How much Solar Power Do I Need?

Hypothetical: Let’s say you live in a hot, humid climate like, oh, I don’t know, the Texas Gulf Coast.

You have all the sunshine you could possibly want, and in summer you have a good 14 hours of it per day. The only problem is that it’s astonishingly hot and humid all night long and you want to use your roof A/C to keep cool and dry while you snooze the night away and to keep the mushrooms from growing in your shorts drawer.

The obvious solution, of course, would be to fill up ol’ Betsy with gas and head for northern New Mexico ASAP. But suppose that option wasn’t available for some reason. Remember, this is all hypothetical; a sane person would just bail and head for the mountains.

I’m not smart enough to calculate this on my own, so can anyone tell me how much battery it would take to do the job and how much solar that battery group would need to recharge during the day enough to run the A/C all night. Let’s assume for the moment that all the other needs are taken care of – just talking about the requirements for the A/C in this discussion. Also, to narrow the field, let’s assume just one single, normal sized A/C unit in a small TT or Class C.

Whaddya think?


Est 6ah x 12hours = 72ah

So battery pack of 200ah would work if you recharged them everyday.

300w solar = about 80+ah day

So 200ah+ batteries and 300w solar is my hypothetical answer. :sunglasses:

These numbers are rough. If I’m way off, someone please correct me.


Thanks for the speedy reply :hearts:. I will continue to do more research on this

I’m gonna keep posted because I have the same question being here in Miami. We’re just trying to escape the hot nights. If I come across any info I’ll share it with you.


Let us know what you find out. Im sure many others have the same question as well. Thanks :slight_smile:

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I have 160w panels and a 100ah battery. I do not run an ac though. I have plenty of battery to run my fridge and fan for cooling on those hot nights. The key is to open a couple windows with the fan and get good air flow. (Make sure you have fly wire to keep those bugs out)


I’m no math whiz but in my research on this topic, I was told by multiple sources (including Bob wells’ book) that solar to run AC it’s completely. This is a very popular topic over at skoolie. net forums.

I don’t want to be rude but I’m pretty sure your math is way off or most of us would have solar powered air conditioners.


This a why I just go for the good air flow and a small 12v fan :+1::ok_hand:


Exactly! I actually just use a couple battery powered fans. They’re super cheap. Kind of offsets there price of batteries. My 8" fan takes 8 D cells and my 3" fan only takes 2. One set of batteries lasts most of a spring/summer, but then again I can use them sparingly because I travel with the seasons and wouldn’t be caught dead in the gulf for the summer


2 posts were split to a new topic: What 12 volt fan are you running?

Hey! I dont know how much solar you would need but since its for ventilaton, maybe this is an option to consider. Ive bought one of these solar ventilation fans and they seem to be pretty good. I havent installed it yet so I dont know for sure. According to the specs it can run for 8 hours after only 2 hours of charging in full sunlight and for 20 hours when it is fully charged which means ventilation all night long. So if you are in a sunny area it seems like a really nice and easy option. You can have 2 or more of them, E.g. one for exhaust and one for intake. There’s more info on the site. :slight_smile:


Yo @bizness. So I know this is a UK company but they are great with solar equipment and they also have a calculator on their website!


That sounds like a really useful resource. Could you post the link to the calculator. I am having trouble finding it.

Hey @HenryCooper apologies for the slow response here it is, Solar Calculator

I’m currently working in Bali and get back to the UK 27th, pic up the van 28th and have an appointment with these guys on the 29th to advise and design a solar System. For UK/EU van lifers I highly recommend these guys!


Just book marked it.

Seems like a great tool for pretty much anyone thinking about solar. Thanks for the share!

Most of the folks running A/C off solar are running 1000w-1400w + big banks, and only running it during the day and maybe an hour after sundown. This is for an energy-efficient window type unit. Generally speaking solar A/C is not practical in a van.

“[solar powered A/C is] not a lost cause… we just seem to be at that frustrating cusp where it’s technically possible with current technology, just not easy or cheap.” – thatswhatsup

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