Maybe the last a/c solar question thread ever

[ROMN8R]

I'm a NOOB on this forum but not a NOOB to forums. I also tried searching and found endless threads on A/C systems that run off solar but it seems like most of them get left un answered because of someone not sharing their specifications goals battery capacity etc.

I'm hoping that this one can be a success story of peoples systems?


I currently have a 2002 International 8 window bus with the 7.3 desiel engine with NO A/C what's so ever. Nothing on the engine or remote. I have only removed the interior seating and I am in the planning stages of the build. Which is why this question for me is coming up.

I am married with an almost 5 year old and a 10 month old so we feel it is necessary to have an A/C system that can run while driving down the road as well as parked. Most of our time will be plugged in while camping or parked at a friends homes but we would like to venture to other places that will not have shore power. Such as race tracks (I have a car that I will be pulling on a trailer to different road courses and many of them have RV parking but no power hook ups) as well as the beach and very remote places. Most of our use will not be pulling a trailer with a car it will just be the bus.

I do not have a problem carrying a generator but I would like to cool the bus with some sort of A/C system that can be used only by solar. I appologize now because I know that statement is not correct and I understand that the A/C will be powered by some sort of battery bank that is charged by solar. I also don't need it to be a chilly 68 degrees 24 hours a day but more like a managable temperature since we are in TX and most of our travels will be in the summer months.

I've heard of soft start mini splits

I have no problem with any sort of A/C system as long as we can run it off of the solar

I also heard of something that is sort of a helper to get it kicked on.

I believe lithium ion large batteries would be best (no idea how many) but I understand they can be ran much lower than most.

I have no problem insulating the bus but I am planning on keeping most of the original windows

I hope that ya'll can share your experiences or what you've learned that you should have done and any suggestions or info on doing this.

If there is a thread out there like this already please forgive me. I don't mean to contribute to the clutter.

Thanks in advance!

[HazMatt]

Howdy from Grimes County!
I will be following this thread, being in the same boat as all y'all.
Literally! '98 8 window bus...
One thing I can answer is you'll want a soft-start capacitor for the A/C. Makes for less of a power spike on start up.
I'm keeping all of my windows, but this Sun blazing in contributes to the thermal loading. What I've done is to cut Reflectix panels to fit. Uppers can be made to stay up on their own, the bottom windows need help, taped or braced in place. They've made for a significant improvement in my mobile greenhouse!
So it looks like a baked potato from the outside. I like baked potatoes. So long's it's not my taters being broiled!
Some light filters thru, so it isn't a blackout condition, which I also like...
Happy Trails, and welcome to the looney bin!

[john61ct]

won't be the last I promise

You need a genset even if you can fit multiple kW of panels on the roof.

You will not be able to run the aircon off the panels **and** recharge a large bank at the same time, unless going to maybe 2-3kW of panels.

Running off genny will be needed for sub-optimal conditions, so the large investment in solar+batteries+inverter in the end just **reduces** your genny runtime.

At the cost of having to park in full sun all day.

There are plenty of 16000 btu aircon units that will run off a Honda eu2000i, get that sorted first.

Then work on the battery bank, figure 100AH **additional** capacity for each hour you want to run between genny cycles. Total incremental cost over the above will be several thousand USD at least.

The biggest challenge will be getting the energy you take out of the battery bank, back in. You need shore power or a genny running nearly as long as the aircon did, that huge very expensive battery bank just buys you some time shifting.

Need **lots** of solar for the long tail back to 100% Full, unless the bank is LFP, which is **very** pricey.

But solar will only give you 10-20% of the total energy needed, and that's only with a huge roof space to mount it, much bigger than the aircon will cool even with very tight sealing and 2-3" insulation.

If you need to run the aircon same time you're re-charging the bank you need double the amps input from mains, power or gensets.

See? The issue is **total energy needed** per 24 hours, voltage is really irrelevant!

Saving on the cost of the inverter will be trivial, and wiped out by the extra cost of a DC-powered aircon unit, which will likely be 48V, add other expenses then converting from that to 12V for everything else.

So stick with AC-powered aircon units to save some money.

Frigomar, Webasto, Dometic. . .

[john61ct]

Of course the best strategy is follow the 60's, go up into the mountains, work your way north as it gets too hot