Solar Generator Newbie

[philatio]

Ever since I cancelled my Bluetti order, I have been itching to put my own solar generator together. I have a 10.4 KW grid tied system already but want to put together something off grid as a general battery backup.

An electrician has already installed a 10 circuit transfer switch along with the accompanying L14-30P inlet box in my garage. I want to utilize this in the simplest, SAFEST manor possible.

I may add additional PV directly to the off grid inverter later, but I currently generate more than I use and figure I can charge batteries directly from the mains and still come out ahead.

In a grid down, my PV system (SMA Sunny Boy 7.7) has the secure power supply that I could use as AC charging for the off grid batteries. Up to 2000 watts during the day in the sun is out.

The grid in my location is fairly stable. Even during the Texas freeze out last February I had intermittent power. One hour on, 2 hours off etc, so for now, I just want to experiment and I can expand later. Having the transfer switch will allow me to do some battery cycling as I can run off the battery backup even if the grid is up. The transfer switch is a break it before make system (Reliance 310C).

The image shows an L14-30R for AC input, however I have two dedicated 20A circuits already installed as that was how I was going to charge my 2 x Bluetti AC300 & 4 B300 batteries. In order to do it this was, Bluetti required two circuit on the same phase. This is how it was wired at the same time transfer switch was installed. I would like to utilize these if possible so I don't have to rewire with a L14-30R outlet.

This is my newbie take on what I would like to do. Would this work or is it an accident waiting to happen?
I'm open to comments and constructive criticisms.

Thanks in advance

 

[12VoltInstalls]

I don’t think that’s a bad idea. Some loss with the charger but it should work.
I’d calculate your 10 backup circuits and just make sure you have like 24hrs+ for your needs (theory is that’s like barely enough for an overnight and a cloudy day. You might have less or more time that you prefer)

 

[philatio]

Thanks for the feedback.

I installed a sense home energy monitor a couple of months ago. At this very moment, with my pc on, 65" TV and related sound setup on, my media server on, related switches and modem, and the other vampire draws such as security system including cameras, I am using 850 watts. Of course it fluctuates, but that my average work day base line draw. When my heat pump kicks on for heat or AC, I'm still below 3000 watts and that cycles for about 15 minute once or twice an hour. The heat pump is 240V but is on a 25A breaker.

I kept all the huge loads off the the transfer switch ... water heater, dryer, range, dishwasher, washer, and I left the "emergency heat" resistive heater coils out as well. I think I'm good with the energy audit I have done, and I will add batteries as I go.

Just want to be sure I don't need any breakers/protections between the inverter and generator inlet box, and between the AC outlet and the inverter.

Is it possible to use the AC charging setup I already have? Dedicated 20A out versus wiring up a 30A outlet?

Again, thanks for the input.