Is Sunpower price difference worth it? -- thoughts, posting as new topic

[J.P.M.]

J.P.M., how many Solar Panel owners have a clamp meter? I don't.

Don't know. Probably not many. Seems like Bruce does. I know I do, but don't use it much.

[ButchDeal]

And that is why, when designing a string inverter system, it is best to specify two smaller inverters rather than one large inverter. Yes the cost is slightly more but the two inverter design has advantages. As Bruce mentioned above in tracking down problem panels but also if a panel does go down it does not affect the entire array since one half will be fully functioning while the other half is diminished or down for repair.

But I think the greatest advantage is that the problem is recognized immediately since the the inverter outputs can be compared daily, of course, with the right monitoring system.

Seems silly to me, lots of added electrical wiring, more complex rapid shutdown etc. just go with solarEdge and not only is it emediatly identified, with an email and notification, but you can see exactly were the problem is.

[J.P.M.]

Seems silly to me, lots of added electrical wiring, more complex rapid shutdown etc. just go with solarEdge and not only is it emediatly identified, with an email and notification, but you can see exactly were the problem is.

Sounds like another common sense, practical solution provided SolarEdge is the equipment choice.

[MarkH180]

Agree SolarEdge is a good option with Sunpower or other panels to be able to see panel-by-panel monitoring

..Also in practical terms all a homeowner needs is online monitoring system and to know what is the acceptable annual kWh per year expected production for their system (various online tools out there, and combining with the tools the contractor you choose uses to make similar annual production estimate), divide by 365 to get to per day to have a rough idea that in summer systems produce about 125 to 130% of the average (average being Spring/Fall), and in the winter 50% or less of the average on a sunny day. There's no quick way for an average homeowner to know when a shortfall is happening, short of central inverter going out or paying attention occasionally to online monitoring for micro-inverters or SolarEdge optimizers for panel-by-panel monitoring, combined with just practical occasional tracking of how their own system is performing in general via monitoring/inverter(s)

One factor I do think about and I think goes on the value side of the equation for Sunpower, (along with other value points that I think a homeowner wouldn't necessarily be a "sucker" for paying $2,500 extra for on 5.2kW system -- ie company history/size/strength which lowers probability of going out of business, efficiency, method of panel construction/quality, mentioned in earlier posts in this string)

-- is in the "worst case" contractor out of business scenario , Sunpower has made itself to be one of the easiest manufacturers to contact directly and test for proper system operation because they have so many local dealers in CA, their warranty covers 25 yrs full module replacement parts/labor if defective, and from what I've read they don't require a flash test to determine if module is defective -- but a more simple volt meter / irradiance meter test that can be done by an authorized dealer, after pretty easily determining at the inverter which string(s) of panels reads low, or via SolarEdge panel-by-panel monitoring if that method is used on your system.

Overall, the homeowner's concern is risk of an under-producing system, especially significantly under-performing system. General knowledge of what to expect from the system in different seasons, or mainly during spring/fall/summer to make observation easier, and annually, and checking inverter status light / monitoring system occasionally are enough for a homeowner to know when something really looks like it's under-performing. You call your contractor first to check it out if they're a good contractor and still in business. And if they're out of business, you call the module manufacturer (or even independent electrician or other installer that knows how to do basic solar trouble-shooting) to find the problem.

[J.P.M.]

Agree SolarEdge is a good option with Sunpower or other panels to be able to see panel-by-panel monitoring

..Also in practical terms all a homeowner needs is online monitoring system and to know what is the acceptable annual kWh per year expected production for their system (various online tools out there, and combining with the tools the contractor you choose uses to make similar annual production estimate), divide by 365 to get to per day to have a rough idea that in summer systems produce about 125 to 130% of the average (average being Spring/Fall), and in the winter 50% or less of the average on a sunny day. There's no quick way for an average homeowner to know when a shortfall is happening, short of central inverter going out or paying attention occasionally to online monitoring for micro-inverters or SolarEdge optimizers for panel-by-panel monitoring, combined with just practical occasional tracking of how their own system is performing in general via monitoring/inverter(s)

One factor I do think about and I think goes on the value side of the equation for Sunpower, (along with other value points that I think a homeowner wouldn't necessarily be a "sucker" for paying $2,500 extra for on 5.2kW system -- ie company history/size/strength which lowers probability of going out of business, efficiency, method of panel construction/quality, mentioned in earlier posts in this string)

-- is in the "worst case" contractor out of business scenario , Sunpower has made itself to be one of the easiest manufacturers to contact directly and test for proper system operation because they have so many local dealers in CA, their warranty covers 25 yrs full module replacement parts/labor if defective, and from what I've read they don't require a flash test to determine if module is defective -- but a more simple volt meter / irradiance meter test that can be done by an authorized dealer, after pretty easily determining at the inverter which string(s) of panels reads low, or via SolarEdge panel-by-panel monitoring if that method is used on your system.

Overall, the homeowner's concern is risk of an under-producing system, especially significantly under-performing system. General knowledge of what to expect from the system in different seasons, or mainly during spring/fall/summer to make observation easier, and annually, and checking inverter status light / monitoring system occasionally are enough for a homeowner to know when something really looks like it's under-performing. You call your contractor first to check it out if they're a good contractor and still in business. And if they're out of business, you call the module manufacturer (or even independent electrician or other installer that know how to do basic solar trouble-shooting) to find the problem.

I gave up contacting S.P. about 6 months after my system was turned on. My requests to S.P. via e-mail were not responded to. When subsequent phone conversations were met with bobble head type responses from incompetent people who had a hard time with the English language, and promised e-mail responses never happened. Similar experiences occurred on 2 other occasions. I've no beef with my vendor or the system's performance, but, to my experience S.P's customer relations are substandard. Such experience does not make me optimistic that their warranty service
is any better. But, maybe I'm too harsh. The stuff is so good, that maybe their service dept. is like the lonely Maytag repair man waiting for the phone to ring.

As for what you may have heard about warranty claims, it's worth about what it's written on. Read the warranty.

[inetdog]

Don't know. Probably not many. Seems like Bruce does. I know I do, but don't use it much.

I do too (Sears).

[samotlietuvis]

Yes - Sunpower is worth it, but now more than $.75/W over next best brand panels like LG. As far I am aware they are they most efficient, best looking, most reliable panels with best shading performance. I have 17 E20-327W and 6X Suniva 325W, and Sunpower is a much better looking and smaller panel that performs better...

[samotlietuvis]

Yaryman, read "SunPower Module Degradation Rate" pdf document.

Given extremely low failure rate of Sunpower panels I don’t see a need for panel by panel monitoring. BTW, power optimizers add complexity and cost that I do not want on my roof…

My SMA Sunnyboy inverter outputs string Voltage and Current over time - that's more than enough for me to see if everything is kicking well...

Bruce, thanks for responding. What is sounds like you are telling me is 99% of people would not know their Sunpower panels had gone bad.

My system is still pretty new, and I look at the PV outputs everyday. It's easy and fast. In the city where I live there are at least 500 residential solar installations.
Only 3 are on pvoutputs. Myself and the other 2 are members of this board.

Most people have very little tracking software, and even fewer use it. I rarely ever check the enphase Individual panel output display. No reason to.
Using the method you described is impossible if the string arrays aren't exactly equal. I would bet most 2 string systems are not exactly equal.

My conclusion.

So it's very unlikely a Sunpower panel will fail.
So it's really, really, unlikely you will detect a Sunpower panel has failed.
So what did that extra $2500 you paid for get you?

I guess you had better had really enjoy those Sunpower commercials. YOU PAID for them.

Sorry, but if you don't have the ability to do this is 15 seconds, you are NOT going to check your panel outputs.

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[Yaryman]

My SMA Sunnyboy inverter outputs string Voltage and Current over time - that's more than enough for me to see if everything is kicking well...

If over time, one of those 17 Sunpower panels dropped to 75% production vs the other panels, you are claiming you would know?

How? You have no baseline you can compare the output to. How often do you check the sting voltage and current?

How would you know which one went bad? Are you going to call your installer and ask them to check each panel cause you think production is down 25% on one?

[solar pete]

If over time, one of those 17 Sunpower panels dropped to 75% production vs the other panels, you are claiming you would know?

How? You have no baseline you can compare the output to. How often do you check the sting voltage and current?

How would you know which one went bad? Are you going to call your installer and ask them to check each panel cause you think production is down 25% on one?

I would know if I had an issue with my system, after looking at it a lot over several years I pretty much know what to expect, ok I will do a live experiment its 12.37 pm here in SA its 28 dgree;s I ill guess my little array will be pumping out around 1400 watts, now I will run outside to check.....its 1451watts.....I consider that good enough for me

[sensij]

If over time, one of those 17 Sunpower panels dropped to 75% production vs the other panels, you are claiming you would know?

How? You have no baseline you can compare the output to. How often do you check the sting voltage and current?

How would you know which one went bad? Are you going to call your installer and ask them to check each panel cause you think production is down 25% on one?

On paper, it seems like it would be easier to identify a panel that has gone bad with a microinverter or SolarEdge system. In practice, if you look over the forum content of the past couple years, it looks like the only failures that have been identified are with the panel level electronics themselves (micros or optimizers). When the tool you are hoping will help find problems is the one creating them, that isn't very good.

I'm not sure what the right answer is... there are tradeoffs to every system currently on the market today. All I can suggest is to get educated about the strengths and weaknesses of each and choose what is likely to be the best fit for you.

[Yaryman]

I would know if I had an issue with my system, after looking at it a lot over several years I pretty much know what to expect, ok I will do a live experiment its 12.37 pm here in SA its 28 dgree;s I ill guess my little array will be pumping out around 1400 watts, now I will run outside to check.....its 1451watts.....I consider that good enough for me

So the Forum Administrator of the most popular Solar Forum in the known solar system has a pretty good read on his solar production.
( triple word score for using the word solar three times in one sentence )

Sorry to give you the bad news, but you aren't they typical residential solar panel owner. Not by a long shot.

[bcroe]

If over time, one of those 17 Sunpower panels dropped to 75% production vs the other
panels, you are claiming you would know?

How? You have no baseline you can compare the output to. How often do you check the sting voltage and current?

How would you know which one went bad? Are you going to call your installer and ask them to check each panel
cause you think production is down 25% on one?

Sure there is a baseline, use another string. Even if a different length, with the same orientation (and no shade)
the outputs will be directly proportional, assuming each has its own MPPT.

If one panel in a string fails, the output of the string will drop. If you study up on panel curves, you will see that a panel
or maybe 1/3 of a panel will be bypassed, causing the rest of the string to ramp up their voltage (to match another
parallel string) and drop current. I have detected 1/3 panel not keeping up in a string of 10. Once the failure is
detected, tracking down the panel is on the same level of difficulty as replacing it.

In addition, you will find that the MPPT voltage of a panel varies little, mostly with temperature. Variation are
not hard to spot. Of course all this is a lot easier with a ground mount; difficult access might justify more elaborate
monitoring. But in the bigger picture, the panels are the thing least likely to fail. All the other stuff can and will fail,
and panel monitoring won't pinpoint the issue. The simplest system able to serve the situation will be the most reliable.

Some people drive a car, some change the oil, that is fine. I rebuild my automatic transmissions. Not everybody
is up to system operational details or hands on with meters and dangerous wiring. So a fancy software monitoring
system can help compensate, but in the end it will rarely be used or needed for fault finding. Production over time
is a simple occasional number off your inverter display, which is more accurate than the individual monitoring since
it also takes into account DC wiring losses. Bruce Roe

[solar pete]

So the Forum Administrator of the most popular Solar Forum in the known solar system has a pretty good read on his solar production.
( triple word score for using the word solar three times in one sentence )

Sorry to give you the bad news, but you aren't they typical residential solar panel owner. Not by a long shot.

It doesnt matter, the point is that after looking at my solar system practically everyday and at various times of the day over several years, I have come to be able to predict quite acuratly what my system will be producing , anyone will be able to do that after enough time, well ok a lot of people will be able to work it out. Like many thinks its a personal choice thing, me I hate micro inverters and avoid them like the plague, but I work with people who like them, in the same office, go figure.

[Yaryman]

Solar Pete, bcroe, and samotlietuvis,

My point still is that without individual panel monitoring, the Sunpower warranty is virtually useless.

You represent the elite of the elite solar panel owners. You aren't the 1%, you are the .1%. ( congratulations )

How many owners can look at the temp and wind speed and determine what their output should be? ( Solar Pete )
How many owners have identical strings and take DC meter readings? ( bcroe )
How many owners check string Voltage and Current over time. ( samotlietuvis )

How would any of you three know which panel had gone bad?

Would you call your installer and say, well my production has dropped from 25.86 kWh to 25.50 kWh, could you come out and check all my Sunpower panels?
What would you say after the laughter on the other end of the phone call ended.

Here's the math on those numbers just using my panels. ( not sunpower )
18 280 watt panels producing 25.86 kWh. That's about my average for the last week on sunny days.
Suddenly one panel drops to 75%. So I now have 17 panels producing 1.44 kWh and one panel producing at 75% or 1.08 kWh for a grand total of 25.5 kWh.

I'm not pimping micro inverters or Solar Edge, just saying without one of those 2 systems its, VERY, VERY, VERY unlikely most people
that own Sunpower systems could or would EVER detect a single panel failure.