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Discussion Starter #1
Hi,
I have been doing my research and planning on a solar system on my T5. I have bought 1 x 100W panel and looking to get a MPPT Controller. The 100W panel has the following spec:

Related power:100W
Open circuit voltage (Voc):21.6V
Max power voltage (Vpm):17.3V
Short circuit current (Isc):6.17A
Working current (Iop):5.78A

I could get a 75/10 (75V 10Amp) controller and all would be well. But say I wanted to put another panel in later down the line and run 2 x 100W so 200W total.

If I wired the 2 in Parallel then it would be a potential current of 11.56 which would be more than the 10A Controller could handle.
But say I wired them in series then it would 34V and 5.78A so assuming the MPPT controller is capable of 35V (which it is as the one I am looking at will handle 75V) then the 10A controller would still be fine.

My question is would a 10A controller running 5.7A load be more efficient than a 15A controller running the same 5.7A load.
Would I be better off buying the 15A version for £1 more or stick with the 10A and mean I would have to run the second panel in parallel in the future?

Thanks
 

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Discussion Starter #3
Inverters run more efficiently when working near max...if I install a 3.8kw domestic system I use a 3.4kw inverter
I ran a house system with Enphase Micro inverters on every panel but with MPPT DC to DC Inverters for charging a 12V battery does the same principles apply?
 

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I think your theory is sound and remember the max output current is exactly that in ideal conditions.


One point to note though, as I have also pondered the idea of getting two 100w panels and putting in series to get the most out of the MPPT, is that if you park up where there is a bit of shade then the output of the total array is hit by one panel being shaded, whereas in parallel the unshaded panel can still deliver it's max output. Worth having a read about the pros and cons of series versus parallel.



I'm thinking I'll fit a single 200w or 250w panel now.
 
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