Totally Solar

[RVGuy1966]

I am wondering if anyone has gone so elaborate as to have enough solar and batteries with the the right inverter to actually run their AC for a short time? although impractical I cant imagine with todays options if anyone has made this a weekend project. I would be curious to know what was involved and how long they got it to work if at all.

[JFNM]

I have not. However; it is certainly possible - just not realistic. With enough solar panels, very large battery bank, humongous inverter and cables; it can be done. The problem is that most of us do not have enough space for the panels or the batteries (never mind weight or cost) to get an hour or two of AC use. Just a guess but I wouldn't be surprised if all this weighed 3-4 thousand pounds and cost $10k or more.

Running the numbers is not be difficult - guessing that one AC is about 1800 watts. 1800 x 2 (AC units) = 3600 watts. 3600 watts = 288 amps (at 12.5 volts). So you would need 1152 amp hours for four hours of AC usage. Ten 400 watt panels = 4000 watts x 80% = 3200 watts x 5 hours = 16000 watts divided by 12.5 volts = 1280 amp hours. In theory, it would work but there are things missing from my numbers - like conversion losses and the fact that you can't get ten panels on a 40' DP (I can't - three - maybe four is the limit) - maybe a big 5er is different. Fun exercise though!! :-)

[NomadBD]

Also, it would not be portable. For example, an average 35 to 40 watt solar panel is approximately 3 foot x 3 foot.

[JFNM]

I certainly would not attempt it with panels like that! :-)

My 327 watt Sunpower E20 panels are 41 lbs each and measure 42" x 62". I understand that there are now some 450 watt panels of similar size/weight. Nonetheless; a LOT of space would be required!

[halfwright]

Not practical--maybe doable. You can buy a generator and a lot of fuel for what it would cost for a system like that. Or pay for hookups.

[vsheetz]

Doable maybe, given enough money and physical space for panels. However unlikely realistic or economical.

[RVGuy1966]

I guess another ten years of solar technology coupled with technology leaps in the air conditioning and heating field may just get us to a portable solar unit that would operate and charge during the day and then off high output lightweight batteries.

ah the future!!!!

[JFNM]

Indeed!! All sorts of exciting possibilities! A nuclear reactor the size of a pack of cards that we each carry around to power our car, airplane, rv, house, etc.... wireless electricity that is satellite based so we're connected no matter where we are, and... ?????

:-)

[kenn_chan]

My TT is full solar and I can run my AC for about 3 hours with no solar input before I hit the 50% threshold on my batteries. or about 5 hours give or take during the optimum harveting time frame.

My TT is small 16 foot box 19 foot total length and the AC unit is called a spot ac which means it is a really small compact ac unit it only uses 800 watts when running and is as near as I can calculate (from the metric measurements) about a 4000BTU unit. system is as follows:

240 watt Q cell panels x 2
220 Ah AGM x 2
tristarr MPPT45 charge controller with remote temp etc.
magnum 2012 inverter charger with remote temps etc.
bogart trimetric battery monitor
all wireing is pure copper with sizes calculated for less than 1% voltage drop total.


things that help this work: my solar panels cover 95% of my flat roof and I have 6" of clearance form the roof when they are flat, when the are tilted both panels are on an aluminium frame that moves both at the same time, so no shading, and less heat into the roof to start, camper is white helps reflect heat and all walls are insulated with high r factor foam (european style 4 season camper), I have a fantastic vent that I open with the fan shut off to allow heat to escape up

Now in all honesty I usually run the A/C for an hour upon our return to cool off the interior then I shut it down. But I ran it off of batteries once just for $h(ts and giggles for about 5 hours before It got low enough that I shut it down, as I still needed enough electricity to run the fridges until the next day.

I also carry a 2000w yamaha inverter genset for emergencies that I could run it off of while fuel lasts

total investment was reasonable as I bought the solar panels and batteries used when they were 6 months old from a disaster relief org that used them during the fukushima earthquake the TS45MPPT, the bogart trimetric, and the magnum 2012 were all bought new via amazon but I got good deals on them through careful shopping when they were individually on sale or discounted system design, install and execution were all done by yours truly as a project ot keep me busy on the weekends so besides the savings in labor I was not able to consume my normal capacity in beer there by saving even more money

[Biken201]

Very cool... More pics please.


- 2011 Ram 3500 DRW
- 2014 Arctic Fox 31D

[kenn_chan]

First thanks to Handy Bob for inspiration, and validation of my own concerns. His thoughts IRT wiring and location of items is spot on, though we differ IRT MPPT controllers, though we are identical in all other areas.

weather is kind of bad, but here is a photo of a (spot aircon) small japanese portable A/C that is similiar to what I installed.

copy and paste this into your search engine for other models photos

スポットエアコン

there are many sizes and shapes/BTU levels available so you are only limnited by your imagination as to how to install.

the actual BTU's i reported earlier might be different, I reported like 4k, but I think mine is actually 6k after after recalculating the calories against btu's it seams the wattage is strictly for the compressor/fan so if you go by wattage used vice calories it gets skewed.

the unit are very efficient as they use the same motor to turn both of the fans, the one on the evaporator and the condenser saving electricity in the process. when I installed mine I made dividers that shunt the hot air out through the original vents for the 3way fridge (since deleted and replaced with two Engel 12 volt units) so basically the A/C was molded into the same location as a standard 70 liter 3way dometic

Actually the a/c was smaller and it is very basic. Hi and Low but for me I run it on high for one hour and then if its reallly nasty I run it on low from then on high is 800 watts at 100 volts 50/60 htz and low is 650 watts at 100 volts 50/60 htz. it really like the 60 htz over the 50 htz and when you run it on 115 it really moves the air well (japan is a nominal 100 volts and either 50 or 60 htz depending upon location. I use a MS2012 so the power output is 115@60 htz which the A/C works fine on.

the second photo is someone ducting the cold air into a large van commonly converted to a camper. I just ducted the hot air out and framed the unit under the cabinets. my water drain is through a hole I drilled through the floor and then caulked and sealed around the drain tube. so the condensation runs straight down and out.

I will get more photos over the next couple of days if you would like, just tell me what you want to see.

cheers