Off Grid Home Forums Technical Discussion One system or two/////////Overflow power//////Air conditioning Re: One system or two/////////Overflow power//////Air conditioning


Thanks for the reply and ideas.

As for geothermal…I dont think the water temp is cool enough. Often water in the hot tropics is still cool cause it comes from high mountains but mine is from a very low mountain (700 feet elevation at peak less than a mile away and I’m at 160 feet). Do you have any idea how cool it would have to be? I do plan on surrounding most of the perimeter with a man made “creek/aquaponics system/natural passive swamp cooler”. I will also draw my air in through pipes laid below the water. And I would shut down the passive vents when using AC (although if the ac is automated based on excess power that might be really complicated).

As for swamp cooler I was under the impression that they did not work very well with high humidity. The area I’m in is a true lowland rainforest and humidity averages about %500 (at least thats what it feels like). I had one growing up in Florida and it was pretty good but it ran of aquifer water that I presume was pretty cool.

I will certainly investigate both these ideas before proceeding.

As for the solar…I was planning 2 x 200 watt pv for the dedicated 12 volt system. You said 500 so I figure without the computer I’d be fine. You also said 1 system but if I have one @ 400 or 500 watt that leaves me virtually nothing for everything else. This project is mildly commercial, will include a hobby farm and will see decades of slow development so an addition system (probably at 120v…from inverter based on 12v batteries) is basically mandatory for a freezer, tool charger, occasional tv, blender, a few lights (I’m sure I’m forgetting something). On top of that the first system is so important that if it ever went down I would be ruined (aquaponics and computer HAVE TO have power) so a backup would be nice. I can live without AC and frozen fruit but if the computer goes down my income dies with it and if the aquaponic pump dies my fish die with it (my food and income are priorities). Not to mention the smell of a self composting toilet without a vent fan.

I have an internet business (the only reason I have the option to move off-grid) I don’t need to be online very often but I spend at least 2 hours a day on my laptop (so its a predictable power consumption like the other items listed but the time of use varies unlike the rest). I also feel having a fruit tree farm and tourists in the same place makes having frozen fruit, smoothies and meat storage really important.

As for running the AC on excess power. I think you used the term power dump…is that the idea of using “extra” power after the batteries are full? Would one of those AC units you recommended run from the power directly from the panel. Or is there a way to run one directly from the panel.

I have also considered having an ac unit that I only plug in when the batteries are full charged AND the solar is being generated at full capacity. Is this math close to correct: If a 500 amp 12v battery pack (6000 watts) is fully charged and the panels are generating 500 watts (wasted per hour cause the batteries are full from say 2-3 pm) And I run a 1000 watt AC for 30 minutes (500 watts) then the batteries suffered virtually no drain (assuming nothing else is running on them)? This is a serious compromise because I would only be interested in AC for sleeping hours (maybe I’ll have to adopt to the siesta culture). Basically, I am curios about a technology or controller that would do this for me automatically…but I guess I should confirm that it works in theory first!?!

Thanks again for the help and I don’t want to act like I am ignoring your advice but I think you underestimated the scale of the system (my needs). I am also pretty clueless about this stuff so I’m probably overly ambitious…lol