Prioritize Solar over Shore Power

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ghgd asked Feb 18, '23

Prioritize Solar over Shore Power

I have read what I could about this, but have not seen a simple solution. I have 1000W of panels with Multiplus 12/3000/120, 150/85 MPPT Charge Controller and CerboGX / Touch50, 3 x 200Ah Lithium. I shut off Shore Power completely Late Spring thru Fall and all is good, but during the winter months I want to take advantage of all Solar, when available. Shore Power powers all AC, and solar kicks in for the DC demands. I have currently limited Shore power input to 12 amps. Should I lower that even more and find a balance, which will keep the batteries up, or is there a setting where Solar can be utilized to its max whenever available, and Grid/Shore to take up the balance. I know I am being simplistic here, but I am looking for a straight forward solution.

solar shorepower

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Answer 1 · 2023-02-18T23:37:36Z

Ed Jones answered · Feb 18, 2023 at 11:37 PM

Check this out: https://community.victronenergy.com/questions/103497/force-multi-to-charge-although-ac-input-control-is.html?childToView=103937#comment-103937

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Answer 2 · 2023-02-19T03:42:54Z

JohnC answered · Feb 19, 2023 at 03:42 AM

Hi @GHGD

Solar will always take priority over the Multi charge if it's target setpoints are very slightly higher. Providing they're both at the same Charge State, and this can't be synchronized. First up, I'd use DVCC so that they both see exactly the same V.

Then consider setting the Multi at a flat, common Absorb/Float V, say 0.05V lower than the mppt Float. An optimum Float is a littte tricky with Li batts, as they have a very flat V curve, so you'd need to experiment to find that. Like if you have the Multi on all night for your electric blanket, you don't want to awaken to flat batts, nor find they're fully charged and the solar has nowhere to go. Even if full batts though, the solar will still push to Abs (for whatever time you set) and service loads.

This is the simplest way. Ed has suggested another, and I'd probably go straight to the Multi's Assistants and switch the Multi right out of it when it suits, like an offgridder and his genset.

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