Hi All. I need some help with vastly different quotes.

[tigerucla]

I've learned lots reading on this site. Thanks to all who've posted. I have always thought solar wouldn't make sense for us because we've managed to lower our electricity use through other means. But with the possibility of the tax credit going away at the end of the year, I figured it's worth checking into. I guess it's now or never.

Our average monthly usage over the last year has been 640 KWH, and our average monthly bill $130. Of course it's much higher in the summer to cool our 3640 sq. ft. house.

We're looking to purchase (to take advantage of the tax credit), and we won't need to finance.

I got quotes from three companies today:
1- Capital City Solar- 14 Sunpower 327 watt panels with microinverters (4.58 KW total)- $21,288 (before tax credit)- estimated $0 monthly bill
2- Magic Sun Solar- 21 LG 285 watt panels with microinverters (5.985 KW total)- $19,362.77 (before tax credit)- estimated $24 monthly bill
3- Magic Sun Solar- 21 LG 320 watt panels with microinverters (6.72 KW total)- $22,512.00 (before tax credit)- estimated $11.61 monthly bill
4- Allphase Solar (young local company)- 17 Canadian Solar 290 watt panels with Optimizers (4.9 KW total)- $18,488 (before tax credit)- estimated $0 monthly bill

It seems to me that there is a large discrepancy in the size of the systems quoted, with the largest system not completely eliminating our average monthly bill. Is this because some systems are more efficient than others? Are Sunpower panels really that much more efficient? What can yo make of these numbers, and which looks the best to you?

Also, it looks like after the tax credit, our break even point will be somewhere around 8-10 years. Would that be good enough to make you pull the trigger?

Thanks!

Steve

[J.P.M.]

As you've spent a lot of time here, then you know what to do. As a refresher:

- Download or buy: "Solar Power Your Home for Dummies".
- Learn how you are charged for electricity and understand why the most cost effective system may not be one that offsets your entire bill. 7600 or so kWh*/yr. isn't much. You
- Download PVWatts. Read and understand the help screens. Then, do a few runs.

Have you done the above yet ?

After all that, decide what's best for your situation.

Not knowing where you are, it's difficult to comment on what you've been quoted. It looks like the system sizes are all over the board. Assuming all quoted systems will have the same orientation, and since most every system of equal size will produce about equal annual output, something may be amiss. Also, I hope you're in a cloudy climate because if you are in a sunny climate, even the smallest system is very oversized, making the larger ones worse.

Sunpower panels are good quality, but no more fit for purpose than the other equipment you've been quoted. All equal (electrical) size systems in the same location and orientation will, for all practical purposes, produce about the same annual kWh output. The "most efficient" B.S. hype Sunpower peddles refers to an AREA efficiency. So, 5 kW of sunpower panels will produce about the same annual output as a 5 kW LG or Canadian Solar panels, with the only differences being the 5 kW Sunpower system will take up about 20 % less space on your roof and cost (per your quotes) about 44 % more than the LG285 quote.

What a deal. Go back and reread prior posts. I've been ranting for literally years about how buying a Sunpower system is similar to buying a Mercedes when a Ford is needed as a grocery hauler. I'm surprised you missed the rants.

Your money/house/life/choice. I'd not buy anything without more homework. Quite honestly, with usage that low, you may very well have a hard time making any system cost effective if you using realistic and known assumptions and numbers. Also, the whole and very important issue of quote evaluation based on most bang for the buck, including the very important issue of vendor quality and something called vendor integrity hasn't even been mentioned yet. Getting solar PV is not simply about low initial price. That's the fools way. It's much more about getting equipment that's safe, fit to the task and assembled in a quality fashion, all for a fair and sharp. price - in short - a system that delivers most bang for the buck. That's a lot different than low buck.

What's your zip and what's your usage by month, and what orientations - azimuth and array tilt do you anticipate ?

[tigerucla]

Thank you J.P.M. It helps to hear you verify that the quotes are all over the board. It makes sense to me that panel watt ratings should comparable, but I thought I might have missed something. I like the analogy of Sunpower being like a Mercedes (but I prefer Honda or Toyota to Ford, myself). Would LG be considered a "more practical" vehicle? How about Canadian Solar? And where do you stand on microinverters vs optimizers?

To answer your questions, our zip is 95746. Our usage by month from Sept to May ranges from 450-600 kwh, June and July 800-1100, and August 650-700. We have a good south facing roof slope which faces about 175 degrees and which doesn't get any shade until about 4 pm, when it starts to creep across the roof starting at the lower left. I do not know what the slope of our roof is, but would roughly guesstimate it to be between 30-45 degrees.

I have skimmed through "Solar Power Your Home for Dummies". Much of seems like elementary physics, which I believe I have enough understanding of.

As for electricity rates, Tier 1 (427.8 kwh) is at .18; Tier 2 and 3 combined (427.8 kwh) is at .24; Tier 4 is at .40.

I understand that it's more cost effective to buy enough solar to eliminate the higher tiers, but I'm thinking 18 cents/kwh is not exactly cheap, and I can see scenarios where our electricity usage might go up in the future (electric vehicle?).

So here's what I'm thinking- an $18,000 system (if we can get it down that low) which virtually eliminates our electric bill would cost us $12,600 after tax credits. If we're saving $1,560/yr, that's an 8 year break even proposition. I'm thinking that might be worth it. That doesn't take into account rising electricity prices. And if it adds value to our home, all the better. Magic Solar gets great Yelp ratings (though no ratings on Solar Reviews) and should be priced about right for a 5 kwh system, which is about what I'm guessing we'd need for this scenario.

[solarix]

You are in a hot climate and all your quotes involve putting electronics on a hot roof - a big reliability risk. They are warrantied of course, but do you someday want someone having to come out month after month to replace them as they fail one by one? My advice is to get some quotes using Canadian Solar / Q-Cell / SunEdison / REC panels and either SMA / Fronius / or Conext inverters. Magic solar sounds suspicious, stick with someone from Solar Reviews - you have plenty to choose from in your area.

[tigerucla]

Thanks solarix. I assume you're talking about the microinverters being susceptible to the high heat? Would there be the same concern for optimizers?

[J.P.M.]

Thank you J.P.M. It helps to hear you verify that the quotes are all over the board. It makes sense to me that panel watt ratings should comparable, but I thought I might have missed something. I like the analogy of Sunpower being like a Mercedes (but I prefer Honda or Toyota to Ford, myself). Would LG be considered a "more practical" vehicle? How about Canadian Solar? And where do you stand on microinverters vs optimizers?

To answer your questions, our zip is 95746. Our usage by month from Sept to May ranges from 450-600 kwh, June and July 800-1100, and August 650-700. We have a good south facing roof slope which faces about 175 degrees and which doesn't get any shade until about 4 pm, when it starts to creep across the roof starting at the lower left. I do not know what the slope of our roof is, but would roughly guesstimate it to be between 30-45 degrees.

I have skimmed through "Solar Power Your Home for Dummies". Much of seems like elementary physics, which I believe I have enough understanding of.

As for electricity rates, Tier 1 (427.8 kwh) is at .18; Tier 2 and 3 combined (427.8 kwh) is at .24; Tier 4 is at .40.

I understand that it's more cost effective to buy enough solar to eliminate the higher tiers, but I'm thinking 18 cents/kwh is not exactly cheap, and I can see scenarios where our electricity usage might go up in the future (electric vehicle?).

So here's what I'm thinking- an $18,000 system (if we can get it down that low) which virtually eliminates our electric bill would cost us $12,600 after tax credits. If we're saving $1,560/yr, that's an 8 year break even proposition. I'm thinking that might be worth it. That doesn't take into account rising electricity prices. And if it adds value to our home, all the better. Magic Solar gets great Yelp ratings (though no ratings on Solar Reviews) and should be priced about right for a 5 kwh system, which is about what I'm guessing we'd need for this scenario.

You're welcome.

I don't verify. I simply spew opinions that 1X/a while may be taken as verification when there is agreement.

FWIW, there's a lot more in the book I referenced dealing with common sense stuff than I've found in most of the Physics texts I've read/used.

Since solar panels are becoming a commodity, like dishwashers, garage door openers and porn, as long as you stay away from unknown crap, you may find quality, longevity and performance are all about the same, probably +/- some small amount. That makes the issue of vendor quality - always large but often given the short end of the stick - now even more important.

I'm not a fan of micro inverters - too many failure points and so a potentially larger PITA if problems develop. IMO only, the KISS principle applies here. Same thing, but maybe a bit less adamantly to optimizers.

On POCO rates/tariffs: If your POCO is one of the IOU's that's affected either directly or indirectly by AB 327/rate reform, know that tiered rates will be ending if you do not make the NEM 1.0 cutoff, which may/may not be close at hand for you or already a thing of the past. That's part of what I was referencing when I suggest you get familiar with how you are billed. If/when you go to T.O.U. billing, you may well find, if you do the homework, that your hourly as well as monthly use pattern(s) may result in a situation where a system sized for a cost effective offset on a tiered rate is not the same size as one sized for most cost effective for a T.O.U. tariff.

If you stay on tiered rates (with that looking like a bigger for the longer term), I'd guess that about half or more of your 7,500 -8,000 kWh/yr. is at tier one billing. For a system the size you're looking at, even at, say, 12,000 kWh/yr. w/an EV (maybe/someday/??), getting a LCOE for PV supplied power below the LCOE that $0.18/kWh POCO power might yield (which will probably not be $0.18/kWh depending on your assumptions used to get an LCOE for either source) on a 100% offset can be a challenge.

So, a crap shoot scenario: Offset 7,500 kWh/yr., and gamble on a future EV (or use the proposed/possible EV acquisition as a justification for a less than cost effective PV size than current usage might justify). Or, go with about an 80% or so offset to current and probably future use (if no EV), or whatever size gives the lowest LCOE combo of POCO/PV mix, and perhaps be undersized if an EV comes into your future. Sort of depends on how certain you are of an EV.

I'm unfamiliar w/ installation costs in your area, but $18K for a 5 kW system doesn't seem out of line from what others in No CA seem to report, provided you get that from a quality vendor.

A SWAG w/PVWatts gives ~ 1,500 kWk/yr., maybe a bit less depending in particulars and the shading you report per installed kW.

Pay your money - take your choice. Just walk in with your eyes and mind open and knowledgeable as to options and consequences as well as opportunities, pitfalls and how the game is run.

Good luck.

Take what you want of the above. Scrap the rest.