Seeking opinions on a Sunpower vs. Kyocera system quote in New Mexico...

[renormalize]

I'm a neophyte regarding solar power so I'd welcome feedback on a PV system proposal I've received. This is intended for a 2700 sq. ft. single-story home under construction in Las Cruces, NM. Panels will be installed at a low angle on a flat roof behind parapets to meet HOA visibility requirements. Contractor features Sunpower but is also willing to install Kyocera panels.

Sunpower System
System Size: 6.213 kW
Year 1 Estimated Production: 11,443 kWh
Panel Type: Sunpower SPR-E20-327 (WHT)
Number of Panels: 19
Inverter: (1) Sunpower SPR-7002m (AFCI, 2MPPTw/SPS) 7000 W Inverter
Mounting Type: Roof mount, ballasted
Total Investment (Excludes Roofing Costs): $24,081
System Cost per Watt: $3.88

Kyocera System (panel model unspecified)
System Size: 6.760 kW
Year 1 Estimated Production: 11,256 kWh
Number of Panels: 26
Total Investment: $23,240
System Cost per Watt: $3.44

(I'm surprised that the two proposed system investments are so similar. And it's unclear to me why the Kyocera system uses 26 260 W panels vs. the 19 Sunpower 327 W panels. Doesn't Kyocera make 325 W panels?)

I welcome your feedback.

[ButchDeal]

(I'm surprised that the two proposed system investments are so similar. And it's unclear to me why the Kyocera system uses 26 260 W panels vs. the 19 Sunpower 327 W panels. Doesn't Kyocera make 325 W panels?)

Kyocera 325w modules are 80 cell (large format). The number of modules doesn't matter much. it is the total size so in your case 6.2kw vs 6.8kw
They have prdicted similar output likely due to more shadows on the larger layout of the Kyocera systems but in the end a pretty similar output.
Did you get any quotes from any other installers?

[organic farmer]

You estimates are just a bit more than what our system cost us [4400 watts off-grid with batteries for $20k], since you would be paying for the net-metering connection I think it sounds about right.

[Yaryman]

Total Investment (Excludes Roofing Costs): $24,081

"excluding roofing costs" - What does that mean?

[J.P.M.]

"excluding roofing costs" - What does that mean?

Probably some roof maint./repair/upgrade/? that was overdue or deemed necessary, and separate from the system cost ?

[J.P.M.]

Decent price on the S.P. ,but still a bit high compared to the Kyocera. BTW, Las Cruces being about the dustiest place on the planet and more prone to mud rain than most any place I've ever been, I'd design the array/location such that you can clean them often. Additionally, the more horizontal the array, the more often they'll' need cleaning. You'll appreciate easy access for all the cleaning the array will need.

[Yaryman]

excluding roofing costs" - What does that mean?

Probably some roof maint./repair/upgrade/? that was overdue or deemed necessary, and separate from the system cost ?

Why don't we wait and hear from the OP before we make assumptions?

I believe there is a some famous saying about assumptions.

You might be right, or maybe it's some way the installer has found to tack on normal costs.

[DanKegel]

$3.44 would be high around here.

What's your expected payback time?

Sunpower is great if you have a small roof, as its panels are more efficient.
260W panels are inexpensive commodity units, and may be a better choice if cost is important.
What inverter would he use with the 260W panels?
Do you have any shading issues?

[renormalize]

Thanks to everyone for their informative comments and questions. Please keep them coming!

With regard to the "Excludes Roofing Costs" proviso, I assume that the installer is just limiting his liability for unexpected costs. Note that this system is going on a brand new custom home that is currently under construction; the builder is experienced with making roofs ready for solar installation, including supporting the additional weight of a ballast-mount system. I'm pretty confident there will be no unexpected additional costs for the roof.

But to be sure, I intend to meet with the solar contractor on Thursday and get some clarification on this exclusion, as well as to ask for more details on the Kyocera system (like payback time and inverter choice). Moreover, I'd like to understand its seemingly inflated cost since my reading suggests that a commodity system should run closer to $3 per watt than $3.50.

Any other suggested questions for me to bring to this meeting?

[J.P.M.]

I'm a neophyte regarding solar power so I'd welcome feedback on a PV system proposal I've received. This is intended for a 2700 sq. ft. single-story home under construction in Las Cruces, NM. Panels will be installed at a low angle on a flat roof behind parapets to meet HOA visibility requirements. Contractor features Sunpower but is also willing to install Kyocera panels.

Sunpower System
System Size: 6.213 kW
Year 1 Estimated Production: 11,443 kWh
Panel Type: Sunpower SPR-E20-327 (WHT)
Number of Panels: 19
Inverter: (1) Sunpower SPR-7002m (AFCI, 2MPPTw/SPS) 7000 W Inverter
Mounting Type: Roof mount, ballasted
Total Investment (Excludes Roofing Costs): $24,081
System Cost per Watt: $3.88

Kyocera System (panel model unspecified)
System Size: 6.760 kW
Year 1 Estimated Production: 11,256 kWh
Number of Panels: 26
Total Investment: $23,240
System Cost per Watt: $3.44

(I'm surprised that the two proposed system investments are so similar. And it's unclear to me why the Kyocera system uses 26 260 W panels vs. the 19 Sunpower 327 W panels. Doesn't Kyocera make 325 W panels?)

I welcome your feedback.

If the orientations are similar, I'd suspect the S.P. system is a smaller electrical size because the Kyocera panels require more area, and so have more shading from the parapets.

I'd suspect the difference in annual output in terms of kWh/yr. per installed kW between the two systems is mostly due to less shading by the physically smaller S.P. system.

Normally, S.P. systems extract about a 15-25 % up front premium over other panels. In your case that penalty looks to be about 10% or so.

For the same location, orientation and the same shading, all equal electrical size systems produce about equal annual output. S.P's advantage(if there is one) is that they have a greater AREA efficiency than other panels by about + 20% or so, meaning that a, say, 5 kW S.P. system will take up about 20% less roof space than another 5kW system using most other panels for the apprx. same annual output for same location orientation and shading.. In your case, the smaller S.P. footprint may mean the S.P. panels can be located so as to be shaded less by the parapets, and the Kyocera system will have a larger shading penalty because it requires more space, some of which may be partially shaded by the parapets.

This may be one of the few cases where the S.P. penalty may be a cost effective choice, or perhaps a less cost ineffective choice than usual.

On the added construction cost: The ballasted system on a flat roof will probably add to the construction costs for beefing up the flat roof.

Any added design and construction costs from adding/changing roof construction costs for going to a ballasted system may be were some of the "unexpected costs" could come in.

On the other hand, penetrations on flat roofs can be more of a problem over time than on a pitched roof.

Know, that ballast load concentrations usually become low spots on a roof after a while and tend to hold or have standing H2O.

When I lived in Albuquerque, I owned a house w/ 9 different flat roof sections/elevations, all flat and all w/ parapets. Nothing to do w/ solar per se, but if you don't know already, I'd respectfully suggest, among other things, pay attention to the parapet details particularly sealing.

[renormalize]

OK, I talked again with the installer and received the following clarifications about their proposal:

--”Excludes roofing costs”: additional garage roofing costs are unlikely because this is new construction with a roof already designed to support the excess weight.
--Shading issues: none except possibly from the roof parapets, which can be handled by proper panel positioning (no tall trees for miles around!).
--Inverter for Kyocera system: same as listed for Sunpower system.
--Less estimated output from Kyocera system: not due to shading, but instead based on their experience of somewhat lower energy production from Kyocera vs. Sunpower panels.
--Projected payback time: just under 9 years for either system assuming only the 30% federal tax credit (we will likely finish too late to qualify for any of the expiring 10% state tax credit money).

The length of the payback is long enough that I'm not sure this proposal makes economic sense. So I contacted 3 other Las Cruces area solar vendors for alternative quotes over a week ago but not one has yet gotten back to me. Maybe they don't need any more business!

[Yaryman]

--Projected payback time: just under 9 years for either system assuming only the 30% federal tax credit (we will likely finish too late to qualify for any of the expiring 10% state tax credit money).

The length of the payback is long enough that I'm not sure this proposal makes economic sense.

What is your average summer electrical bill? ( kWh and price )

Solar does make more economic sense the higher your electric rates.

I estimate my payback at just under 6 years.

If there is ANY CHANCE you might move, don't do solar. You will not get a nickel for your installation.

[renormalize]

What is your average summer electrical bill? ( kWh and price )

Solar does make more economic sense the higher your electric rates.

I estimate my payback at just under 6 years.

If there is ANY CHANCE you might move, don't do solar. You will not get a nickel for your installation.

Since we recently moved to a small rental in Las Cruces and our new larger house is not yet built, we have no relevant summer electric bill info. But the current local power rates are relatively low:

May-Oct (0-600 kWh) = $0.11790 per kWh
May-Oct (>600 kWh) = $0.13599 per kWh
Nov-Apr (All kWh) = $0.10970 per kWh

And we have no plans to ever move as this is to be our retirement home.

[Yaryman]

Since we recently moved to a small rental in Las Cruces and our new larger house is not yet built, we have no relevant summer electric bill info. But the current local power rates are relatively low:

May-Oct (0-600 kWh) = $0.11790 per kWh
May-Oct (>600 kWh) = $0.13599 per kWh
Nov-Apr (All kWh) = $0.10970 per kWh

And we have no plans to ever move as this is to be our retirement home.

I hate to say this, but at those prices it's hard to advise one to go solar.

And if you do go solar, please for the Love of Gosh don't spend the extra money buying Sunpower, it just makes NO FINANCIAL SENSE.

NONE, NADA, ZIP, ZERO, LESS THAN ZERO.

[YvetteI]

Who is the contractor quoting you on this system? Only reason I ask is because I know 2 contractors in the las cruces area and can possibly get you a lower price/ watt.