Inverter on or off when connected to shore power?

[Larry A]

I have a 2021 Winnebago View. Should I turn the inverter on or leave it off while connected to shore power? Or does it matter? Also, does having it on or off affect the charging ability of the solar panels?

[creativepart]

Well, the answer is basically it doesn't matter.

I believe WBGO is installing Magnum inverters (1000w and optionally 2000w) with AC power pass through and a transfer switch in new Adventurers. So, when on generator or shore power the 110v passes through the inverter and is not drawing power from it.

I used to turn mine on and off all the time. But I'd forget to turn it on and I'd disconnect power and have to reset clocks, etc. Now, I leave mine on when the RV is plugged in. That way if the shore power cuts off or I start and stop the generator the auto transfer switch inside the inverter keeps everything powered up.

I'm sure you'll hear from others that always keep theirs off and feel strongly about it. But there is not much downside to leaving it on that I've experienced.

Of course, in storage, or when sitting for any extended period without the engine running, shore power present or the genset on will fairly quickly deplete your batteries. I had my inverter on when I bought home my RV from storage and the residential fridge was running. I parked and delayed connecting the 30-amp power I have at my house for what I figured would be about 30-mins and forgot about it all day. I didn't deplete my batteries, but took about 40% of their stored power before I got around to plugging in. I guess that's the biggest risk.

As to your solar panels. You need to think of them as a totally separate system. The panels are plugged into your solar charge controller and that controller is directly attached to your battery bank. Everything is completely separate from your RVs electrical system.

It is normal for your solar charge controller to vary the amount of power it delivers to your batteries based upon their state of charge as determined by the bank's voltage. When your batteries are over 12.6v your solar charge controller reduces the amount of power it delivers to your batteries and this is regardless of you being parked in full-sun on a bright sunny day.

So, when you are plugged into shore power, running the engine or running the generator you are charging your battery and this brings the battery voltage up over 13v. So, the solar charge controller sees that voltage and reduces it's output to at or near zero amps.

Even depleted batteries that at rest would measure 11.7v will show the charging voltage when they are being charged. So, if a charger is applying 13.9v those depleted batteries will been seen as full charged by your solar charge controller.

Folks like to think that their solar panels are adding even more power over and above their other battery chargers - but that's not how this works.

[Larry A]

Thank you very much for the quick & excellent reply. I thought that it probably didn't matter about the inverter, but wanted to make sure. Also, thanks for the information on the solar charging - I wasn't sure that the charging would still take place if one of the switches (coach on/off or invertor on/off) was not on. Apparently, it doesn't need either to be on.

[creativepart]

Originally Posted by Larry A

I wasn't sure that the charging would still take place if one of the switches (coach on/off or invertor on/off) was not on. Apparently, it doesn't need either to be on.

Nope, that doesn't matter either. Which is great if you store your RV outside. You can turn all of the battery disconnects off and know that your solar panel is keeping your batteries all charged up.

I store my RV outdoors, uncovered, and when I pick up the RV it's perennially at 100% State of Charge. Oh, that brings up another thing - I strongly recommend installing a shunt-based Battery Monitor Kit. This is an easy self install if you are even a little bit handy at DIY tasks.

The BMK will monitor all power in and out of your batter bank in amp hours instead of voltage which is easier to understand and more detailed. It will show you your battery bank's state of charge in percentages. So, when your batteries are 32%, or whatever, depleted you know for certain how much power you have. And the best ones will tell you how many hours remaining until empty at your current rate of discharge.