Replace a positive ground, Sunpower SPR-7000 to a transformer-less inverter

[danno1]

Hi Folks,
I have a 8.2Kw Sunpower system with 36 panels, (4 x 9) and 1 Sunpower SPR-7000 inverter w/transformer. Installed in 2009, my inverter has died with a Disturbance IMAX error. Sunpower has been useless in helping me or one of their own Sunpower distributors with finding a replacement - it died 5 months after the warrranty expired! Apparently there is no replacement plan for these old inverters with transformers. Now that they are failing - what do you do?

QUESTION: How do I go to a transformer-less string inverter like a Sunny Boy 7.0 (https://www.solar-electric.com/sma-s...-inverter.html) from my positive ground, inverter with transformer? Do I need to retrofit fit with a combiner box? Sunpower said the positive grounding ruled out a switch to this type of inverter.. Any help here is appreciated. Systems been dead for 6 months.
I'm not an electrician.... just need to understand the basics of what can or can't be done. There is a LOT of knowledge on this Forum...this has likely been seen before. I'm hoping there is a reasonable solution.
Thanks all,
Dan

[edustys]

Hi Fellow SunPower Owners,
I would appear that SunPower has left those of us whose Positive Ground Inverters has failed in a lurch. The interior of one of my my 13 yr. old. SPR-4000m Inverters has electrical scorch marks so, obviously, something went very wrong. Dealing with SunPower has been extremely frustrating. How does a company that warrantees solar modules for 25 years not have a plan in place to support Inverters which are warrantied for only 10 years when they fail?

I understand that technology changes rapidly but for those of us who bought into solar power in its adolescence and basically funded the advancements via our purchases of said solar systems, to be told that there are NO REPLACEMENTS and that NOTHING can be done, is simply unacceptable. These issues cannot come as a surprise. The only surprise is that replacement inverters and/or work arounds have not been put in place to support its loyal initial customers.

In the auto industry when OEM parts become scarce there has always been some enterprising manufacturer(s) who have come to the rescue. It would appear that is not the case in the Solar Energy industry unless I just haven’t looked hard enough.

If there are viable replacements or work arounds that you know of, please share that information with us. We would be eternally grateful.

[Keyboard Farmer]

I was able to replace my failed Sunpower inverter by buying a refurbished unit from youlovesolar.com They offer a variety of Sunny Boy inverters which are the same as the Sunpower units. SMA actually made the Sunny Boy as a private label for Sun Power. The Sunny Boy 6000 which I bought when delivered was actually a rebuilt Sunpower 6000 unit. My original failed unit was manufactured in 2009 and the refirbished unit was originally manufactured in 2014. Thus far the replacement has been working just fine. I paid $2,547 in November 2021for the refurbished inverter. Shipping to NJ from California was included. In my conversations with youlovesolar I was told that they employ a technician who was previously employed by SMA with over 30 years experience to do their refirbishment work. I still have my old unit which failed with the I Max Disturbance failure. I'd be willing to send it out for refirb if that would help anyone. I noticed checking now on the youlovesolar web site that they list many of the Sunny Boy units as wait listed. Hope this is some help.

[edustys]

I was able to replace my failed Sunpower inverter by buying a refurbished unit from youlovesolar.com They offer a variety of Sunny Boy inverters which are the same as the Sunpower units. SMA actually made the Sunny Boy as a private label for Sun Power. The Sunny Boy 6000 which I bought when delivered was actually a rebuilt Sunpower 6000 unit. My original failed unit was manufactured in 2009 and the refirbished unit was originally manufactured in 2014. Thus far the replacement has been working just fine. I paid $2,547 in November 2021for the refurbished inverter. Shipping to NJ from California was included. In my conversations with youlovesolar I was told that they employ a technician who was previously employed by SMA with over 30 years experience to do their refirbishment work. I still have my old unit which failed with the I Max Disturbance failure. I'd be willing to send it out for refirb if that would help anyone. I noticed checking now on the youlovesolar web site that they list many of the Sunny Boy units as wait listed. Hope this is some help.

Thank you so much for your recommendation. Through them I was able to find a replacement for my SunPower SPR-4000m “fried” inverter with a Sunny Boy SB-4000US inverter. The difficulty was compounded by the fact that our particular system is Positive Ground which is no longer the industry standard making it even harder to find replacements. It was also quite disappointing that the local installers or SunPower were not more forthcoming with information. I have a lot more respect for a company that stands behind their products and tells you what they will do rather than what they won’t do.

[Joseph.Unden]

My Sunpower SPR-7000, installed in 2010 along with 4 strings of 10 panels (8400 watts) seems to work fine except in the middle of the day, when the panels are producing around 6000 watts. At that point the inverter seems to be overloaded. It makes pulsating-buzzing noises and the reading jumps from around 6000 to around 3000 and back up ... every second or so. This is a problem which has developed over time. I have not gotten any error messages.

Has this happened to anyone else? This is the positive ground type of unit. I know that SMA made this unit for Sunpower and still makes SMA-7000 inverters. Are you guys saying the new SMA-7000 inverters are all negative ground?

[Keyboard Farmer]

Thank you so much for your recommendation. Through them I was able to find a replacement for my SunPower SPR-4000m “fried” inverter with a Sunny Boy SB-4000US inverter. The difficulty was compounded by the fact that our particular system is Positive Ground which is no longer the industry standard making it even harder to find replacements. It was also quite disappointing that the local installers or SunPower were not more forthcoming with information. I have a lot more respect for a company that stands behind their products and tells you what they will do rather than what they won’t do.

Glad you were able to find a solution. I was out of service for six months. SunPower Corporate was of no help because I owned my equipment. If it was a lease, they would have found a way to get me up and running to keep their monthly income. Very frustrating considering I paid $54,000 (before tax incentives) when the system was new. The SunPower tech who came out was sympathetic to my situation. He got the company to pay for a days work on my roof cleaning up squirrel damage, which I appreciated, but didn’t fix the issue. He also found a couple used inverters that we tried (they didn’t work) before we located the refurbished inverter from youlovesolar.com. It is amazing that SunPower has taken this position of not caring about the positive ground early adopters that basically put them in business. Imagine if Tesla did that to the original high dollar Roadster customers. The people who gave the company a large amount of their startup capital. I imagine the various state energy incentive programs wouldn’t be happy to know that their incentives to get solar power installed was being squandered because SunPower won’t support their products.

[edustys]

Glad you were able to find a solution. I was out of service for six months. SunPower Corporate was of no help because I owned my equipment. If it was a lease, they would have found a way to get me up and running to keep their monthly income. Very frustrating considering I paid $54,000 (before tax incentives) when the system was new. The SunPower tech who came out was sympathetic to my situation. He got the company to pay for a days work on my roof cleaning up squirrel damage, which I appreciated, but didn’t fix the issue. He also found a couple used inverters that we tried (they didn’t work) before we located the refurbished inverter from youlovesolar.com. It is amazing that SunPower has taken this position of not caring about the positive ground early adopters that basically put them in business. Imagine if Tesla did that to the original high dollar Roadster customers. The people who gave the company a large amount of their startup capital. I imagine the various state energy incentive programs wouldn’t be happy to know that their incentives to get solar power installed was being squandered because SunPower won’t support their products.

My original installer, who is no longer affiliated with SunPower nor in the area, stepped up to the plate and hired a local solar and electric company to install the 2 new old inverters. I decided to replace both 14 year old 4000 inverters at the same time and keep the still operational one as a backup. I used the phrase “new old” to describe this equipment which was manufactured in 2012 but still in the original factory sealed boxes as opposed to refurbished which may have been reconditioned after use or testing. That’s not to say that wouldn’t have bought refurbished but since they were the same price, $2,195 each, I went for the never used. The installation was completed two days ago and the system is humming along at full capacity once again.

SunPower is no longer the company it once was as I suspect the original founders are long gone and may have sold the company along with its name and established goodwill. Sadly, the newer regime did not value, as you stated so eloquently, “the positive ground early adopters that basically put them in business.”

For anyone looking for possible SunPower positive ground replacement inverters, check out the Sunny Boy products at youlovesolar.com. You Love Solar is a division of Solar CowboyZ but don’t let the name fool you, they are very professional and knowledgeable. Substitute the SPR prefix with SB and your inverter number followed by US (change SPR-4000m to SB-4000US) and you may just find what you’re looking for. Good Luck!

Thanks again Keyboard Farmer for taking the time to discuss your situation and solution on this forum. Without your assistance I’d still be scouring the internet looking for replacements instead of enjoying a functioning system.

[edustys]

My Sunpower SPR-7000, installed in 2010 along with 4 strings of 10 panels (8400 watts) seems to work fine except in the middle of the day, when the panels are producing around 6000 watts. At that point the inverter seems to be overloaded. It makes pulsating-buzzing noises and the reading jumps from around 6000 to around 3000 and back up ... every second or so. This is a problem which has developed over time. I have not gotten any error messages.

Has this happened to anyone else? This is the positive ground type of unit. I know that SMA made this unit for Sunpower and still makes SMA-7000 inverters. Are you guys saying the new SMA-7000 inverters are all negative ground?

Good afternoon Joseph:

SMA inverters manufactured before 2012 were warrantied for only 10 years as I sadly found out when 1 of my 2 2008 SPR-4000 positive ground inverters failed. I wish I was able to upload the picture of the inside of the failed inverter but apparently it was too large or I just didn’t know how to do it properly so I’ll attempt to describe it instead. The middle-left side of the inverter had electrical soot and scarring, the type you’d find when a there was a short in wiring at an outlet, next to the motherboard which is located in the middle-right in the unit. We never got an error code, just an unexpected decline in production in some months when, historically, there should have been significantly more.

I called my original installer in September of 2019 who, it turned out, was no longer affiliated with SunPower, citing that my production seemed to be waneing and that upon cleaning the panels we found 2 that had some minor damage. After reviewing the photos I supplied, they determined that the damage would not have affected the panels production and cancelled the physical inspection. Knowing how extreme heat can affect solar production, I felt my concerns were unfounded as the fires had shrouded the sun for nearly a month or two and that that was most probably the reason for the decline. Then came Covid and, frankly, I put my solar concerns on the back burner until the arrival of my January PG&E statement which showed that the system has only produced 21.1 kWh as opposed to a historical 3-year average of 215 kWh for that same time period. February production came in at only 33.8 kWh as opposed to a norm of 281 kWh so there was obviously an issue. The inverter never had an error code.

Backing up a little here to October, 2021, when I was contemplating adding additional panels to take care of my yearly true-up, I had a site inspection done by another Solar dealer, SunRun, which I later decided not to peruse. In November, 2021, however, still having concerns about panel damage and the historic drop in production by about 20%, I was able to find another authorized SunPower dealer and had them come out for an inspection. The technician inspected the panels, ran voltage checks and whatever else they do and stated that there were no error codes and that the damage had not breached the system which appeared to be working fine.

Naturally, when the PG&E (Pacific Gas & Electric) statement for December generation showed otherwise, the SunPower dealer was summoned once again and this time he encountered a blank, black screen on 1 of the inverters and upon opening it up, found the scorched contents. Then began my search for a replacement which was further complicated by the fact that my system, like yours, was “positive ground.”

As I found out luckily from this very forum was that the SunPower inverters were manufactured by SMA. SMA manufactured Sunny Boy inverters that are not only compatible but, in most cases, are the identical ones used by SunPower. In my case, I was able to find 2 SB-4000US positive ground inverters which I just had replaced 2 days ago, keeping the working inverter as a spare. The system is working perfectly.

Incidentally, even though my original installer is no longer SunPower they did step up to the plate and hired a local solar and electric company to do the work as the other authorized dealer who did the 2 inspections, at $385 a pop I might add, declined the work starting unfamiliarity with “positive ground” equipment and liability issues. I also found that the current SunPower was not very supportive of its previous “positive ground” customers and their equipment issues. The best information was located right here in this site.

So, very log story short, check out youlovesolar.com to see if they have any SB-7000US inverters in stock. Honestly Joseph, it’s not a matter of if but when your inverter fails and it will save you tons of grief knowing where to go to find what you need. I hope this has helped and I wish you Luck!

[Joseph.Unden]

Wow. Sounds like I am heading in the same direction you went. Thanks for telling me your story. I have a bunch of questions I hope you will answer ... like:

Were the inverters you found refurbished like the post above us?

Did you check into micro inverters?

Does anyone make positive ground microinverters?

Why do you have 2 inverters instead of one?

How did you find the Sunpower dealer to help you (my installer is no longer in business either)?

It is hard to believe someone doesn't make the positive ground inverters to service all of us with the older panels whose inverters are starting to wear out.

Thanks again for your help. I have emailed youlovesolar and hope to hear from them tomorrow (today is Sunday).

[edustys]

Wow. Sounds like I am heading in the same direction you went. Thanks for telling me your story. I have a bunch of questions I hope you will answer ... like:

Were the inverters you found refurbished like the post above us?

Did you check into micro inverters?

Does anyone make positive ground microinverters?

Why do you have 2 inverters instead of one?

How did you find the Sunpower dealer to help you (my installer is no longer in business either)?

It is hard to believe someone doesn't make the positive ground inverters to service all of us with the older panels whose inverters are starting to wear out.

Thanks again for your help. I have emailed youlovesolar and hope to hear from them tomorrow (today is Sunday).

Hi Joseph,

My inverters were “new old stock” meaning that while they were manufactured in 2012 they were still factory sealed in their original boxes and have never been used. YouLoveSolar (a division of Solar CowboyZ) also had refurbished ones but since they were the same price ($2195 each + tax + shipping) I went for the New Old Stock.

My system was installed in June of 2008 and, as far as I know, microinverters were not something that was widely available or advocated at the time. Because, like yours, my inverters are positive ground, I don’t know if there is any compatibility there but certainly do your own research to get the complete picture if that’s the way you might want to go.

My system has 44 panels divided by 2, half (22) on the south side and the half (22) on the west side of the roof. My panels are SPR-210’s which may have had something to do with the decision on the part of the dealer to go with 2 inverters SPR-4000 inverters. Efficiency and/or longevity perhaps, your guess is as good as mine.

After I was told that my original installer was no longer affiliated with SunPower I felt I had no other recourse than to reach out to SunPower directly. My conversation with SunPower was hopeful but, as it turned out, lacked any meaningful follow thru other than names of possible dealers who may still possess new old or refurbished stock. I went on the SunPower website and inquired about local dealers and came up with a list. Based on the list I looked for customer reviews and picked, who I thought, was a company I could work with. In the end, after 2 inspections at $385 a pop, I was disappointed to be told that they would not be in a position to install the replacements I found due to their unfamiliarity with positive ground equipment and that they felt that lack of knowledge could have liability issues for their crew. Perhaps they should have said something about their reluctance to work on positive ground equipment before they sent the technician out the second time so I could have saved some money. Ask the question before anyone comes out because no one comes out for free. I, fortunately, kept the cell phone number of our original salesman who miraculously still had the number and who, though out of the business since 2010, still had contact with some of his original crew who have gone on to bigger and better things in the industry. We always felt he was an honest man and, to his credit, he did not disappoint. His contact validated the compatibility of the Sunny Boy inverters. Told me to substitute SB for SPR (SB-4000US replaces SPR-4000m) and once that window opened, I was able to ask for what I needed. Being armed with some of the vocabulary used within an industry can be most helpful when asking questions and getting answers so the more you learn the better you will understand.

I completely agree that those of us who were early into solar energy and ostensibly funded the subsequent advances into that industry, have been left behind by that same industry to fend for ourselves to keep our systems running long enough to recoup our investments. I suppose it’s no different than the evolution of the smartphone from the flip phone albeit the amount invested vs. the return on a phone is far less than in purchasing a solar energy system. Much like new technology in any field, eventually support, or in this case the manufacture of replacement parts, if not taken up by an after-market entity, ceases and the only alternative is to get rid of it or replace it with something newer. Well that day isn’t here yet if you know where to look and who to ask.

Best of luck to you Joseph and keep us apprised of your journey to full operation.

[Joseph.Unden]

Thanks edustys! Got my hopes that you love solar can help me. I'll let you know how it all turns out.

[Joseph.Unden]

I am learning a lot! First off, it doesn't appear anyone makes any inverters for our positive ground panels. I contacted YOULOVESOLAR and they had a "Certified Used" SMA 7000US one for sale ($2300 + tax & shipping). I bought it figuring that might be my only chance of saving my system (panels). Since I ordered it I have contacted a tech at SMA USA and he said the most likely cause of my inverter fluctuations during high production times was old age. He suggested I reduce the number of solar panels feeding into the inverter. That got me to thinking, maybe I should use both my current inverter (which seems to work well if under 5000 watts) and the "Certified Used" inverter and feed two strings into each. The SMA guy is going to check the specs to see if that is possible.

Since you are using 2 inverters, I thought I'd ask how you wire them. Do you just take the feeds out of both and combine them in the AC shut-off box? Or is it more complicated than that?

Thanks for your help!

[DanS26]

The Fronius IG transformer based inverters can be field adjustable for either positive or negative ground. In fact Fronius branded Sunpower inverters do the same. Search the internet for these older transformer based inverters. If you find one, buy it.....they are bullet proof.

Good luck........


Look here........

https://www.ebay.com/itm/224373592279?hash=item343db550d7:g:3GoAAOSwUNZgQOgv#shpCntId

[oregon_phil]

I am learning a lot! First off, it doesn't appear anyone makes any inverters for our positive ground panels. I contacted YOULOVESOLAR and they had a "Certified Used" SMA 7000US one for sale ($2300 + tax & shipping). I bought it figuring that might be my only chance of saving my system (panels). Since I ordered it I have contacted a tech at SMA USA and he said the most likely cause of my inverter fluctuations during high production times was old age. He suggested I reduce the number of solar panels feeding into the inverter. That got me to thinking, maybe I should use both my current inverter (which seems to work well if under 5000 watts) and the "Certified Used" inverter and feed two strings into each. The SMA guy is going to check the specs to see if that is possible.

Since you are using 2 inverters, I thought I'd ask how you wire them. Do you just take the feeds out of both and combine them in the AC shut-off box? Or is it more complicated than that?

Thanks for your help!

Original Inverter with middle of the day power fluctuations from 6000 watts to 3000 watts every second or so:

Did SMA service do any other troubleshooting besides suggesting the problem was just old age? It probably is old age, but troubleshooting should be more like an interrogation rather than a simple answer.

SMA suggested reducing the number of solar panels to help solve your problem. Less DC power into the inverter, inverter components might run cooler, therefore the inverter might function properly.

I don't recall where you live or where your inverter is mounted. Is your inverter mounted outside in the sun at miday?

Your inverter has cooling fans. Do your fans actually work? Have you ever cleaned the fans/intake area per maintenance described in the manual? You can also check fan functionality by forcing the fans on by setting a jumper or by setting a fan test parameter to on/1.

Lack of a hard fault might not mean derating isn't happening. Did you check the log file? I assume you have installers access. During the "fluctuation event", you can log onto the installers screen and check operation status to see if derating is happening. Also, you can check your DC and AC screens to see if anything unusual is happening.

New inverter:

Your power company thinks you have one 7000 watt inverter with about 30 to 32 amps max going back onto the grid. If you hook up another 7000 watt inverter, your have to treat this as if 60 to 64 amps are going back onto the grid. Nothing in your solar AC circuit and/or electrical panel is set up to handle this.

You bought your new inverter to be a replacement/spare. Even if the SMA guy says that connecting two inverters in parallel will work in theory, that doesn't mean it's safe or doesn't violate your city/county electrical codes.

[Joseph.Unden]

oregon_phil,

Thanks for your insightful comments. You obviously have worked with solar systems.

SMA says this about derating ...

Temperature derating occurs for various reasons, including the following:

• The inverter cannot dissipate heat due to unfavorable installation conditions.
• The inverter is operated in direct sunlight or at high ambient temperatures that prevent adequate heat dissipation.
• The PV array and inverter are mismatched (power of the PV array compared to the power of the inverter).
• If the installation site of the inverter is at an unfavorable altitude (e.g. altitudes in the range of the maximum operating altitude or above Mean Sea Level, see Section "Technical Data" in the inverter operating manual). As a result, temperature derating is more likely to occur since the air is less dense at high altitudes and thus less able to cool the components.
• A constantly high DC voltage (V_MPP) is present at the inverter.

I don't think any of these apply to my situation.

I live in Southern California (altitude approx 400 feet) and my inverter has been located in my garage since installed in 2009. The temperature in the garage is never excessive, especially now during the winter. The inverter is derating as we speak and the temperature in my garage is 65 degrees Fahrenheit.

I have removed and cleaned the fans. I have used the jumpers to do the fan test and have observed the fans blowing while the unit is derating.

My panels are producing about 430 DC volts, well within the range listed in the specs (250-600 V DC)

My panels produce approximately 8400 watts (40 panels at 210 w each). The Inverter specs list the max array input power at 8500 watts.

I am not an installer. I have quite a bit of experience (built and wired my own house and other structures) and like to research projects, but do not claim to be a solar professional. I will look into trying to access the log or find someone who does.

Since the my last post the SMA tech has gotten back to me and recommended using the "new" inverter (not two inverters). But I would still like to know how edustys! uses two inverters.

Thanks again,