How many panels in a string

Jaboter · September 22, 2018, 3:50pm

Hi, how many solarpanels of 350 wp can I put in a string?

Marty · September 22, 2018, 10:34pm

Hi Jaboter, that depends in the inverter. What is the model of the inverter and what is the model of the panel?

Jaboter · September 23, 2018, 7:18am

Hi Marty,
The panels are 22 Eurener Turbo Plus Black 350 wp with a powerbox Solaredge P370 each.
The 2 head inverters Solaredge se 3500 hd Wave parallel connected.

Marty · September 23, 2018, 10:10pm

Hi Jaboter

There’s actually quite a lot of calculations and considerations that go into the design of a solar system. Where are you based? I would highly recommend getting the system properly designed before install, and in many countries that is a legal requirement. Systems designed poorly (or not at all), will underperform at best, and are dangerous at worst.

It’s been a few years since I have designed a system. From my loose calculations the max panels you would put on a string is 10. So, I would put 2 strings into each inverter, but how they are configured would depend on the system design. Again, I would say it’s well worth getting a designer involved in the install.

Cheers
Marty

Jaboter · September 24, 2018, 6:35am

Hi Marty,

I understand that it is very important to make a setup to avoid problems. Here’s the basic setup. I think this one is the best setup, also according to a specialized company.

Thanks for your response.

Regards,

Jack

Jack Botermans
Lieu-dit Brudieux

23460 Saint Martin Château

France

0033555647063

0031622559706

Marty · September 24, 2018, 9:07am

Hi Jack,

Ok so they are looking at 11 in a string. That’s probably fine, I guess on occasions when the voltage may be too high for the inverter it would just cap it at the max. I like the idea of oversizing the max output of panels to the inverter in general, I’m not sure exactly how that should be done in practice. The general principle being that the system will rarely, if ever, run at 100%, so better to oversize the inverter in order to get it running closer to max more often.

I guess the alternative is to parallel 2 x strings of 6, and 2 x strings of 5, but with the lower voltage I think the inverter would not be as efficient?

Would be interesting to hear from some experienced installers @BHekman @Svarky about this one, and their thoughts on oversizing the inverter.

Svarky · September 26, 2018, 1:53am

Hi Jaboter,

Are you working with a trained solaredge installer? If not you may void the warranty so be careful. I’m not sure what the regulations are in France though.
Depending on your local electrical regulations you can have 22 panels in a single string using the SE6000 or larger inverter. (or you can use 2 x SE3500). Why would you want to use 2 inverters?
With the solarEdge inverters you can oversize to 155% (if the local network allows this)

Hope this helps,
Jason

Svarky · September 26, 2018, 2:04am

Here is some basic design guidelines… SolarEdge also have some free online system design tools to verify the components will function together.

Jaboter · September 26, 2018, 5:55am

Hi Jason,

I’m using two inverters and two strings of 11 panels with a optimizer each.

Also I’m working now with a trained electrician who advised me the set up. In France it is very difficult to find one. Lots of idiots on the solarmarket here.

Thanks for the reaction.