question

yonkikkert avatar image
yonkikkert asked

What is best way to dump excess solar power into water heating?

I'd like to use an EasySolar for an off-grid solar with no AC input except genset when needed. How do I dump excess solar power into water heating after battery bank is on float without AC input? And without just installing a manually operated switch? Cheers Yon

EasySolar All-in-One
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2 Answers
tim-caesens avatar image
tim-caesens answered ·

I had the idea to switch on a boiler when SOC is 99% and switch of when 95% or something around this value.

Avantage: the easysolar has a programmable switch already, no aditional equipment needed, easy to setup, all solar power will be used

disavantage: can use a little bit of battery power

more advanced is using a "modbus dimmer module"

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reginald-potts avatar image
reginald-potts answered ·

Don't use float to trigger hot water heating as it could cloud up soon after switching and if the battery remains in float it will drain quickly. Better to use battery SOC if you can and programme a relay to close at 99% SOC and open at 98%. This is pretty bullet proof and will use most of the surplus power but make sure that 'surplus' is enough to drive the immersion heater fully or it will just keep cycling on & off every few mins. ie for a 3KW immersion make sure your surplus is well over 3000W

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