Mix And Match Solar Panels

bloodofheroes

Just wondering if these two panels will play well together in a parallel system. I am planning to do five of the 250w panels and one of the 330w. Advice?

littleharbor2

Different voltages wont play well. These are two very different panels, one being 60 cells and the other 72 cells. The amperages are closer together so they would series wire a little better though the lower amperage will dictate output. Neither option is optimum.

bloodofheroes

So are you saying to flat dont do it? What happens if I do?

Photowhit

I always thought that in series, it would just bring the voltage of the higher voltage panel down to the same as the lower voltage panel. But there is a discussion around here somewhere where (I think) @BB. said it would hunt more for the maximum power point.

I'm assuming you intend to use these with a MPPT type charge controller? The 5 are not a compatible voltage for charging through a PWM charge controller.

mike95490

The panels are not a match for parallel connection,  Your 330W panels will be pulled down to the voltage of the 250V panels.

In series, they are much more closely matched, and could work, if their voltage is below the controllers max input.

bloodofheroes

mike95490 said:

The panels are not a match for parallel connection,  Your 330W panels will be pulled down to the voltage of the 250V panels.

Not "330w panels." Only one 330w panel.

Horsefly

The general rule is that if you want dissimilar panels to work in parallel, their Vmp voltages need to be within about 5% of each other. Similarly, to run dissimilar panels in series you need their Imp currents to be within about 5%. 

In your case the voltages are too far apart to run them in parallel, almost 20%. The lower voltage panels will drag down the voltage of the higher voltage panel.

As @mike95490 said, running them in SERIES isn't quite within 5%, but would probably be OK. The current through the string would be limited by the current of the lower Imp panels (the Boviet), which would limit the Suniva panel to 8.3A instead of 8.8A  at Imp. This would make it a 311W panel instead of a 330W panel, but that isn't too bad.

softdown

My understanding is that the higher output panels will basically match the lower output panels when used together. I like to keep things simple. 

bloodofheroes

Horsefly said:

The general rule is that if you want dissimilar panels to work in parallel, their Vmp voltages need to be within about 5% of each other. Similarly, to run dissimilar panels in series you need their Imp currents to be within about 5%. 

In your case the voltages are too far apart to run them in parallel, almost 20%. The lower voltage panels will drag down the voltage of the higher voltage panel.

As @mike95490 said, running them in parallel isn't quite within 5%, but would probably be OK. The current through the string would be limited by the current of the lower Imp panels (the Boviet), which would limit the Suniva panel to 8.3A instead of 3.8A  at Imp. This would make it a 311W panel instead of a 330W panel, but that isn't too bad.

Thats kind of what I was wondering. Just dont want to do damage to the panel. I can live with it running at the current that the rest of them are running.

Estragon

As you may already know, you'll need to fuse/breaker each panel to avoid a short in one panel being fed by current from the other five.

Horsefly

Note that I was in too much of a hurry when I typed my reply above. I've fixed it, but the key thing is you can run your panels in SERIES, but I wouldn't run them in parallel.  Sorry for my error.

Do what I meant, not what I said.  

bloodofheroes

Estragon said:

As you may already know, you'll need to fuse/breaker each panel to avoid a short in one panel being fed by current from the other five.

What kind of fuses do you recommend?? Keep it cheap. Its a small system. I am just doing this for a R/V.

Photowhit

What kind type and kind of charge controller will you use? What system voltage will you use?

bloodofheroes

Photowhit said:

What kind type and kind of charge controller will you use? What system voltage will you use?

I dont have a charge controller. Its grid tied. I use more energy than the panels provide. The system is 24v

Estragon

> @bloodofheroes said:
> Estragon said:
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> As you may already know, you'll need to fuse/breaker each panel to avoid a short in one panel being fed by current from the other five.
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> What kind of fuses do you recommend?? Keep it cheap. Its a small system. I am just doing this for a R/V.

MNTS holders w/15a fuses, about $8ea for holder + fuse from our host. Personally, I'd use MNEPV breakers @~$11ea.