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

[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?

[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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[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...

[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).

[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.

[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.]

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.

[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.]

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.

[Yaryman]

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

[J.P.M.]

What the story call "failure" ( and it was just one story that everybody seemed to quote ) was producing at less than full capacity.

Not referring to the normal reduction in generation that is normal. Just producing a little less than it should be.

I'll ask in this post also, how does one know a panel has failed in 5 years unless they have individual panel monitoring?

As Dan and Bruce suggest, either 2 inverters and/or a clamp meter. I've got an array w/ 2 strings and an inverter w/ 2 MPPT's. They usually read a few Watts different under full sun, one panel out and I'd probably have a clue. For the question of which panel in a string of 8 ? For my case - only - As (I think !) I've got a pretty good handle on panel temps., I'd start by measuring them and look for the hot/cold ones in the suspect string which, once on the roof, would take me about 3 min. but that's probably an unusual solution.

I appreciate your point. There are ways to approach the dilemma you describe, most more/less workable and effective. Many folks here get what you're writing. Many more don't, and perhaps more importantly, don't care for any number of reasons as evidenced by how many average homeowners keep track of array output.

[Yaryman]

I have 2 identical string inverters. All I need to do, is note power at a time there is no shade; they
should be very close to the same. If not I run out with a clamp on DC meter and determine which
is the weak string. Finding one, I check for a panel with lower voltage. I actually had to do this
to sort out some "bargain" panels. If I only had one inverter, I'd have to use the clamp on to
periodically compare strings. Bruce Roe

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.

monitor.jpg

[DanS26]

I have 2 identical string inverters. All I need to do, is note power at a time there is no shade; they
should be very close to the same. If not I run out with a clamp on DC meter and determine which
is the weak string. Finding one, I check for a panel with lower voltage. I actually had to do this
to sort out some "bargain" panels. If I only had one inverter, I'd have to use the clamp on to
periodically compare strings. Bruce Roe

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.

[bcroe]

how does one know a panel has failed in 5 years unless they have individual panel monitoring?

I have 2 identical string inverters. All I need to do, is note power at a time there is no shade; they
should be very close to the same. If not I run out with a clamp on DC meter and determine which
is the weak string. Finding one, I check for a panel with lower voltage. I actually had to do this
to sort out some "bargain" panels. If I only had one inverter, I'd have to use the clamp on to
periodically compare strings. Bruce Roe

[Yaryman]

Haven't seen it. All I know with some confidence of observation and conversation w/ HOA owners and a lot of walking around is that over 8 years of installs of what's up to something like 1,600 - 1, 880 panels, none have failed. Now, in all honesty, some of those ~ 1,700 panels have only been producing for a few weeks, so the statistic is not as dramatic as it may look. Still, the low probability of failure of a quality product, S.P. or most any other panel from a reputable mfg. seems more than anecdotal at this point.

What the story call "failure" ( and it was just one story that everybody seemed to quote ) was producing at less than full capacity.

Not referring to the normal reduction in generation that is normal. Just producing a little less than it should be.

I'll ask in this post also, how does one know a panel has failed in 5 years unless they have individual panel monitoring?