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bob-thompson asked

MPPT 75/15 voltages

Quick question. I have two 100 Ah AGM batteries fed by an MPPT 75/15 and a 400watt PV in my house. I use very little energy from the batteries day by day.

To maximise the solar electricity generated, I have considered either, buying a small 12 volt to 230 volt invertor and plugging my Starlink internet system into it, or finding a gadget that would feed in 230 volts into the house electrical system when the batteries are full, therefore something that would need to be able to measure and switch.
Would any old inverter off ebay be the solution to the first option?
Is there a gadget that can do the second option?

MPPT SmartSolar
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matt1309 avatar image matt1309 commented ·
Hi @Bob Thompson


If you have a relay or some for of switch you can programmatically activate when the battery is full. (voltage may even be a good enough metric for AGM batteries), then i imagine any inverter with a switch might be ok.


I'm surprised you cant power starlink on 12v? Saything that you'd need to make sure you never needed to switch it back to AC power in the event battery died.


Second option, multiplus ii do exactly this. They're expensive but what you describe of feeding into the grid, or even seperate off grid 240vac circuits is possible with a multiplus ii

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bob-thompson avatar image bob-thompson matt1309 commented ·

Thank you Matt. The Starlink works off around 48 volts as standard so 12 volts is not enough, I am a newby at this lark!

I looked at the multiplus ii but it would be mad to spend that amount of money, it is about the annual electricity bill for my house. This is just playing and learning for me.

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k-k answered ·

A 12VDC to 48VDC (buck-boost-)converter could be the solution for Starlink....

If Starlink needs 60W your system must deliver 24h * 0,06kW = 1,44kWh || so 2 AGMs à 100Ah * 12V = 2,4kWh - how many sunshine-hours do you have to have them always filled. (Assuming 60W 24h, but if winter-cold ~150W, summer = less)

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