/cheaper gauge than a 240VAC microinverter system.

[paul65k]

I hope not! I want to be able to replace inverters easily (since they generally have the lowest MTBF of anything in the system) and mount them someplace relatively cool to maximize life. I'd also like to keep wire gauge down (for cost vs. efficiency reasons) and a 500 volt system DC needs a much thinner/cheaper gauge than a 240VAC microinverter system.

Fair point but in the OP's case anyplace cool would be his geographic location, namely Santa Monica ..........the median temp there is around 80 which is cooler than many garages in other parts of the country

I keep going back to why such a large system??

[jflorey2]

Fair point but in the OP's case anyplace cool would be his geographic location, namely Santa Monica ..........the median temp there is around 80 which is cooler than many garages in other parts of the country . . .

Which, in turn, is a lot cooler than the back of a PV panel in full sun.

I have nothing against microinverters - they have their place, and for partial shading conditions, work better than non-optimized string inverters. But they also have pretty significant drawbacks. I'm glad we have both options.

[dusterbuster]

Fair point but in the OP's case anyplace cool would be his geographic location, namely Santa Monica ..........the median temp there is around 80 which is cooler than many garages in other parts of the country

I keep going back to why such a large system??

The size of the system is based on our electricity usage for the past 12 months (15765 kW - which includes daily charging of my wife's electric car for about 2/3 of that period), with additional projected usage based on the recent addition of a second electric car (to replace my ICE car), for roughly around 16500 total projected annual electricity usage.

I'm still a little fuzzy on how the estimated first year production is calculated, as I see different calculators/maps that produce materially different results. I'm trying to get further info on how the estimates for my bids were calculated. However, based on the PVWATTS online calculator (recommended in the Dummies guide), the system size in the above bids seem about right for our projected electricity usage.