First solar build in my camper

[JamesRich]

Does your friend have one? Also, what size is his camper? Also yours?

I have a fifth wheel and a 12 volt AC would be impractical for 250 square feet. I’d need a 15k btu AC which if I could find an 12 volt inverter AC would probably pull 120 amps.

No friend doesn’t have the 12 volt ac he’s just read about them. He has a 19 foot camper so he doesn’t need much. My fifth wheel is 34 foot 305 sf. It has two ac units, a 15k main over the kitchen / living & a 13.5k over the front bedroom. They both blow into the same duct work so I can run either unit to cool the whole camper. The main will cool the camper by itself just runs more than with both on. When on 30 amp outlets I can only run one anyway. The largest 12 volt I found was 12k & way too expensive! I can buy more batteries for less money.

 

[chrisski]

No friend doesn’t have the 12 volt ac he’s just read about them.

Please don’t listen to him. For reasons already mentioned a 12 volt AC is not practical if even available.

I also have a fifth wheel with two 15k BTU ACs, and IMO, installing a mini split will not work, at least I don’t want to be the first to install a mini split with my own money. A single 15 k BTU won’t keep up with the heat in that big RV and the mini-splits max out at 12k BTU at 120 volts. Installing enough cooling with mini splits would be difficult.

If one AC can keep the fifth wheel cool for you, consider yourself lucky.

 

[Zwy]

A 50 amp RV service is 240V split phase.

Having said that, be aware a pedestal may not be wired correctly. https://manuals.heartlandowners.org...o/Understanding 50 Amp Shore Power System.pdf

 

[chrisski]

A 50 amp RV service is 240V split phase.

For a mini spit and my RV, the problem is producing 240 volts split phase is a bit much.

At the very least, this would require putting a split phase inverter in. The lesser expensive things would be rewiring the inverter to Shore Power connector, and possibly thicker battery wires to get the extra power. Also not sure I could keep up with the extra power requirement. Also, now that the AC would be wired split phase, I would not turn that AC on from shore power unless I checked the input to be sure the RV park wired it correctly.

Not sure how much power a 16k BTU or 24 k BTU mini-split would pull, but once I get above 1800 watts for the AC, I need to add more panels to keep up with the added power requirement. Don't think a single 24 k BTU would exceed the limits of a

This is part of what makes the 240 volt install so hard.

 

[Zwy]

For a mini spit and my RV, the problem is producing 240 volts split phase is a bit much.

At the very least, this would require putting a split phase inverter in.

It would depend on the watts needed as to what size would be needed. Some AIO's have 240V split phase in a single unit. 48V inverter and that keeps cable size down.

The lesser expensive things would be rewiring the inverter to Shore Power connector, and possibly thicker battery wires to get the extra power. Also not sure I could keep up with the extra power requirement.

It will take less watts than the current roof air units with an inverter mini split.

Also, now that the AC would be wired split phase, I would not turn that AC on from shore power unless I checked the input to be sure the RV park wired it correctly.

Some surge protectors will check for correct 240V split phase and lock out if not wired correctly.

Not sure how much power a 16k BTU or 24 k BTU mini-split would pull, but once I get above 1800 watts for the AC, I need to add more panels to keep up with the added power requirement. Don't think a single 24 k BTU would exceed the limits of a

1800 watts should be easy enough. 12K BTU 240V Pioneer in my house draws about 1000W or less on initial cooldown (more like 800W), then it drops considerably. Usually less than 500W. One could turn on one, then the other. I think with 1800W though you probably could run both on initial cooldown. I do know in the evening after the sun goes down I see about 600 to 800W total draw on my system with the mini split running and the standby power in my house is 300W plus any freezer or fridge running.

This is part of what makes the 240 volt install so hard.

Most 240V mini splits are rated higher in COP and SEER compared to 120V. No imbalance on legs either.

 

[chrisski]

12K BTU 240V Pioneer in my house draws about 1000W or less on initial cooldown (more like 800W), then it drops considerably. Usually less than 500W. One could turn on one, then the other. I think with 1800W though you probably could run both on initial cooldown. I do know in the evening after the sun goes down I see about 600 to 800W total draw on my system with the mini split running and the standby power in my house is 300W plus any freezer or fridge running.

That’s useful data thanks. Seems to draw as much as some 120 v mini-splits I looked at.

 

[Zwy]

That’s useful data thanks. Seems to draw as much as some 120 v mini-splits I looked at.

I can double check on heat mode tonight, it will get cold here. Usually around 300W at night in the summer if I haven't quite reached the set temp. These do have standby draw as the inside unit fan will run all night.

I just went thru Solar Assistant looking at the past data for the hottest day in July. At night, we used max just 800W thru the whole night and minimum of 500W. I assume the 300W spike was the fridge running as it was pretty steady on cycling on and this same behavior shows up everyday even with the heat pump off. Base load with no AC running is always around 150W.

So yes, about 300 to 350W load to run the mini split thru the night. Over 10 hours would be 3 to 3.5Kwh.

 

[JamesRich]

Did some more experimenting! Bought a litime 30 amp mppt solar charger & hooked it to the batteries. I don’t have any panels yet so I dug out an old 24 volt power supply I had & hooked it to the power in. I put a clamp on amp meter on the inverter positive & started one heavy draw at a time. The ACs are supposed to be different sizes but they both make the inverter draw 110 dc amps while running. What surprised me was with the AC running the charge controller keeps the batteries at 13 volts only putting 8 amps in. So it was maintaining the battery voltage & the power supply was only pulling 2.5 ac amps from my house plug. The microwave is a big draw at 130 dc amps & the hot water heater pulls 130 too. That’s all the heavy draws though & the ac is the only one that would run frequent. Makes me feel a little better than my test with the ac running without anything charging. Now I just need to order some panels!
James