Preface for why I have weird needs: I live in Lebanon. We get a few hours of “true” grid power per day. We also get a few hours of power from the local generator mafia (I really can’t go into detail, there’s a ton of info online). This has always been enough but the country has been going through an economic freefall so the hours are limited.
I also have limited roof space as this is an apartment. I did not purchase a system yet as almost all the local sellers are out of stock (because everyone that can afford it is adding solar now).
If there was only one source of “grid” power it wouldn’t be an issue, but the true grid is unreliable and has sporadic hours. It is however cheap and I can draw 30A out of it. This is what I’m routing through the hybrid inverter, so I can charge batteries with the cheap power in the winter and at night.
The generator power is a can of worms though. It’s expensive, but has slightly more predictable hours. It’s limited at a pitiful 5A though. Drawing any more means you have to run down several flights of stairs and flip a breaker across the street. This is my childhood home and I’ve done this diligently for over two decades anywhere between five and twenty times a day. Fun!
Since everyone in Lebanon has two “grids”, I expected all the solar companies to have elegant solutions for this problem. Some kind of priority system or some kind of threshold-driven priority PLC thing that switches intelligently to save as much battery as possible for the nights. No avail though. Their “solution” is to keep the in-home generator breaker off and use it only as a manual backup. I instead want to use it as an automatic supplement:
Does some kind of load distribution electrical fixture exist that would let me use a trickle of generator power during the generator hours, while still pulling the rest from the inverter? It would need to pull all the power from the inverter when the generator is offline. A selectable current limiter would be nice as well, as I might need to pull 5A in the winter but just 1A (or none) in the summer. I’m not worried about the true grid, that’s routed through the inverter and will be taken care of over there. I know phase things are an issue as well and honestly don’t know what to do with respect to that.
You might suggest routing the generator through the inverter and using a simple priority contactor to switch to the true grid when it comes, but most inverters I’ve seen have a minimum grid charge circuit current of 5A, which would just trip my breaker since I have other things in my house.
I’ve tried searching for a solution online but I can’t seem to find the device that does the load sharing. Hybrid inverters have one built-in, with digital current limit selection, so the device does exist. I just need to find its name.
EDIT: In case it wasn’t clear, it’s to get more power in the winter and at night. The generator service is there and I want to be able to use it to supplement my system enough for it to be completely self-sufficient when both grids are offline, especially in the winter/at night.
EDIT 2: I’ve also considered keeping the generator like disconnected from the house and just wired to a dedicated charger that goes straight to the batteries, efficiency losses be damned. But given that this is a hybrid inverter, I’m worried it would freak out and think the batteries caught fire from the sudden battery voltage fluctuations. Or worse, that the inverter could be drawing enough power from the batteries while the charger was powered that it could damage the charger, batteries, inverter, or any permutation of the three.
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Author Of this post: /u/gogetenks123