Using the grid only as a backup

Skid

Totally new to solar though I have searched various forums to try to learn as much as I can before asking stupid questions.

I live in Central America where the power is subsidized under 150KWH a month, doubling above that and a big increase above 300KWH. I regularly hear of foreigners  paying $500-600 and more per month. My usage with no pool, AC etc is fairly low but wanting a stable source of electricity and to keep my bill under 150KW I will soon have a couple panels, MPPT controller, inverter and 2 12v50ah Lifepo4 batteries to power a freezer at a price that will pay for itself in two years by supplying 30KWH a month.

I doubt the batteries will have the capacity from last sun to first sun and want to use the grid to only cover those 4-5 hours but not to charge the batteries and automatically switch from AC when the system has adequate power. Is there an automatic switch or type of inverter that can be programmed for this? I could simply let the freezer be without power that short time but I'd rather not.

Dave Angelini

What make inverter?
 Usually this is built-into the inverter. Schneider calls it self consumption, it is programmable and I can't remember what Outback calls it.
One can program a charge block to set times when the grid is being used and not.

There are a few other strategies for doing this. The battery may power the freezer but it will take alot of conservation to make this work the way I read it. Good Luck!

https://solar.schneider-electric.com/solution/residential-self-consumption/

Skid

Thank you. I was hoping for a simpler workaround but it will all be fine as it is. I will use a Samlex SSW-600. It turns out the LG inverter fridge uses a little more energy than the freezer, 1.2KWH a day so I will use the system for that and the inverter fridge should give a milder surge when cycling. The savings should be around $30 a month for an outlay of about $800-900.

Dave Angelini

The simple way is you are the controller and determine what is best

 If you want to automate it, there is where it can be an issue if you are not there. The good part is you get some back-up when the grid is out, even with a small system. If you have not bought the samlex, unless there is a reason for 12v, I would consider the 24v version if you want to expand later. Good Luck