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timbo avatar image
timbo asked

Is it possible to include Tesla Powerwall 2 in AC-coupled off-grid system based on Victron Multi?

Hi everyone!

I have an AC coupled off-grid system: MultiPlus 48/5000, 6kW solar panels, grid-type solar inverter Schneider Conext RL 5kW, 20kWh of lithium batteries.

Multi creates a grid and through frequency shift controls solar inverter. Solar panels generate electricity and through inverter feed my house and charge lithium batteries. Everything works almost fine.

Now I'm considering to expand the system to include more solar panels and storage. My primary interest is solar panels as sometimes I need more power from solar, for example to run air conditioner on a very hot day, when panel production deteriorates.

Adding more panels to the same system with single Multi is not recommended by 1-to-1 rule. I was thinking if it might be possible to add Tesla Powerwall with its own set of solar panels. Powerwall available in Australia is AC coupled and for grid applications only. I guess Powerwall should consider a grid created by Multi as a real one and feed the house and the grid itself. And Multi should be able to balance its own power with the power available in the grid.

Is there any major problem in this setup? Should I keep thinking in this direction?

Thank you.

Regards, Tim

MultiPlus Quattro Inverter Chargeroffgridpowerwall
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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi Timbo,

If the goal is to get extra solar production, the path of least resistance and cost would be to add the extra panels using a DC MPPT charge controller:

https://www.victronenergy.com/solar-charge-controllers

At 48V, the 150/100 will give you another 6kW of solar panels without the risk of overloading the Multi/Quattro from too much generation on the AC bus.

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timbo avatar image
timbo answered ·

Thank you for quick response Guy.

All roof space above Multi is filled with panels already. New panels might go about 100-200 meters away from Multi (it's a big property). I'm not sure that low voltage DC controller can be connected from that far.

I was thinking about adding one more installation of solar panels with a grid-type inverted but with panels orientation different to the existing panels. I have 5/6kW setup with panels to North (it's Australia). I can add similar or a bit smaller setup with panels towards West. This way all solar panels combined will never get max possible generation. I estimate it might be close to 1-to-1.

An idea with Powerwall still looks interesting. Are there any major flaws?

Regards, Tim

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boekel avatar image boekel ♦ commented ·

if you install the mppt close to the batteries, and maybe choose a 250 volt model, the cable losses will be small.

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wkirby avatar image wkirby ♦♦ boekel ♦ commented ·

DC is even less cable losses than AC (skin effect).

+1 for 250V MPPT.

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gprado avatar image gprado commented ·

What was your ultimate decision in the Powerball? I have a similar situation.

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