24 volt AiO inverter.. Just when I think I have it figured out

[kdiver58]

I have my 24 volt battery built. I need to order an inverter. I had finally decided on the

Growatt 3kW Stackable Off-Grid Inverter | SPF 3000TL LVM-24P.

But I just watched a Signature solar video on YouTube that recommended using a separate charger for charging the batteries when using this inverter.

One of Will's videos shows just adding an extension cord to a MPP AiO for charging a small off grid system but the MPP is only 2KW.

On the Growatt if I set the LCD setting 3 to “APL 03” can I get away with just using a cord to charge?

Does anyone have a suggestion for an AiO with a 24 Volt input and 2.5-3.0 Kw/120volt output? Under $800 .. Thanks K

 

[Bobert]

Hears the deal with AIO inverters. The amperage required to charge your batteries must be added to the amperage being used from loads on the unit because when using grid to charge your batteries the inverter does not run and the incoming power passes through to your loads. if you want to have a set and forget system you must supply clean power at the max charge rate amps + the max pass through amps. Yes you can connect the growatt to a cord but you must either limit your loads and or set your charge rate lower to sustain your loads while charging. This means that while you are charging your batteries from the grid your available power from the inverter will be a fraction of it’s capacity. Make sure your incoming cord is fused properly so that you don’t accidentally fry your extension cord. If you trip a breaker for the cord suppling your AIO it’s no big deal the AIO unit is designed for power failure but if the cord is over fused the cord ca fail and possibly start a fire. If you are using a generator it gets a bit more complicated because a standard generator will only supply cleanish power at between 50 and 60% of it’s rated capacity. Dirty power can potentially ruin the AIO unit. Technically you need a humongous generator to supply an AIO with clean power. I get around this in my situation by using an inverter generator that gives me clean power at full load.

If you want a set and forget system you can use an AIO in conjunction with an ac to dc charger that supplies power directly to the battery so that you don’t use pass through. Another option is to go with a more modular system. Many victron inverters have a power sharing system where you can set the max incoming amps and the unit will subsidize power when your loads exceed incoming power and charge your batteries with and extra power if your loads are less than incoming power. Expensive but very nice.
FYI incoming solar power can be set to charge your batteries in addition to the incoming ac power. If your available solar exceeds the limitations of your AIO you can simply add a MPPT solar charge controller to the system.

 

[kdiver58]

Thank you .. I was clearly overthinking this and added a level of confusion that should not have existed. It now makes perfect sense. Your wording removed all doubt. 100% of the time I would be charging by cord it would be without load. Problem solved.