question

Noisy Boysie avatar image
Noisy Boysie asked

SmartSolar-MPPT 2 string or 1 string

Hi

I have 2 diffrent angle panel strings becasue of my setup only 1 set can be angled at 35deg south facing and the other string only 12deg south facing. All panales are the same 1p5s 365w 40v VoC

My question is there any benerfit of 2 strings and there for using the RS 100 over 2s5p on a 250/60
There is no option to place them both at 35deg due to space.

Im in the uk hence the 35Deg optimum, the shed its on has a 12deg roof and not enough room to set them all to 35deg.

Obviously I could also go for twin 250/60 but being slightly more cost then the Rs100 it doesnt make sense to double up.

I'm making an assumption that the RS100 can take 450v on each tracker? as I coudlnt work this out based on the spec sheet. although possibly in the manual/setup if i looked harder

Regards

Boysie


Edit: I can also see that while the 250/60 have 4xMC4 connectors as it only has 1 tracker it only really assist in connecting higher AMPs parallel settings by deviding them across 2 input pairs and I dont think it would assit with 2 diffrent angle string albeit they are both same south facing. I'm also expecting the lower ones on the roof to suff shading issue during winter and want to avoind them dragging down the other string which should have this problem


MPPT Controllersmppt rs
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2 Answers
wkirby avatar image
wkirby answered ·

There is a small price difference between 2x 250/60 and a RS100, the latter being slightly more cost effective.
So, it could be worth experimenting with just 1x 250/60 and see how you get on. The caveat to just one is that the full potential of your array will not be realised as it will be limited to just over 3KW when the sun pops out to say hello. Here in sunny Norfolk I don't notice much difference in output between my 45°and 25° arrays in summer time, but much more in winter time. Also, the difference in array angles will not be very noticeable in cloudy weather but much more noticeable in sunny weather at winter time when your 12° array will be at a very shallow angle to the sun.

If you don't want to mess around experimenting, then I'd suggest the RS and take advantage of the two trackers and yield the full potential from each string during fine weather.

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Phil Gavin avatar image
Phil Gavin answered ·

It sounds like you satisfy these two conditions:

Condition 1: Both strings have the same number of the same type of panels.

Condition 2: All panels within a string are in the same direction at the same tilt. The strings themselves can be different tilts and directions.

I can basically guarantee with a single 260 60A MPPT you will still have headroom if you parallel those two strings. You will probably have enough headroom to consider a third-string (in a different direction) on that same MPPT.

Panels are relatively cheap, MPPT's are expensive, make an MPPT work a long day.

I deliberately do this with my arrays, it works best with an East and West array. I'd be looking to squeeze 4 strings onto an E-W array combination.

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