Hello everybody. Newly-joined and delighted to be a member of the community. I am from Philippines. Currently, my set-up is a Growatt offgrid SPF 5000ES, 3- 2.56kw ARK L batteries and 10- panels (8- 325w & 2- 455w string in series). Installed for more than a year without any issues until just recently. The string was intentionally overdesigned as the azimuth and tilt (due to my roof orientation) are way, way far from ideal plus the year-round temperature in Philippines is relatively hot. Thus, expected that the panels would never see their STC-rated values. Total Voc of panels is 466v, and rated PV voltage input of inverter is only 450v. Until now, ONLY ONCE & only momentarily did the inverter trip, due to PV-in voltage is too high. Instead of doing modification on panels which are on the roof and not readily accessible, is there such a thing like DC voltage limiter (or the likes) that I could install upstream of the inverter so as the PV voltage output would just be limited to 450v and would eliminate the risk of frying the MPPT of my Growatt SPF inverter? Embarrased to ask such question, but better ask the and hear from experts… Merry Christmas to all, by the way.

Edited December 22, 20222 yr by RJogs

16 hours ago, RJogs said:

Hello everybody. Newly-joined and delighted to be a member of the community. I am from Philippines. Currently, my set-up is a Growatt offgrid SPF 5000ES, 3- 2.56kw ARK L batteries and 10- panels (8- 325w & 2- 455w string in series). Installed for more than a year without any issues until just recently. The string was intentionally overdesigned as the azimuth and tilt (due to my roof orientation) are way, way far from ideal plus the year-round temperature in Philippines is relatively hot. Thus, expected that the panels would never see their STC-rated values. Total Voc of panels is 466v, and rated PV voltage input of inverter is only 450v. Until now, ONLY ONCE & only momentarily did the inverter trip, due to PV-in voltage is too high. Instead of doing modification on panels which are on the roof and not readily accessible, is there such a thing like DC voltage limiter (or the likes) that I could install upstream of the inverter so as the PV voltage output would just be limited to 450v and would eliminate the risk of frying the MPPT of my Growatt SPF inverter? Embarrased to ask such question, but better ask the and hear from experts… Merry Christmas to all, by the way.

No unfortunately nothing that I know. Easy way out is to connect only 9 panels in series. Rather risk 325W less than a damaged inverter and no system while it is in for repair. 

7 hours ago, Scorp007 said:

No unfortunately nothing that I know. Easy way out is to connect only 9 panels in series. Rather risk 325W less than a damaged inverter and no system while it is in for repair. 

Thank you for the sound advice… I was trying my luck if there is such a thing available on the market… On the other hand, since I still have 2 pieces extra panels, I am now contemplating to plunge into major re-wiring, add the 2 panels and have them in parallel connection with 2 strings (6 panels/string).

6 hours ago, RJogs said:

Thank you for the sound advice… I was trying my luck if there is such a thing available on the market… On the other hand, since I still have 2 pieces extra panels, I am now contemplating to plunge into major re-wiring, add the 2 panels and have them in parallel connection with 2 strings (6 panels/string).

A wild guess would be that your 8 x 325w panels are throttling those 455W panels. If you can also try a different arrangement. Even if it means getting more 455w panels to use in a separate series string. 

 

Does the inverter have 2 x MPPTs? 

Edited December 24, 20222 yr by Scorp007

19 minutes ago, Scorp007 said:

A wild guess would be that your 8 x 325w panels are throttling those 455W panels. If you can also try a different arrangement. Even if it means getting more 455w panels to use in a separate series string. 

 

Does the inverter have 2 x MPPTs? 

Thanks for the comments. And yes, you are quite right. The 455w panels were later add-ons as my installer runs out of 325w panels… and we decided that it would be better to have the existing panels throttle the new ones rather than use/add new panels that will drag down the existing ones.

Unfortunately, my off-grid Growatt SPF-5000ES has only one MPPT. Yet, you injected an attractive idea of having add’l one string of all 455w panels… which may result to higher current input and would approach my inverter voltage limit SAFELY… time to start saving for those additional panels 😁.

29 minutes ago, RJogs said:

Thanks for the comments. And yes, you are quite right. The 455w panels were later add-ons as my installer runs out of 325w panels… and we decided that it would be better to have the existing panels throttle the new ones rather than use/add new panels that will drag down the existing ones.

Unfortunately, my off-grid Growatt SPF-5000ES has only one MPPT. Yet, you injected an attractive idea of having add’l one string of all 455w panels… which may result to higher current input and would approach my inverter voltage limit SAFELY… time to start saving for those additional panels 😁.

Even if the 2 strings used in parallel differ with say 10V it should provide a better yield than the current throttling. In any case try the 2 strings as close as you can. 

I have used a 200w and 480w in parallel where the voltage differed about 5V and it worked very well 

3 hours ago, Scorp007 said:

Even if the 2 strings used in parallel differ with say 10V it should provide a better yield than the current throttling. In any case try the 2 strings as close as you can. 

I have used a 200w and 480w in parallel where the voltage differed about 5V and it worked very well 

It is reassuring to hear that. And you nailed it, my quick estimate showed that the voltage difference is theoritically on the order of 6.7v only. Thank you👏.