Spare Growatt as charger

[reiters]

I have an extra Growatt 5000es. I have a large generator that is not connected since I converted to solar. I am trying to think of a good way to have the generator available as a last resort. My idea is to configure the spare inverter as 80a grid charging with zero solar charging. Not connect it in parallel with others. Just stand alone with its 240vac source directly connected to the generator. If it so happens that the power is out and batteries starting to run low I would go start genset and turn on that inverter to just push 80a into the batteries WHILE the paralleled set of inverters run the house from the same set of batteries. Is their something wrong with my thinking?

The though is that the generator is more than capable to handling any load I could ever put on it BUT it drinks 1.5 gallons an hour. If I hook it to the battery charger and charge the batteries at high current then I'm getting the most out of that fuel. If I run the house from the generator then it's not loaded heavy and only useful while it drinking fuel. If I'm charging the batteries then I could fill the batteries in a couple hours and run my house from them for several hours. If I had a larger battery charger then I'd use it but I don't have more money to throw at this and have the spare inverter. This would cost me under $100 in wire.

 

[timselectric]

Yup, that's the perfect solution.
I'm doing the same thing. Because it's cheaper than an 80a AC charger.

 

[B-Mod]

80 amps charging to battery is about 17.5 amps on the 240v ac from generator.

 

[reiters]

80 amps charging to battery is about 17.5 amps on the 240v ac from generator.

That's the max the growatt is able to do or I'd kick it up more. I'd love to push 150a to the batteries but I can't go and buy more chargers or a bigger one. Thanks for the input.

 

[reiters]

Yup, that's the perfect solution.
I'm doing the same thing. Because it's cheaper than an 80a AC charger.

Thanks for the input. Looks like your setup is very similar to mine.

 

[timselectric]

Thanks for the input. Looks like your setup is very similar to mine.

Still in the process of building my system.
But the plan is for two backup inverters connected to a 30a/240v power source. Dialed back to 55a charging each. For a total of 110a charging.

 

[reiters]

Still in the process of building my system.
But the plan is for two backup inverters connected to a 30a/240v power source. Dialed back to 55a charging each. For a total of 110a charging.

I initially set up as 4 inverters paralleled and 6xEG4 batteries hooked to 21,360w solar. I knew my loads didn't need 4 inverters but I wanted the extra solar input (based un uneducated calculations). Once it all was up and running, the batteries were filling up too early and wasting the rest of the days solar so I peeled 1/4 solar away and hooked it to a grid tie. Now I'm running the house off the 3 x 5000es and the batteries. The grid tie is pushing 20kw back to the grid each day to cover days that the batteries don't make it through the night or its cloudy. The 4th inverter is SHTF spare now so I thought I'd wire it to the genset as a battery charger. I know I don't have enough batteries to go days without grid and live my life normal but if the SHTF I can change my lifestyle so that it does. I don't expect to ever get my money back out of this system but that's not why I built it. It is nice that my electric bill is a fixed number now. My bills were $200-$450/mo (Texas summers are expensive). Now I just pay a fixed loan payment amount. A financial advisor would say it was a bad investment but I'm happy with my choices.

 

[timselectric]

I look at it as pre paying for all of my future electrical requirements. So far I have knocked a third of my bill off. Hopefully after this winter I will be completely off the grid. Provided I find the time to complete my system.

 

[reiters]

I am mostly off-grid. Cloudy days or wife cooking a roast in the evening will run my batteries dead at night. Most days zero grid used but sometimes up to 10kw used. I am pushing 18-20kw a day thru grid-tie so I bank way more than im using. Sadly they pay much less than they charge so its pretty wasteful to send more than I use. I'm on par to completely zero my grid bill. It's a $40 base rate so takes a lot at $0.08/kw

 

[reiters]

I finally got around to rewiring and I am very pleased with result. I am pushing 80a to the batteries and the generator is at 31% load. It's charging the batteries at around 15% per hour. I will just run it one hour. It's a cloudy day and the generator hasn't been run for a few months so it's good for it to get warmed up. Thanks everyone!

 

[myles]

I finally got around to rewiring and I am very pleased with result. I am pushing 80a to the batteries and the generator is at 31% load. It's charging the batteries at around 15% per hour. I will just run it one hour. It's a cloudy day and the generator hasn't been run for a few months so it's good for it to get warmed up. Thanks everyone!

what did you end up doing for growatt settings? did you find that you need to start the amps low and then increase them as the generator is running, or do you just start the charging at 80A? What is the charge bulk voltages you uhave set?

 

[reiters]

My generator is large and can handle much more load than I am applying to it. I have been playing with the bulk charge. I have it set to 55.5v. I chose that because its below the spec on the batteries. I try to stay on the safe side. These settings charge the batteries at 14A each (0.14C)