SunPower vs LG System?

[J.P.M.]

FWIW, I own a S.P. system, but my choice had nothing to do with economics. Long, boring story. If it had, I could have gotten equal or better performance for about a buck a Watt less before tax credit.

I've monitored ~ 100 system installs for my HOA and keep track of performance for several of them. When adjusted for orientation and some shading, output per installed STC kW is about the same for all systems, including mine. My own system's output is about 1,780 or so kWh/yr. per STC kW.

Check PVOutput for systems near you for reasonably unbiased estimates of systems' outputs. My S.P. output is about the same as other similarly oriented nearby systems., sometimes less.

As for warranty claims, my experience is that panels tend not to fail. There are about 1,400 -1,600 separate panels in my HOA of all stripes/mfg. Over the last 9 or so yrs. I've been keeping track, I think there has been 1 panel failure and that was a fluke that happened on/around startup and a couple others due to wiring screw-ups. There was one golf ball strike.

Sunpower's good stuff, but so is a Mercedes. Solar panels are now a commodity. A Ford is as good a grocery hauler as a Mercedes in terms of fit for purpose. LG or most any quality panel is as fit for purpose as S.P. LG or the others just doesn't come with bragging rights or snob appeal.

Pay your money. Take your choice.

[emartin00]

JPM makes some excellent points. Failures of panels is extremely rare these days. If they do fail, it's usually early on, due to manufacturing defect, and that is what the warranty is for.
The degradation warranty is something I would imagine would be very difficult to warrant new panels. You would have to take the panel off of your roof, send it back to the manufacturer, and let them test it. If it still is within spec, you just wasted a couple hundred bucks in shipping.

I have no problem with Sunpower if you need that efficiency. But as many others have said, you can get the same power output significantly cheaper from a number of reputable companies.

[littleharbor]

Sunpower brown cells 2 (2).jpg Here's something to keep an eye out for with Sunpower modules,

http://guntherportfolio.com/2013/03/new-sunpower-solar-cell-discoloration-anomalies-at-the-photovoltaic-demonstration-project/

I've had some Sunpower Modules with this anomaly. If your rooftop system were clearly visible these "browned out" cells would be pretty butt-ugly for all to see.

[littleharbor]

Another view, Sunpower brown cells (2).jpg

[Ian S]

The degradation warranty is something I would imagine would be very difficult to warrant new panels. You would have to take the panel off of your roof, send it back to the manufacturer, and let them test it. If it still is within spec, you just wasted a couple hundred bucks in shipping.

It's not so much the warranty with regard to degradation, it's that the degradation spec itself is better and, over time, SunPower panels will produce more energy than panels with a higher degradation rate. That better performance will offset at least some of the initial price premium.

[musklover]

I agree with Ian...I got my panels from SunPower and have had no complaints. However, I am based in Colorado so the tax credits might be different? I got 30% federal tax credit and I get rebates from my utility company. Unfortunately, utility companies have started charging higher utility rates for those who have solar panels.. damn them!! > monopolistic companies...
So I would definitely look into that before getting solar. I just the info on this for California: https://www.solarpowerauthority.com/home-solar/ca

[J.P.M.]

It's not so much the warranty with regard to degradation, it's that the degradation spec itself is better and, over time, SunPower panels will produce more energy than panels with a higher degradation rate. That better performance will offset at least some of the initial price premium.

Ian: First, Happy Holidays. Where/How Ya' been?

Next: I suppose I'd want to have some numbers to verify any performance suspicions I may have. How does one identify annual degradation in the field ? How does one measure it ? All panels in an array or just some ? Without micros, how to determine which ones ?
Who pays the freight to the testing site ?
Who pays what if any of the product is found to be within spec?
As for aesthetics, I'm not sure which if any, panel mfgs. consider appearance to be a warrantable product feature.

[miracj]

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?

SunPower now has AC panels (essentially their panels with their own micro-inverter stuck on the back). This is your solution if you want to use one of their 300 watt plus panels. For myself, I had limited roof space (well enough for 40-ish panels anyway) to generate my 13000 KwH/year needs, so I went with SunPower AC panels with their 345 watt panels. The warranty and less degradation had to be weighed with the current cost of electricity ($0.20/kwh) and it's future cost, the length that the panels and micro-inverters last, the drop in cost for panels over time, compounded interest for the extra spent over time, federal and state credits, SRECs etc.

For my state and tax bracket, I got a 30% reduction in the 1st $35,000 dollars, 1% loan for 10 years for the 1st $35,000 dollars, 30% federal credit for the full cost, plus SREC payments for 10 years. Depending upon actual production (system is new), and the average price of SREC payments, breakeven point for me is 1 to 3.5 years.

As for Micro-inverter vs string inverter, I feel that even though micro-inverters add more points of failure, a failure only affects 1 or 2 panels, not the whole system. String Inverters have a shorter lifetime, and don't accommodate shading. While the power optimizer solution is more reliable than micro inverters (I'm an electronic engineer) on paper, Solaredge is a smaller company, and thus there is some risk there, and have a lot less # of units out on the market than say, Enphase, and thus have less field experience with them. In addition power optimizers, while dealing with shading (and better than Enphase micro-inverters, not sure about the rest) also still need a string inverter, so you lost that advantage. But of course YMMV.

I'd argue that all you really need is to figure your breakeven point, and everything after that is gravy!

Edit:
Also, one other item harder to calculate (because you can't always get the numbers from the install company) is the cost of installing less higher power panels vs more lower power panels) to get the same effective power, and the increase of failure when you add more panels vs less for either the micro-inverters or string inverters.

[Ian S]

Ian: First, Happy Holidays. Where/How Ya' been?

Next: I suppose I'd want to have some numbers to verify any performance suspicions I may have. How does one identify annual degradation in the field ? How does one measure it ? All panels in an array or just some ? Without micros, how to determine which ones ?
Who pays the freight to the testing site ?
Who pays what if any of the product is found to be within spec?
As for aesthetics, I'm not sure which if any, panel mfgs. consider appearance to be a warrantable product feature.

Happy Holidays to you too J.P.M.! I guess after 4 1/2 years, I find myself kinda taking my solar for granted. I haven't bothered cleaning the panels for a year especially since the new HVAC system has put my electric consumption back to the point where my trueup (which occurred today) leaves hundreds of peak kWh's to be compensated @ a measly $0.029/kWh. So I'm in a sweet spot where I don't pay for any peak kWh at all throughout the year and saving some off-peak kWh's @ ~$0.07/kWh doesn't seem worth the risk to life and limb that I take in going up on my roof for regular cleanings. I still plan to put some bird spikes along the upper panel edges but there are a number of other outdoor home maintenance tasks that have jumped to the top of my winter to-do list!

With regard to the panel degradation, I agree that the warranty would be hard to enforce and in any event, allows for much more degradation than would probably ever happen. My point was that the degradation specification for SunPower panels is superior to other panels even high quality ones like LG. Assuming we can trust such specs from any manufacturer, the difference in energy produced per watt can be significant over the lifetime of the panel system - possibly amounting to between 5 and 10%, perhaps more depending on the difference in spec values of degradation rate and what's considered the life of the product. The degradation occurs both initially and over the long term. LG brags about improving their Mono X2 initial LID (light induced degradation) from -3% to -2% and their long term degradation from -0.7% to -0.6% per year but SunPower specs no initial LID and a -0.25% per year long term degradation rate. Now, can such superior performance over the life of the panel fully offset the higher initial cost of the SunPower panels? Perhaps not but it certainly makes them more competitive and, IMHO, worth considering at least.

Meanwhile, time flies: only 16 months until my buyout date!

[SunEagle]

SunPower now has AC panels (essentially their panels with their own micro-inverter stuck on the back). This is your solution if you want to use one of their 300 watt plus panels. For myself, I had limited roof space (well enough for 40-ish panels anyway) to generate my 13000 KwH/year needs, so I went with SunPower AC panels with their 345 watt panels. The warranty and less degradation had to be weighed with the current cost of electricity ($0.20/kwh) and it's future cost, the length that the panels and micro-inverters last, the drop in cost for panels over time, compounded interest for the extra spent over time, federal and state credits, SRECs etc.

For my state and tax bracket, I got a 30% reduction in the 1st $35,000 dollars, 1% loan for 10 years for the 1st $35,000 dollars, 30% federal credit for the full cost, plus SREC payments for 10 years. Depending upon actual production (system is new), and the average price of SREC payments, breakeven point for me is 1 to 3.5 years.

As for Micro-inverter vs string inverter, I feel that even though micro-inverters add more points of failure, a failure only affects 1 or 2 panels, not the whole system. String Inverters have a shorter lifetime, and don't accommodate shading. While the power optimizer solution is more reliable than micro inverters (I'm an electronic engineer) on paper, Solaredge is a smaller company, and thus there is some risk there, and have a lot less # of units out on the market than say, Enphase, and thus have less field experience with them. In addition power optimizers, while dealing with shading (and better than Enphase micro-inverters, not sure about the rest) also still need a string inverter, so you lost that advantage. But of course YMMV.

I'd argue that all you really need is to figure your breakeven point, and everything after that is gravy!

Edit:
Also, one other item harder to calculate (because you can't always get the numbers from the install company) is the cost of installing less higher power panels vs more lower power panels) to get the same effective power, and the increase of failure when you add more panels vs less for either the micro-inverters or string inverters.

I would be hesitant to go with SunPower based on some of what I see in the news about them shedding 1/4 of their staff and cutting costs.

[J.P.M.]

Happy Holidays to you too J.P.M.! I guess after 4 1/2 years, I find myself kinda taking my solar for granted. I haven't bothered cleaning the panels for a year especially since the new HVAC system has put my electric consumption back to the point where my trueup (which occurred today) leaves hundreds of peak kWh's to be compensated @ a measly $0.029/kWh. So I'm in a sweet spot where I don't pay for any peak kWh at all throughout the year and saving some off-peak kWh's @ ~$0.07/kWh doesn't seem worth the risk to life and limb that I take in going up on my roof for regular cleanings. I still plan to put some bird spikes along the upper panel edges but there are a number of other outdoor home maintenance tasks that have jumped to the top of my winter to-do list!

With regard to the panel degradation, I agree that the warranty would be hard to enforce and in any event, allows for much more degradation than would probably ever happen. My point was that the degradation specification for SunPower panels is superior to other panels even high quality ones like LG. Assuming we can trust such specs from any manufacturer, the difference in energy produced per watt can be significant over the lifetime of the panel system - possibly amounting to between 5 and 10%, perhaps more depending on the difference in spec values of degradation rate and what's considered the life of the product. The degradation occurs both initially and over the long term. LG brags about improving their Mono X2 initial LID (light induced degradation) from -3% to -2% and their long term degradation from -0.7% to -0.6% per year but SunPower specs no initial LID and a -0.25% per year long term degradation rate. Now, can such superior performance over the life of the panel fully offset the higher initial cost of the SunPower panels? Perhaps not but it certainly makes them more competitive and, IMHO, worth considering at least.

Meanwhile, time flies: only 16 months until my buyout date!

Thank you. It seems you had a horseshoe in you butt he day you signed that lease.

I'm not real trusting of most claims on performance/degradation, especially when verification is next to impossible which seems to me to remove most of the consequence of getting caught making unverifiably optimistic claims. But, I,m probably more skeptical and cynical than most.

As for S.P. and their warranty, first off, a lot can happen in the first 6 months after mfg. Then, item 2a of the published warranty and the S.P. definition of minimum peak power contained therein would seem to me go a long way to covering their butts for any light induced (burn in) degradation.

[miracj]

I would be hesitant to go with SunPower based on some of what I see in the news about them shedding 1/4 of their staff and cutting costs.

Well that certainly doesn't bode well for them. There are always losers in any competitive industry, so one need to weigh carefully the viability of the company. I look forward to a future where all the parts from all companies are built to the same standards, so that the parts become interchangeable. Whether that ever could happen, I doubt it, but it would either be led by a maverick leader like Tesla or government regulation if it did.

[Ian S]

As for S.P. and their warranty, first off, a lot can happen in the first 6 months after mfg. Then, item 2a of the published warranty and the S.P. definition of minimum peak power contained therein would seem to me go a long way to covering their butts for any light induced (burn in) degradation.

The more costly N-type silicon technology used by SP is what gives them their resistance to light degradation. Other manufacturers are moving to N-type away from P-type silicon which exhibits the LID due to the reaction of traces of Boron with oxygen. N-type silicon has no boron. It also has some other advantages and in the future, SP will have more competition as others switch to that technology.

[SunEagle]

The more costly N-type silicon technology used by SP is what gives them their resistance to light degradation. Other manufacturers are moving to N-type away from P-type silicon which exhibits the LID due to the reaction of traces of Boron with oxygen. N-type silicon has no boron. It also has some other advantages and in the future, SP will have more competition as others switch to that technology.

As long as it doesn't raise the cost of the final product.

Not sure if SP's panels cost more because of the N type or because they feel they can just get away with the higher price. Unfortunately it looks like the lack of sales has hurt the company even if it does have a better mousetrap.

[Ian S]

Not sure if SP's panels cost more because of the N type or because they feel they can just get away with the higher price.

Maybe both. It seems the price gap has narrowed: the O.P.'s quotes show SP at only $3.66 per watt vs $3.24 for the LG. Or maybe prices really have dropped that much. Can SP survive? Can anyone survive? If LG or any other conglomerate for that matter wanted to they could jettison their solar business in a heartbeat. Will Total have more patience with SP? Who really knows?