SunPower vs LG System?

[cambyses]

Hello All,

New to forum, and considering one of the following two systems for our house in Southern CA:

System 1:
24 x 320W LG panels with Enphase S280 microinverters
Price (prior to tax credit): ~$24,900

System 2:
22 x 360W SunPower panels (w/ integrated microinverters)
Price (prior to tax credit): ~$29,000

My question is which system would you choose, and why? Specifically: a) Do these prices look attractive?, and b) which system seems like a better deal overall?

Thanks...

[solar pete]

Hi cambyses and welcome to Solar Panel Talk. Well I would choose neither of those options. If it were me I would be asking installers for a quote on Canadian 280 with SMA inverter. Opinions do vary. I like the traditional SMA string inverters, they are very well built and if there is ever an issue we have found SMA to be the best inverter manufacturer to deal with. While SunPower is good stuff in my opinion they are not worth the huge premium over the other tier 1 panels, cheers.

[cambyses]

Thanks a lot Solar pete for the response...

In regards to SunPower, for the two systems I mentioned, the premium does not seem too huge to me. Specifically, accounting for the system size difference between the two, and the 30% federal tax credit, the net post-tax-credit delta between the two systems would be ~$2300. So my question is if it would be worth paying ~$2300 premium for the SunPower system compared with LG?

Thanks again...

[solar pete]

In my opinion no

[Sunking]

There is nothing special about Sun Power. They are just like Apple. Nothing special, just way over priced and good ole fashioned brain washing. You can get better panels than SP for less money, a lot less money.

[SunEagle]

I agree with solar pete and Sunking. IMO the Sunpower system it isn't worth the extra cost no matter what claim is made.

[baadls1]

System A, but only if needing to mitigate shading. I like the idea of a string inverter over managing several points of failure (micro inverters) and a company with uncertain financials.

[J.P.M.]

Appearance will be about the same. For the same location and orientation, annual output per installed STC Watt will be about the same, LG may even do a bit better.
The alleged superior S.P. Warranty is not worth $0.42/Watt. 5% MAYBE - more than that probably not. $0.42 - no way.
The S.P. hype touting "most efficient" is simply B.S. - that's an area efficiency - not a cost of production efficiency.
Unless the price difference is < 5%, LG's the more cost effective choice.

And - unless you've got shade, skip the micro inverters for a string inverter and reduce the number of potential failure site and roof mounting of electronics in harsh environments and limited access locations - probably for less money as well.

[emartin00]

The premium for Sunpower doesn't seem like a lot, because you are comparing it to another premium brand.
Sunpower and LG are the 2 highest efficiency, but also highest cost/watt modules. If you have the space for more panels, another brand would likely end up being cheaper.

Do you have any shading issues? If not, I would go with a traditional string inverter. I personally prefer optimizers over micro inverters, but they both work if you have shading.

[cambyses]

Thanks everyone... Not much love for SunPower on this forum apparently...

In regards to panel efficiency delta, yes, I do understand that it is not output efficiency, since that has already been taken into account in the rated Watt for the given panel. So it effectively would translate into delta in area efficiency, which would become irrelevant unless there is roof space limitation.

There is however also some delta in guaranteed degradation/de-rating. Specifically, this is what SunPower Warranty says:

"...the power output of the PV Modules will be at least 95% of the Minimum Peak Power2 rating for the first 5 years, and declining by no more than 0.4% per year for the following 20 years, so the power output at the end of the final year of the 25 year warranty period will be at least 87% of the Minimum Peak Power rating."

whereas LG Warranty reads as:
"...power output will decline annually by 0.7% in each of the remaining 24 years, so that during 25th year, an actual output of at least 80.2% of the nameplate power output specified on the Module will be achieved"

Obviously, any warranty would be as good as the company behind it. But putting that concern aside, and assuming ~13000 KWh generated by both systems in the first year, in year 25, LG will generate 10426 KWh while SunPower will generate 11310 KWh. Doing a linear average over the 25 years, LG would produce 11713 KWh per year vs. 12155 KWh per year for SunPower. So 442 KWh per year delta adding up to 11050 KWh delta over 25 years. Assuming a rate of 30c/KWh, that would be $3315 over 25 years. One might say 25 years would be too long of a period to consider for this analysis, and I would agree. But I am just highlighting that the cost effectiveness in these comparisons may not be so clear cut.

In addition to de-rating, there is a small Temp Coeff delta between SunPower and LG as well. (-0.3% per degC for S.P. 360W vs. -0.38% per degC for LG 320W panels, according to their respective datasheets). This would not make much difference in output for us here in Southern CA, but it could make some difference in areas with extreme temp changes.

And then there is S.P. vs LG warranty differences; specifically 25 years product warranty, including labor warranty vs 10 years for LG with no labor warranty. Again, I understand that SunPower may not be around that long, and same can probably be said about LG remaining in Solar business (though I think I would give a higher chance for SunPower going out of business).

All this is what has made my decision on paying ~$2300 premium for S.P. a bit more difficult. I should note that I will be purchasing the system and I do currently plan to keep the house.

In regards to a central inverter vs microinverters, of course, I guess that would not be an option for me if I decide on S.P. 360W panels. But in general, besides part of my roof getting into shade during part of the day (depending on the season), isn't scalability also another advantage of the micro-inverters? Namely, if we add a couple of Electric cars down the road and want to add more panels then?

Thanks again for all your inputs...

[cambyses]

To add yet another angle, what do you guys think of Panasonic 330W panels? They seem to have slightly better specs and better product warranty (15 yrs vs 10 yrs) than the LG panels but offered at similar price.

[J.P.M.]

On the worth of the POSSIBLE (but effectively impossible to verify) extra (or deficient for that matter) S.P. output over any future period: The accurate way to do it is compare the net present value (NPV) of any possible or expected output of the S.P. system vs. the possible or expected future output of the LG, or any other system. If, any expected additional future savings have a NPV => than the extra S.P. system cost, then the S.P. system is the better choice. Or, a second way to do it: Take the savings by buying the LG system and look around for some other semi liquid investment that will, when left untouched for the same time period, have some probability of producing the same future value as the future value of the possible future additional output of the S.P.system.

Most folks eyes glaze over when such things dealing with NPV or time value of money analysis is involved, which is pretty much what the S.P. folks bet on to sell the premium for their product. But, similar to the value of compounding you may have heard about, things change more than simple +,-,*,/ when time enters the equations.

Usually, with a set of realistic assumptions on such things as time frames, possible (?? - crap shoot - both ways, up and down) electric rate increases, and alternate financial instrument investment rates, and in the end, no more than FWIW, I figure if a S.P. system can be installed for no more than 5 % or so more than a competing system, it's a wash. Any more than that, S.P. is not justified from a cost standpoint with a fair consideration for the ideas, as a practical matter, and based on some measurement and observation, output will be essentially equal for most any quality system for as long as most folks will own it, panel reliability will be about the same, one mfg. to the next and resale value (if any) will be about equal, as will maintenance costs.

But, opinions vary. Some are more informed is all. Knowledge is power.

[Mike90250]

Thanks everyone... Not much love for SunPower on this forum apparently.....

It's because they sell moondust, when most folks are just fine with plain dust, IF you have limited space, and IF you need every last bit of power, then I would consider them.
And the other option is to add one or two plain jane panels, and have the same overall harvest or more....

Micro inverters have their scaleability issues, along with a problem they output power at 240V instead of 450-550V and require larger wire gauge and are more prone to tripping off-line from high AV voltage.
To add just one more panel & inverter, requires a new permit and Grid agreement,

[Ian S]

To add yet another angle, what do you guys think of Panasonic 330W panels? They seem to have slightly better specs and better product warranty (15 yrs vs 10 yrs) than the LG panels but offered at similar price.

Don't be put off SunPower. While the higher efficiency spec is usually not any advantage for most rooftops, the better degradation performance, IMHO, narrows the price gap significantly. Especially if you consider that the lifetime of the panels is far greater than 25 years and that degradation advantage is apt to continue well beyond the 25 year mark. The warranty is nice too but maybe just icing on the cake.

[Sunking]

Thanks everyone... Not much love for SunPower on this forum apparently...

Not if you understand most of the negative comments come from the pros which ought to tell you something valuable. Those that recommend SP are customers to embarrased to admit they made a mistake, and installation contractors who install the panels. Small crowd.

LG and SP are good panels. No one is saying otherwise. What we are saying is they are not worth the price they are asking because you can buy = or better panels for significantly less than both LG and SP.

As a consumer making such an investment, I want to find a company that will be around 20 years from now after the Solar Bubble bust. I would not want to use a company who have a very limited products line restricted to Solar Panels like SP. I want a company where solar is just a side show and solar makes up a very small percentage of their product line. Names I know and trust that have been around a long time and will be around tomorrow to honor their product and warranty. Names like Panasonic Sanyo, GE, Kyocera, and even LG. Companies that only make panels will go bankrupt when the bubble burst never to be seen again Many have already gone bust.