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harryt avatar image
harryt asked

Use Solar 'overcapacity' to connect Mppt 100/20 Load to a grid-tie inverter

Since my camper is parked near my house, it seems a littiebit of a waste not to use the solar-panel for another purpose than solely keep my battery healthy. So I thought: When my battery is topped-up I want to be able to switch the output to my grid tie-inverter. I thought I could use the LOAD-output of the Mppt for this purpose. Is there anyone who did this? I it correct to do it? The product I have is the Victron SmartSolar 100/20 12V

MPPT SmartSolargridmultigrid
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6 Answers
thanar avatar image
thanar answered ·

What's the specs of your grid-tie inverter? Grid-tie inverters usually have DC-in ports only for PV panels, where you intent to connect the MPPT onto?

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harryt avatar image harryt commented ·

victron-mppt-load-on-grid-tie-inverter.png


The picture shows what I do and how I connect things. The Grid-Tie Inverter can work with voltages between 10,6V and 20V, so since the Mppt load delivers 12V DC when it gets activated, i can feed it into the Grid-Tie inverter. I already got it working, but now I wonder if it is healthy for my battery, because say for instance I want the Load-ouput to go active when my battery reaches 13,4V (just an example), it thought it would would stop to bulk-load my Battery and start feeding the Solar power to the Grid-Tie inverter. But that isn't the case. What is does is: draw power from my battery until it reaches the lower boundary. Then, Load disconnects and the battery gets filled=up again until the 13,4V is reached and then again the cycle repeats. It seems that I'm supposed to use the Load output to send a signal to a relay which will make the solar panel toggle between "A: connected to the Mppt" / "B: connected to the Grid-Tie inverter".


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Justin Cook avatar image
Justin Cook answered ·

The load output is powered from the battery, not the PV input, so I suspect that would be counterproductive for you; also please note that inverters and other high-startup devices cannot be connected to the load output, as per the user manual:

SmartSolar 75-10 to 100-20 User Manual

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juliangoespro avatar image
juliangoespro answered ·

I am looking into doing the same! Did yu try it? Thanks!

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René V. (Sereen) avatar image
René V. (Sereen) answered ·

I was thinking of doing the same aswell but also read a lot about it that you can't use the load output connections for this. Not even when setting the AES options on the MPPT for it. So i was thinking of using a "a30 voltage controller" to turn off the MPPT and turn on a micro inverter (and vice versa) depending on the battery voltage.

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René V. (Sereen) avatar image
René V. (Sereen) answered ·

I tried the "a30 voltage controller" and it does work, however...

When the set voltage is reached then relay turns on, but then the battery recovers/rebalances end it switches again within a few seconds. So unfortunately this setup does not work as disered.

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kai-fuchs avatar image
kai-fuchs answered ·

Hey guys, I had the same idea but didn’t build it yet cause we’re on the road at the moment. I have additional to the MPPT a shunt in my system. The shunt is able to trigger a Relais based on SOC. My idea was to use the shunt to switch my solar panels from my Mppt to the grid inverter when the battery’s are full (99% SOC turn Relais on Power goes to grit, 90% SOC Relais off power goes to Mppt)

This sadly doesn’t work with a smart shunt.

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kai-fuchs avatar image kai-fuchs commented ·

Correction, even the shunt is not able to trigger a relays on a bigger (e.g. 99%) SOC then the relais clear condition (e.g. 90%). Even with a cerbo this needs to be programmed in NodeRed. Doing it in Node is fairly easy, so the only way achieving this task is through a Versus or Cerbo.

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