question

kolfleading avatar image

MultiPlus-II: Protect generator from feed-in

Planning a DC-coupled ESS with Multiplus-II (due to grid regulations) and 2 x Pylontech US2000 batteries and Grid Feed-In enabled.

Batteries are mainly for backup (feed-in tarriff works out cheaper than batteries per kWh transferred).

I also want to be able to connect a small generator and charge the batteries during longer power outages when battery SOC is insufficient to last through the night.

If I connect the generator to the AC in, I'm concerned that the Multiplus-II might try to feed-in to the generator.


1. Is there a way to automatically ensure that MultiPlus-II will not start inverting while on generator? Automatically switch it to "Charger Only" and pass-through to AC loads?


2. I could completely avoid the risk of feed-in to generator if I could find a charger that could connect directly from 230V AC generator to the batteries, so the generator would be kind of "DC-coupled"...but what charger would work for this type of batteries with built-in CAN BMS?


I have already read other similar questions like the one below, but the answer there would not work for me because I would really want to charge the batteries from the generator.

https://community.victronenergy.com/questions/20939/multiplus-ii-with-grid-injection-how-to-avoid-inje.html

Multiplus-IIGeneratorgrid
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2 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @kolfleading

Some grid-codes have an option to disable feed-in when an input is active (aux1), this might be the easiest solution.

Please note that a small generator could be difficult to get accepted by the Multi when using a grid code.

A separate charger will always work, especially with a small generator this might be best. you can use the 'allow to charge' contact of the Pylontech battery to control it. Some chargers (that connect through ve.bus or ve.can) can be controlled by the BMS through the GX device.

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dean-d avatar image
dean-d answered ·

@Daniël Boekel (Victron Energy Staff) We have an ESS installation set up with 2 x 5kW Multiplus 2 and 30kWh of BYD LVL batteries.

Our customer wants a generator backup for prolonged outages. We have tried a generator on AC input via a changeover switch. Although the NZ grid code will not accept it.

I'm thinking a Skyla charger straight to the battery bank. Do you know if this could work with this system?

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