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nick5000 avatar image
nick5000 asked

Easysolar II 48/3000 or Multi RS Solar 48/6000 for 3 or 4 550W panels

I’m planning the installation of 3 or 4 550W (42V, 13A) solar panels on my boat and am thinking about the controllers and inverter options.

I like that the multi RS is smaller and lighter with a bigger inverter, while the easysolar is more flexible with panels (accepting lover voltage).

I’m planning to use these panels, SKT550M10.

https://www.enfsolar.com/pv/panel-datasheet/crystalline/48941

If I put 3 42V panels on an arch on the boat, they should produce 126V in series connection, however I’m not sure how often they might produce less than 120V that’s required for the Multi RS to start. If partial shaded, or low light condition is it likely that the output will be less than 120V and I won’t get any charge at all? If I can fit 4 panels then I assume less of an issue.

Alternatively I could use the EasySolar-II 3kVA MPPT 250/70 GX and connect 2 paralleled panels in series (if using 4 panels), or 3 in series with 3 panels, however with no risk of not getting to the 120V startup voltage.

I don’t think I’d need the other features of the Easysolar, as this will be a very simple setup.

Thanks!

EasySolar All-in-OneMulti RS
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Alexandra avatar image
Alexandra answered ·

@nick5000

Of you don't need the 6kVa for head room then the 3kVa would be better in some ways.

You are right the weight is attractive and the easy progamming. The battery bank is the other consideration. What batteries are you planning on using though? 3kVa needs half of what the 6kVa needs.

The RS MPPT needs 120v to start but will track down to 80V. The panels you are looking at has a vmpp of 41.96v I think that what you based your calcs on. The VOC is just over 49.45v. I still agree 4 panels would be better. But 3 would still work.

At the end of the day it is a solar system, so really the solar being the main point, needs to be optimized as much as possible.

I guess this is an answer that is not really an answer. It is up to you at the end of the day as you have to live with it.

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nick5000 avatar image nick5000 commented ·

Thanks, so I should look at the VOC of 49.45V to determine if it would reach the startup voltage of 120V? I'd assume the voltage in the morning, or if partially shaded will be lower? I could probably connect a 4th panel but it could be less optimally placed and could get some more shade at times, which I understand could make the whole series array worse off compared to just having 3 panels with sun.

Would 3 panels mvpp 41.96V / VOC49.45V still be able to startup the Multi RS in most conditions?

I'm planning 200aH 48V battery. The 6kVa would be just for the flexibility of being able to run several equipment at the same time for short periods, I wouldn't need it for extended time.
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nesswill avatar image nesswill nick5000 commented ·

Would 3 panels mvpp 41.96V / VOC49.45V still be able to startup the Multi RS in most conditions?

Hi i can answer this as i have done it on a SmartSolar MPPT RS 450/100 - yes it works on x3 panels 550w with a VOC49.85V, so x3 would be ok up to x8 panels.

The MPPT spec is very similar.

Hope this helps a bit.

EDIT:

FYI - 3 panels @ 7:35 this morning in Absorption on a SmartSolar MPPT RS 450/100.

low.jpg

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nick5000 avatar image nick5000 nesswill commented ·
Great, thanks! The screenshot shows 97.79V, does that means it started up below 120V? or did you have 120V earlier?

Any experience with partial shading of a panel, how much will that reduce the voltage?

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Alexandra avatar image Alexandra ♦ nick5000 commented ·

@nick5000

So the MPPT needs 120v to start but can then pull it down and track lower than that. The voltage is reduced drastically under shading but there is partial shading detection in the settings that seems to help. how much it reduces the voltage depends on how many of the sections are cut off on the panel and how the sections are set up.

Thank you @nesswill I was just looking into that and getting some data.

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