Long time listener, First time caller. 10 yr old Sunpower System, need opinions

[vikes98]

Bought this house 2 years ago. Came with a now 10 year old Sunpower system with 2 inverters and 42 panels.

The panels are also 62x32 230 Sunpower panels. 29 are on 4 strings to a 7000m (single azimuth, slightly wnw) and 13 are on a 3000m (8 on a sw different angle and 5 also sw but slightly larger angle)

The system was spec'd as 9660 Watts DC and 8598 Watts AC. I'm in So Cal, so trying to figure out what this should generate on average per year. Any help would greatly be appreciated. All areas get massive unshaded sun year round for 6+ hours per day solar average. If my math is correct 8598 / 1000 = 8.598 kWH * 6.6 solar average days * 365 = 20,712 kWH / solar year max.

Please someone let me know if that assumption of max annual result is accurate.

Now, the two inverters have a daily and lifetime kWH meter. The lifetime has total operational hours. So if I take the readings per hour I get something close to 3.153 kWh production lifetime. Granted those hours are any solar hour and not peak solar hours...

If I assume that the operational hours annually are 12, this gives me an average per day generation of about 37.83 kWh and a ballpark of over the 10 years of about 13094 kWH / year including the months of this year. So 13k / 20.7k gives me a solar efficiency of about 63% AC output. If my average is 13k and there is a drop off of say 2% per year, that means at install this system was producing 14k and now is probably only generating 11.8k or so and declining. So today efficiency might be closer to 57% of design max.

Again, not sure if this is accurate or not...

I had a tech come out and do a warranty review. He only went to the inverters, told me 2 of the 42 are not performing, can't be 29 on a string, has to be even... Seems plausible. So 2 of my 7 strings have extra panels. One string has a potential short, but he didn't know why... Never got on the roof, never measured anything from each panel... This bothered me.

He recommended I look into upgrading to Solar Edge with optimizers. Looking at them, that seems to make a lot of sense... Except... I still have 15 out of 25 years left on the warranty on the panels and I was told that adding the Solar Edge system would void my panel warranty.

I reached out to Sun power to get clarification, they pointed the finger at the now out of business dealer of 10 years ago for a bad install (the 2 panels not balanced) and can't even give me an answer as if the 2 Sun power inverters are still under warranty or expired.

To top it off, if any of the panels are under performing, failed etc. They have no replacements for 62x32 panels. Which is a problem...

Problem is, these were put in prior to code change, so no one can put anything more on the roof than I'm already generating in the same spots.

I've had multiple solar vendors out who want to just rip and replace at massive cost...

Looking for some advice.

Would I expect to see any significant improvement from the existing system by adding Solar Edge as a replacement for the existing string inverters that might fail some point in the near future?

Would it help me understand if any of the existing panels are at or below a performance point to warrant a replacement or prorated refund (if even possible with Sunpower)?

According to a Sunpower rep, he stated that these 10 year old panels are not compatible with Solar Edge, but not sure if that is fact or just FUD to try to keep me looking at Sunpower...

Lastly, since code changed, in order to add panels, I need to look at other parts of the roof, which there are a few options. So if I kept and converted the existing 230 watt panels to Solar Edge with optimizers would it also then be possible to add additional panels elsewhere to this system.

Thank you for your time, love the show!

[bcroe]

Your system will only approach maximum output when a clear sun is perfectly
aligned (perpendicular) to your panels. That will only be briefly each day, nothing
like 6.6 hours. In addition the sun crosses at different heights over seasons, so
only 2 days a year will be at the best elevation. Time to recalculate.

If you have no shade, optimizers will do nothing for you.

Just adding panels may not do much, peak power will just overload the inverters into
clipping. A more complex arrangement of multiple panel orientations may do better,
usually not possible on a roof.

The usual rule is panel strings of the same operating voltage may be paralleled,
this rule could be used to replace some failing panels. I just make sure each
string has about the same number of series cells, regardless of how they are
distributed over multiple panels. Panels in series should have about the same
operational current rating for best output. Bruce Roe

[peakbagger]

IMHO, you need to get educated to the point where you can wade through the BS and understand your system. Everyone you talk to wants to get their hands on your wallet and they are banking on your ignorance. Solar Power your Home for Dummies is a good start on your education, plenty of used copies available on the net. If you truly have full sun during peak hours no need for optimizers. Nothing wrong with string inverters especially if they are located in a conditioned space or a nice cool basement.

String configuration is panel and inverter specific and is dependent on location of the array. The panels put out different voltages in winter and summer, once you pick the extreme coldest and warmest temp, its not that hard to calculate the upper and lower voltage of each panel. Then its a case of getting the specs for the inverter and find the maximum and minimum input voltage of the inverter. From there you calculate how many panels you need to connect in series that fit within the inverter voltage range. It may be odd or even. Ideally you want to get it on the upper end of the range without exceeding it. You also need to determine if the inverter has multiple MPPT inputs. Ideally you assign one string per MPPT but if not than you parallel the strings that have similar sun exposure.

IMHO, most newer string inverters die for three reasons, the number one cause is line surges from the home or the utility. There should be a quality surge suppressor on the inverter AC side. I like the Midnight solar SPDs but whatever you get do not go cheap. Second is probably poor location, you want the inverter in a shaded cool and dry space with good airflow. There are generally cooling fans and possibly filters to be cleaned. These are electronic devices and if they are not cooled components "cook". Third cause is somewhat related to cause 2 which is overpaneling the inverter. What this does is run the inverter at close to maximum rating more of the time, this usually means its runs warm which reduces electronics life. The installers over panel as it saves them money and they figure they are long gone before the shortened equipment life becomes an issue. I have three small arrays with two older inverters including one really old one and I attribute its long life to being underpaneled and in a cool basement.

[J.P.M.]

Start by reading "Solar Power Your Home for Dummies". You need an education. Your solar ignorance is screwing you as much as the vendors who see the ignorance and want to take advantage of it.

Or, they're almost as ignorant and don't have a clue as to what to do.

After the read and primary education, and for your own baseline, run PVWatts for each orientation to get a rough estimate of annual output, probably +/- 10 % or so due to weather. Sum the outputs of each array orientation and hang onto the model's hourly output.

After 10 years, the system output will be ~ 5+ % or so lower than when new due to system aging. FWIW, 3 older S.P. arrays (one is 11 yrs. old, 28 ea. 240 W.) in my HOA seem to have deteriorated ~ 3-5 % or so, but that's almost impossible to field verify.

If you want a system check/troubleshoot/analysis, to find out if the inverters or panels or wiring or all/some of them are the culprit(s), it'll probably cost you a few bucks, but if you find someone reputable and qualified to do it and you pay for that service, you might - but no guarantee, have a shot at getting not B.S.'d and treated like a sales opportunity. If you do that, call S.P. and get (in writing) what they'll accept as a valid checking procedure that will not void their warranty.

Note that if there are failed or failing panels, the system can be rewired with fewer panels and still function. if all the panels are still fit for service and the problem is inverter in origin, you'll probably need some rewiring of the strings. Any failed panels and their lost production can still be warranty claimed.

10 yrs. ago the system probably cost something like $6.00/STC watt. Today, the same quality can be had for ~ half as much per STC watt. If it's going to cost you a lot of $$ to examine and then repair the system, depending on the repair cost, and your electrical usage, which might me a lot different (lower ?) than the prior owner (meaning a smaller system will be suitable), you might indeed consider replacing what's there with a smaller and less expensive per STC watt system. Something to think about, especially if the inverters are nearing the end of their service live or have failed. I'd still see if I could get a professional eval. of the system separate from some dork trying to simply sell more product.

But, to reiterate, get educated before you do anything else. Your ignorance is you worst enemy and, in several ways, the easiest one to deal with.

[jflorey2]

Bought this house 2 years ago. Came with a now 10 year old Sunpower system with 2 inverters and 42 panels.

The panels are also 62x32 230 Sunpower panels. 29 are on 4 strings to a 7000m (single azimuth, slightly wnw) and 13 are on a 3000m (8 on a sw different angle and 5 also sw but slightly larger angle) . . .

I had a tech come out and do a warranty review. He only went to the inverters, told me 2 of the 42 are not performing, can't be 29 on a string, has to be even... Seems plausible. So 2 of my 7 strings have extra panels. One string has a potential short, but he didn't know why... Never got on the roof, never measured anything from each panel... This bothered me.

Panel count doesn't have to be even - BUT each string has to have the same number of panels if they are commoned at the inverter. (If the inverter has separate MPPT channels then this doesn't apply)

He recommended I look into upgrading to Solar Edge with optimizers. Looking at them, that seems to make a lot of sense... Except... I still have 15 out of 25 years left on the warranty on the panels and I was told that adding the Solar Edge system would void my panel warranty.

Optimizers won't help unless there is shading.

Would I expect to see any significant improvement from the existing system by adding Solar Edge as a replacement for the existing string inverters that might fail some point in the near future?

No

[macaddict]

If you have no shade, optimizers will do nothing for you.

Optimizers would give you panel level performance information. If a panel stops working or degrades faster, you would know which one it is.

[J.P.M.]

Optimizers would give you panel level performance information. If a panel stops working or degrades faster, you would which one it is.

They have that ability but:

1.) How many folks monitor performance or even know that capability exists ? Some folks do, and many posters and readers of this forum do know, but I'd suggest that group's knowledge is not representative of that of the general public.

2.) Since panels themselves seem to not fail much, and as an opinion only from what I can gather from looking at the content of this forum, it seems to me that a disproportionate number of posts around here discussing problems of lost output or other malfunctions that seem to be associated with SolarEdge equipped arrays. Anyone else share that opinion ?

Maybe the cure for panel level monitoring using SolarEdge optimizers and other SolarEdge equipment is not the best way to deal with what may be the overplayed and overhyped need of panel level monitoring, with SolarEdge equipment actually creating or being part of the problem it's supposed to be good at detecting.

Put 1.) and 2.) above together, and a common or at least possible to perhaps likely scenario might be that an owner rarely or never looks at their monitoring (I'd bet about the same frequency as most folks look at their electric meter, never mind the discussion about how many even know what they're looking at). Then, one panel's output fails for some reason, but the shortfall in output is not noticed in increased electric bills because it's only, say, 5% - 10% of the array's output with the weather variability also and further serving to mask any reduction in output. In that (common ?) case, there is a small(er) probability of the problem being discovered any time soon.

On the other hand, if an entire array's output, or maybe half of it's output suddenly disappears as would happen with a string inverter if one panel died, my guess is the probability of the loss being noticed a lot quicker is greater.

IMO only, the cure of using more equipment with more parts to fail is worse than the overblown disease it claims to cure. KISS applies here.

[vikes98]

Apparently my spr-230-wth-u are positive ground and are incompatible with Solar Edge any way. So basically, I have a declining 10 year old system that loses 25%+ on hot days (over 95F) vs a 75F day in June. Granted these are just averages, but clearly heat seems to be a factor in the generated power loss.

I do read the inverters nearly daily, the main reason Solar Edge was attractive was the ability to monitor each panel... However, I'd be happy for any monitoring at this point vs having to physically go look at the inverters before sunset and compare to the power company numbers the day after.

So it appears I need to see if Sunpower will do anything with the warranty claim first. Could always add solar somewhere else on the roof to make up for the declining output, but any of these areas are not ideal for solar generation, whereas the existing positions are.

Not a simple decision. Leave it alone, continue to pay about $3k / year in energy costs, add solar, to offset this and overadd, which will have about a 6 year payback. Replace the inverters with something that at least has monitoring, so I can better understand the potential issues with existing system... Or rip and replace. Which ironically, both Sunpower dealers recommended when I inquired about warranty inspections.

Bottom line, is I'm 45+ days in to waiting for Sunpower to do something to explain to me their 12 year 90% output guarantee and the declining performance. So far, their warranty department and escalation seems to move at a snails pace. Started with an email that said they'd get back to me in 2 or 3 days, then 5 days later another emails saying they'd get back to me in another week.

So, either Sunpower's warranty escalation is too busy dealing with warranty claims, and/or its understaffed. Needless to say, this doesn't bode well for my opinion on Sunpower, but since I have them currently, the best course is to at least pursue that until they do something...

[macaddict]

They have that ability but:

1.) How many folks monitor performance or even know that capability exists ? Some folks do, and many posters and readers of this forum do know, but I'd suggest that group's knowledge is not representative of that of the general public.

2.) Since panels themselves seem to not fail much, and as an opinion only from what I can gather from looking at the content of this forum, it seems to me that a disproportionate number of posts around here discussing problems of lost output or other malfunctions that seem to be associated with SolarEdge equipped arrays. Anyone else share that opinion ?

Maybe the cure for panel level monitoring using SolarEdge optimizers and other SolarEdge equipment is not the best way to deal with what may be the overplayed and overhyped need of panel level monitoring, with SolarEdge equipment actually creating or being part of the problem it's supposed to be good at detecting.

Put 1.) and 2.) above together, and a common or at least possible to perhaps likely scenario might be that an owner rarely or never looks at their monitoring (I'd bet about the same frequency as most folks look at their electric meter, never mind the discussion about how many even know what they're looking at). Then, one panel's output fails for some reason, but the shortfall in output is not noticed in increased electric bills because it's only, say, 5% - 10% of the array's output with the weather variability also and further serving to mask any reduction in output. In that (common ?) case, there is a small(er) probability of the problem being discovered any time soon.

On the other hand, if an entire array's output, or maybe half of it's output suddenly disappears as would happen with a string inverter if one panel died, my guess is the probability of the loss being noticed a lot quicker is greater.

IMO only, the cure of using more equipment with more parts to fail is worse than the overblown disease it claims to cure. KISS applies here.

I agree that most people won't look at that information but I was just correcting what bcroe stated that "if you have shade, optimizers would do nothing..". Panel level monitoring is not nothing.

[J.P.M.]

I agree that most people won't look at that information but I was just correcting what bcroe stated that "if you have shade, optimizers would do nothing..". Panel level monitoring is not nothing.

It's not nothing, but it will only amount to something if a user knows what to do with it and then uses that knowledge to actually monitor system output to catch system anomalies. My guess is those two conditions won't happen most of the time for most users. To the degree my guesses reflects reality, the panel level monitoring has the capability to cause more lost output than it'll flag or avoid.

Also, my other point was that more complicated systems are inherently more prone to problems.

Furthermore, more expensive, more complicated and sensitive electronics in less accessible and relatively harsh environments like a roof don't seem to me to be a path to greater system reliability.

I'd also suggest your edit from Bruce's post may have taken what he wrote slightly out of context.

[bcroe]

Optimizers would give you panel level performance information. If a panel stops working
or degrades faster, you would know which one it is.

If you have shading, or golf balls flying over from across the street, optimizers might
be worthwhile for you. But after over 3 million panel operational hours here, I have seen
zero panel failures. I estimate optimizers would increase the array failure occurrences
by AT LEAST an order of magnitude, what do you use to find optimizer failures?

I have had a couple of questionable source panels defective at time of installation,
there was no trouble detecting these on a sunny day. Tracking the individual panel
down in this simple string system only took a few measurements, doable by anyone
with the most basic electrical troubleshooting skills. But I guess we have a generation
that just expects all answers to be presented on a screen, with no way but pure faith
to verify the answer.

Have not heard from the OP again, since a single post 6 June. Bruce Roe

[J.P.M.]

Apparently my spr-230-wth-u are positive ground and are incompatible with Solar Edge any way. So basically, I have a declining 10 year old system that loses 25%+ on hot days (over 95F) vs a 75F day in June. Granted these are just averages, but clearly heat seems to be a factor in the generated power loss.

I do read the inverters nearly daily, the main reason Solar Edge was attractive was the ability to monitor each panel... However, I'd be happy for any monitoring at this point vs having to physically go look at the inverters before sunset and compare to the power company numbers the day after.

So it appears I need to see if Sunpower will do anything with the warranty claim first. Could always add solar somewhere else on the roof to make up for the declining output, but any of these areas are not ideal for solar generation, whereas the existing positions are.

Not a simple decision. Leave it alone, continue to pay about $3k / year in energy costs, add solar, to offset this and overadd, which will have about a 6 year payback. Replace the inverters with something that at least has monitoring, so I can better understand the potential issues with existing system... Or rip and replace. Which ironically, both Sunpower dealers recommended when I inquired about warranty inspections.

Bottom line, is I'm 45+ days in to waiting for Sunpower to do something to explain to me their 12 year 90% output guarantee and the declining performance. So far, their warranty department and escalation seems to move at a snails pace. Started with an email that said they'd get back to me in 2 or 3 days, then 5 days later another emails saying they'd get back to me in another week.

So, either Sunpower's warranty escalation is too busy dealing with warranty claims, and/or its understaffed. Needless to say, this doesn't bode well for my opinion on Sunpower, but since I have them currently, the best course is to at least pursue that until they do something...

I've had my S.P. system for ~ 6 1/2 years. It was well and professionally installed, and in that time, to the best of my knowledge, memory or recorded data, it has not hiccupped or lost output, and as best as I can determine has met all that was claimed for it and more.

However, I cannot say the same for the S.P. support. I stopped being hopeful of any professionalism from them after a few attempts early on at getting answers to questions relating to monitoring anomalies/data dropouts. Their support basically sucks. The folks on the other end are mostly ignorant of what they're doing, and aside from that, it doesn't help the communication that english seems to be a second language for most of them. They do not return calls or emails in a timely manner, if at all. When they did, usually after my persistent squeaky wheel routine, the information puked back was no more than a rereading of the hype and blather/B.S. that's about 90 % of their published information and nothing new or useful, or nothing I couldn't or hadn't already read for myself.

As for a warranty claim, you may have some luck. But, since any performance claim may need to have irradiance input to estimate any output shortfall caused by equipment problems, and since you probably don't have any way to provide that data, be prepared for some blowback.

[vikes98]

Have not heard from the OP again, since a single post 6 June. Bruce Roe

Not sure your math, but I just posted in #8. Not sure what that has to do with the discussion. I'm waiting to hear from Sunpower on even getting someone competent to measure the strings and verify the system's operational status. This has been the slowest experience I've experienced in awhile from any company. I started my inquiry with Sunpower 45 days ago and still have yet to have anyone actually look at a single panel. I'm seeing some significant dropoff in power generation, and I am concerned things are going south fairly quickly and trying to determine if anything is actually covered under warranty (appears highly unlikely at this point) and if not, what my best options are to upgrade, add or replace what I have.

Every dealer I've talked to just wants to rip and replace. Since the panels are in ideal solar generation unshaded locations, but in order to add or even upgrade existing panels, due to code and setbacks, permitting, etc. I'd have to add less or find more roof space, which is less than ideal.

[J.P.M.]

Not sure your math, but I just posted in #8. Not sure what that has to do with the discussion. I'm waiting to hear from Sunpower on even getting someone competent to measure the strings and verify the system's operational status. This has been the slowest experience I've experienced in awhile from any company. I started my inquiry with Sunpower 45 days ago and still have yet to have anyone actually look at a single panel. I'm seeing some significant dropoff in power generation, and I am concerned things are going south fairly quickly and trying to determine if anything is actually covered under warranty (appears highly unlikely at this point) and if not, what my best options are to upgrade, add or replace what I have.

Every dealer I've talked to just wants to rip and replace. Since the panels are in ideal solar generation unshaded locations, but in order to add or even upgrade existing panels, due to code and setbacks, permitting, etc. I'd have to add less or find more roof space, which is less than ideal.

Just sayin' here, but you may be stuck between a rock and a hard place. Either wait for S.P. to respond with some as yet unknown solution, or pay for a professional, knowledgeable and unbiased analysis from someone with no skin in the game, which is probably more than a little oxymoronic.

FWIW, I'd keep after S.P. Nothing can replace persistence. Even though they suck at customer service, leave them out of the loop and get the perceived problems fixed, or even touched without their input and imprimatur and you'll hand them the opportunity to void any warranty claims that may otherwise stick.

Not kicking you as you're blameless in vendor selection here, but potential PV users might take a lesson from your experience and predicament and be a bit more mindful of taking a longer view and spending a bit more time on vendor selection and maybe a bit less time and effort on finding the lowest initial price when considering all the details that go into acquiring a PV system.

[bcroe]

Not sure your math, but I just posted in #8. Not sure what that has to do with the discussion. I'm waiting to hear from Sunpower on even getting someone competent to measure the strings and verify the system's operational status. This has been the slowest experience I've experienced in awhile from any company. I started my inquiry with Sunpower 45 days ago and still have yet to have anyone actually look at a single panel. I'm seeing some significant dropoff in power generation, and I am concerned things are going south fairly quickly and trying to determine if anything is actually covered under warranty (appears highly unlikely at this point) and if not, what my best options are to upgrade, add or replace what I have.

Every dealer I've talked to just wants to rip and replace. Since the panels are in ideal solar generation unshaded locations, but in order to add or even upgrade existing panels, due to code and setbacks, permitting, etc. I'd have to add less or find more roof space, which is less than ideal.

Guess our posts passed in the mail. You did not address any of my technical comments
here. My opinion is simply check your peak power on a sunny day, and see if is consistent
with the rating of the inverter and panel rating at your tilt angle. Since you have somewhat
off south orientation, pick an optimum time of each orientation and check output of that
section. If the power is not available from your equipment, get a DC clamp on meter, a
great tool here.

Of course the dealers want to sell new stuff, the more expensive, the better. I suggest
getting the most out of your current investment, repaired if necessary. So find out
exactly if each component is delivering as expected. Knee jerk actions before finding
out exactly the facts will be costly and perhaps very disappointing.

As for annual energy collection, there are simulations that will take all your factors
including weather and make a decent estimate. This is a far better estimate than in
your original post, but still subject to weather variations in the second decimal place.
good luck, Bruce Roe