Back-feeding AIMS Inverters

[LithiumSolar]

I've heard many times around the interwebs that there are people back-feeding the low-frequency AIMS inverters, without damage to the inverter, using a grid-tie inverter. The claim is that when the grid-tie inverter (connected to the AIMS output) is producing more power than being consumed, current is back-fed through the inverter and charges the batteries.

Is anyone here actively doing this? If yes, how has it worked out? I contacted AIMS support a while back and they stated that it cannot be done. I'm afraid to try it myself for the obvious reasons... Of course this does have the problem of the inverter having no way of knowing when the batteries are full and stopping the charging. That aside, I'm just curious if it can actually be done and thought this would be a great place to ask.

Thanks.

 

[SparkyJJO]

I think yes it works but like you said it cannot regulate the charge that way and you risk wrecking things.

 

[HighTechLab]

I've done it before, the thing about it is, the AIMS doesn't do frequency-shifting like a Sol-Ark for example. Once the batteries are full, the DC bus will continue to raise in voltage until the inverter shuts down on HVD.

If you are using lithium with a BMS, you could have some serious DC bus voltage spikes when the BMS cuts off.

 

[LithiumSolar]

I've done it before, the thing about it is, the AIMS doesn't do frequency-shifting like a Sol-Ark for example. Once the batteries are full, the DC bus will continue to raise in voltage until the inverter shuts down on HVD.

If you are using lithium with a BMS, you could have some serious DC bus voltage spikes when the BMS cuts off.

Interesting, thanks for the confirmation. Agree it has a lot of problems. I was just curious if I could use the big system as a "dump load" with a cheap grid-tie inverter, while testing batteries, rather than burning off 5kWh+ of power with a space heater. Even though it sounds like it would work fine, guess I'll just stick to the heater method to be safe.

 

[HighTechLab]

Interesting, thanks for the confirmation. Agree it has a lot of problems. I was just curious if I could use the big system as a "dump load" with a cheap grid-tie inverter, while testing batteries, rather than burning off 5kWh+ of power with a space heater. Even though it sounds like it would work fine, guess I'll just stick to the heater method to be safe.

Right now for quick capacity testing I'm running a Multiplus-compact 2000va in AC coupled fashion, that feeds into a 120/240v panel that has a Sol-Ark AC coupled with CT's on the feeders; I have the Sol-Ark set in "limited to home" mode, which means that it will do everything in its ability to prevent juice from feeding the grid (Obviously if batteries are full, it can't pull it from the panel to prevent it from going to grid, so it would feed the grid and I don't have a net metering agreement, so that could be bad). The way I run it is first charging the batteries with the batteries attached to the sol-ark, then run it backward and I always have room due to inefficiency (and other loads pulling from this panel).