question

rayface avatar image
rayface asked

Wiring in series or parallel

Hi

Looking for some advice, am very new to solar!

Ive got 2 panels (340 Watt, VOC 41.55, Vmp 34.73)

The controller is the mppt 100/50

The battery is a renogy 100ah smart battery

Would I be best to wire these 2 panels in parallel or series ?

Sorry for the basic question! Any advice welcome regarding series and parallel pros and cons; wiring sizes etc appreciated. I'm a complete novice !

wiring
1 comment
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duswami avatar image duswami commented ·
I agree with @Seb71 , I would go up a size on your MPPT, while you probably wouldn't blow past 100v and you can experience some variation in panel efficiency and other factors it's def possible. I'd consider going 150/50 or a smidge higher on the AMPs and give yourself room for expansion. You could get 2 more panels in the future (same specs) and wire them 2s2p (series-parallel).

Make sure you also upside your wiring. Depending on the length of your wire run and considering voltage drop don't try and just barely size it. If you might expand also take sizing into consideration there as well.

My voltage range is near yours with potential of 119v taking temp into consideration. I have a 100ft run and am pushing around 38A. Just to be safe I went with 8 AWG to limit voltage drop. My drop is under 3%. Hope that helps!

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5 Answers
seb71 avatar image
seb71 answered ·

12V battery?

What's the coldest temperature you had at that location?

With the Voc of 41.55V, two in series probably will be OK for an 100/xx charger, but you MUST check this for the lowest temperature.


If that Voc<100V at lowest temperature criteria is met

and

both panels will be oriented the same

and

you do not have any shading issues

then

for sure go for series wiring of PV panels.


With PV wired in series you have higher voltage and lower current, which (in short) means more efficient.


Note:
If you didn't already bought the 100/50 MPPT, look into a 150/60 MPPT instead.

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rayface avatar image
rayface answered ·

Hi


Thanks for your input;

I should have mentioned that these will be mounted onto a campervan roof so at times they will be shaded , sometimes they won't. Both facing the same way (though as they will be mounted flat on the van, they won't be mounted at the perfect angle like the would on a south facing sloped roof for example)

There won't be any room for expansion after these two go in the roof. I did already get the 100/50 controller (hopefully this will be enough?)

The cable run will be reasonably short (at a rough guess I'd say around 10 foot.) We're mounting the panels and getting battery in place next week so will have a better idea of distance then.

We are in the UK so the outside temperature (hitting the panels) could get upto -10 degrees Celsius worst case scenario in winter.

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rayface avatar image
rayface answered ·

Ye it's a lithium 12volt renogy battery

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klim8skeptic avatar image
klim8skeptic answered ·

Flat on roof with possible shading, 12v battery, 100-50 mppt?

No brainer, 2 panels in parallel.

A suitable y connecter/cable to parallel the panels, and suitably current rated cables down to the mppt.

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rayface avatar image
rayface answered ·

Thanks , ye flat roof, possible shading, 100/50 mppt and a 12volt 100ah lithium battery.

I'll look into suitable cables next.

Would the Y connector (to parallel the 2 panels) be best on the outside (roof of the van) or on this inside.



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