Fire, Ready Aim

Armed with very little knowledge I bought (17) 240 watt used panels. The seller included 17 Enphase micro inverters, wiring to daisy chain the inverters, and mounting racks.

My goal is to have a charge controller and batteries to run a couple of mini split ACs. I have grid power but I'm not interested in sending power to the grid. Instead eventually I'd like to use grid power as a backup to my solar when my system is big enough. With this goal in mind I'm thinking I don't need the micro inverters, instead I'd let the all in one charge controller/inverter do the work. Am I thinking right?

Thanks!

I don't know much about grid-tie inverters at all but i suspect if you wanted to use those Enphases in an off-grid way you'd have to 'trick' them into doing it. You certainly could just ignore them and buy an all in one inverter/charger, although what kind would depend on the mini splits you're trying to run. Since mini splits don't really have 'startup surge' i would guess most 5-6kw inverter could run 2 mini splits at max settings unless one or both of the mini splits was very large (20k+ btu/hr). But you'll just have to look at the specs of the models you're considering and plan it out. If you wanted the inverter to power those AND do other things it would have to be a pretty large inverter, or you should buy something that is parallelable and that you could be pretty sure to still be able to find more of them when you get around to expanding the system.

Yeah why micro inverters...all you need is panels and an AIO.

nc73 said:

Yeah why micro inverters...all you need is panels and an AIO.

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I thought so, I just wanted to verify I wasn't missing something. Thanks for the reply!

I personally like going the redundant separate component route vs AIO. I've been burned to many times when one small part breaks, the whole ship goes down.

I like the simplicity and small package of the AIO.
And also agree that redundancy is important.
For redundancy I'm installing multiple stacked AIO's and multiple batteries. All of which can be isolated individually from the system for maintenance and or repair. Without shutting down the whole system.

timselectric said:

I like the simplicity and small package of the AIO.
And also agree that redundancy is important.
For redundancy I'm installing multiple stacked AIO's and multiple batteries. All of which can be isolated individually from the system for maintenance and or repair. Without shutting down the whole system.

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Sounds like the best of both worlds. I'm my own power company so I have to make sure it keeps going. The little people are counting on me.

sunsurfer said:

I personally like going the redundant separate component route vs AIO. I've been burned to many times when one small part breaks, the whole ship goes down.

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A good branded and quality All in one inverter is quite reliable nowadays. Get one of the units with a 5 or 10 year warranty and you're even safer

The micros may have value to someone. Depends on the model.

koobs said:

A good branded and quality All in one inverter is quite reliable nowadays. Get one of the units with a 5 or 10 year warranty and you're even safer

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It looks like a growing trend going forward. I guess the redundant option would be to keep spares on the shelf assuming one has that kind of budget. Assuming the world is still working(which it barely is at the moment), there would still be down time if you had just one unit running. That would suck to wait for the parts turn-around. As long as I can keep power going while I wait for warranty. The joys of being your own power, water, sewer company....

My off-grid farm property currently has a single All-in-one inverter running. Its a cheap ebay knock-off of an MPPsolar, from about 8 years ago. The solar charge controller internally broke and so I had to install a seperate SCC.
When I upgrade the system soon, I'm going with 2x 5kw All-in-one inverters, running in parallel. That way if one breaks, I can still run the other as a single 5kw unit. If both break at the same time, then I've got my 4kw LIFEPO4 camping battery and 2.5kw 12v inverter for critical loads. If thats not enough, then always got the petrol generator as back up. I think that's enough redundancy.

When i first went off-grid, the first thing i did was buy a huge 5k MSW 12v inverter from Harbor Freight. Not the nicest inverter, but supposed to be fairly reliable and locally warranty-able.

The reason i did that was that, as a car guy i have a bunch of cars sitting around. Between a bunch of cars and being able to locally exchange the msw inverter, i figured it was basically impossible for me to be without power longer than it took to drive to Harbor Freight. Seemed like a pretty bulletproof contingency. Now i have 2 large 48v inverters for the house, and 2 large 12v inverters hooked up to a large 12v 'bus' of around a dozen vehicles (including an rv, tractors, lawnmowers, cars/trucks, no motorcycles yet lol). Is it a 'good' power supply? Ehh.. not great. But is it capable of easily doing 1kw of backup power until the last drop of gas on this property is burned, and then for several hours afterwards until every single 12v battery is dead, all while barely turning on the fans on the giant inverter? Yeah, it'll do that. Oh yeah, 3 generators here too. There are about 60 solar panels hooked up on the property, and a pile of ~105 60w panels I have yet to get around to doing anything with.. I should be ok. Rube Goldberg's Survival Handbook. ?