Solar AC for large van

WaterWheel · September 2016

A neighbor just got a panel van for his work and wants to see if it is feasible to use a solar system to run a small RV type AC unit.

His alternative is using a generator which is noisy, especially since he often works late in residential areas repairing fiber optic cables. I suggested he may get away with 900 watts in panels on the roof, 3-4 large AGM batteries (he wants AGMs) ect. but I suspect he's going to need a 1 ton unit and that's a lot of power, close to 1000 watts when running hard with a super efficient unit which will require a pure sine wave inverter.

Is this doable for under $2800 if he does the work himself?

Photowhit · September 2016

A Honda Eu2000, $900 - $1000 (Sam's Club or Northern Tool) might run a roof air at 1600watts (2000 peak) and is an un-obnoxious noise level.

If it must be done on solar or battery, I'd charge a large enough battery bank for the expected run time from a quality inverter charger. This still might be outside of the $2800 price.

I'd forget the solar. 1000 watts at 24 volts would be 40 amps per hour, 8 hours would be a 24 volt battery bank that could supply 320 amps at near 100% duty cycle. That would be a very good size battery bank.

jonr · September 2016

Super efficient AC units already have an inverter inside them and so don't care about sine wave power (and don't have a startup surge). But yes, use a quiet generator.

WaterWheel · September 2016

I twice suggested a quiet generator as being a more cost effective solution but he's still interested in solar for the van. Any suggestions on equipment? He rolls up to a site and since fiber optic cables are generally in the ground he pulls the cable in his van and splices, sometimes for hours. He's on call 24 hrs a day although usually during the day.

Photowhit · September 2016

I'd say it can't be done for $2800, I air conditioned a small cabin that was particularly well insulated (6" walls), built in the shade. With a small window 5200 BTU unit. It took a 1000 watt array, 4 golf cart batteries, charge controller and a 1800 watt pure sine wave inverter to give me 4-5 hours of cooling. Even at todays cost and picking a cheap inverter. This would cost close to his budget. I'd guess he'll need double the BTU's and more than double the battery bank.

He's basically building a system to do what solar does poorly, provide a high drain load with power. Even my amperage calculations above are on the low side if the since as the battery is drawn down faster than the C20 drain rate their capacity is calculated from...

WaterWheel · September 2016

Without using AGMs does this sound like a pratical and durable system?
Tristar 45 MPPT    $430
900 watts in panels   $950
4 Trojan T-105      $660
wire, fuses, battery box    $150
Samtex PST 200S 2000 watt inverter   $540
total price $2730

I've been using a TriStar 45 MPPT and Samtex inverter for about 5 years on my old system and they are running fine.    My 1st system cost $1895 at today's prices ($1400 back then) and also ran my 5000 btu AC 4-5 hrs a day (chest freezer though the winters) although the AutoZone batteries had to be replaced after 3 years.
I'm not sure how to mount the panels on the van roof and I'd like to see a larger battery bank.      I'm not saying solar is the way to do this but he really wants to give it a try.

Dave Angelini · September 2016

1K$ to 1.5K$ just for the mini-split that I use plus the knowlege and skill to evacuate the line set and install. I would never do this with solar in a van and as reccomended before, certainly not at that price.
If he does not have the money to do it right with solar, he will never have the money to do it over again. Use a generator........

Photowhit · September 2016

WaterWheel said:

Without using AGMs does this sound like a pratical and durable system?
Tristar 45 MPPT    $430
900 watts in panels   $950
4 Trojan T-105      $660
wire, fuses, battery box    $150
Samtex PST 200S 2000 watt inverter   $540
total price $2730

I've been using a TriStar 45 MPPT and Samtex inverter for about 5 years on my old system and they are running fine.    My 1st system cost $1895 at today's prices ($1400 back then) and also ran my 5000 btu AC 4-5 hrs a day (chest freezer though the winters) although the AutoZone batteries had to be replaced after 3 years.
I'm not sure how to mount the panels on the van roof and I'd like to see a larger battery bank.      I'm not saying solar is the way to do this but he really wants to give it a try.

He'll have pretty much, zero insulation, All ready thinks he'll need a larger AC, Will have a comprised angle with solar panels.

Unless there is something you aren't telling us, like he'll only need 2 hours run time...

...It's not practical.

BB. · September 2016

I would suggest renting a Honda eu2000i first (if small AC) and try the ec3000i if the smaller genset does not run the load(s). A Honda eu2000i is running around $1,000 or so right now.

Also, run the loads for 2-4 hours on the genset to make sure it all works well (i.e., things don't overheat/shutdown after 30 minutes).

Other problem with genset is exhaust fumes... Suggest a carbon monoxide detector too inside the van/work area (shifting winds blow exhaust back at work area).

-Bill

WaterWheel · September 2016

Yes, I agree that he will need at least a 1 ton (12,000 btu) system and he knows that will be an additional cost. In addition to cooling the van he often sets a small tent attached to the back of the van to shelter him as he splices the fiber optic cables.

I have strongly suggested a generator, he already has two, but he is still looking at solar and the roughly $2800 price isn't scarring him even after explaining that the batteries have a limited life in the hot van.

At least I can say I tried.

mike95490 · September 2016

Idle the van engine and use the van's AC for cooling ??

Johann · September 2016

mike95490 said:

Idle the van engine and use the van's AC for cooling ??

A very good answer/comment so far. The Van's onboard AC unit as well as many other vehicles with AC units have most likely 1 ton AC units already installed by the manufacturer.

Johann · September 2016

WaterWheel said:

Without using AGMs does this sound like a pratical and durable system?
Tristar 45 MPPT    $430
900 watts in panels   $950
4 Trojan T-105      $660
wire, fuses, battery box    $150
Samtex PST 200S 2000 watt inverter   $540
total price $2730

I've been using a TriStar 45 MPPT and Samtex inverter for about 5 years on my old system and they are running fine.    My 1st system cost $1895 at today's prices ($1400 back then) and also ran my 5000 btu AC 4-5 hrs a day (chest freezer though the winters) although the AutoZone batteries had to be replaced after 3 years.
I'm not sure how to mount the panels on the van roof and I'd like to see a larger battery bank.      I'm not saying solar is the way to do this but he really wants to give it a try.

Do you think, you can get 900 watts of panels on a Van that will power '' maybe '' a 5,000 BTU air-conditioner( less than 1/2 a ton) ?
24 hours on call? The sun will not shine for 24 hours.
Another problem would be that you would need to angle the panels toward the sun to get most power out of the panels. Laying the panels flat on the roof of the van will reduce power output at least most of the day.
Another problem would be where the van needs to be parked when in use. Just a tree branch or a power line that is over head could reduce solar power production a lot. What about shading from buildings or other structures or clouds?

jonathangino · August 2017

Photowhit said:

I'd say it can't be done for $2800, I air conditioned a small cabin that was particularly well insulated (6" walls), built in the shade. With a small window 5200 BTU unit. It took a 1000 watt array, 4 golf cart batteries, charge controller and a 1800 watt pure sine wave inverter to give me 4-5 hours of cooling. Even at todays cost and picking a cheap inverter. This would cost close to his budget. I'd guess he'll need double the BTU's and more than double the battery bank.

He's basically building a system to do what solar does poorly, provide a high drain load with power. Even my amperage calculations above are on the low side if the since as the battery is drawn down faster than the C20 drain rate their capacity is calculated from...

this is what im trying to do, just with 1200 watts solar on a uhaul truck, however im using a 60 amp mppt controller, so i can use only 800 watts. i have a 3000 watt pure sine, 12vdc. i want to run the 500 watt ac unit, also some other smaller stuff, less than 1.2kwh daily otherwise.

i cant figure what batteries to use, though! the one guy says use trojan l16re-2v. another person says use trojan ind9-6v. i like this idea best. otherwise, id like to use li ion, but i cant find them reliable, and cheap...

what do you think? 720 lbs and 40 inches in width are the l16re-2 volt.... also thats 18 caps to check and water! should i look at agm, maybe?? if i could run the AC for a little bit here and there, it would be HUGE. because you know, once its hot in the truck.... forget about it... its gonna be damned hot allllll day, allll night. the AC i would use for maybe a couple hours a day, at most, just to knock down the heat....

any opinions, anyone??

thanks

jonathangino · August 2017

yeah, id run the truck AC, for sure. he can add a oil cooler and maybe another fan to the motor, to keep it cooler. he can also run only syn fluids, and, also try using water wetter in his coolant, for better cooling.

just set a bit of a high idle, maybe use triple chamber mufflers, and use the truck AC! otherwise its alot of headaches....

another way to go is to use some fans, DC fans are most efficient. a couple GC batteries and maybe 300 watts solar would do him fine, for lights and fan usage. if he is in a dry environment, he can use a swamp cooler setup.

Estragon · August 2017

There may be a commercial or other reason to do (look?) solar. I'd put some solar on the roof, put whatever battery fits, add whatever AC is needed, and charge the batteries/run the AC with (an upgraded?) van alternator as needed. Tying the van AC into the ducts probably a good idea too.

littleharbor2 · August 2017

One thing for sure, To use solar panels you need to have them in the sun. If they are on the van, the van has to be in the sun. That's going to be one hot steel box to try to cool with an AC unit, not going to work. At least with the generator you can park in the shade, and not have to be driving a ridiculous looking solar array around on top of the van. Not to mention a half a ton of acid filled, hydrogen spewing batteries.

Estragon · August 2017

> @jonathangino said:
> Photowhit said:
>
>
> I'd say it can't be done for $2800, I air conditioned a small cabin that was particularly well insulated (6" walls), built in the shade. With a small window 5200 BTU unit. It took a 1000 watt array, 4 golf cart batteries, charge controller and a 1800 watt pure sine wave inverter to give me 4-5 hours of cooling. Even at todays cost and picking a cheap inverter. This would cost close to his budget. I'd guess he'll need double the BTU's and more than double the battery bank.
>
> He's basically building a system to do what solar does poorly, provide a high drain load with power. Even my amperage calculations above are on the low side if the since as the battery is drawn down faster than the C20 drain rate their capacity is calculated from...
>
>
>
>
> this is what im trying to do, just with 1200 watts solar on a uhaul truck, however im using a 60 amp mppt controller, so i can use only 800 watts. i have a 3000 watt pure sine, 12vdc. i want to run the 500 watt ac unit, also some other smaller stuff, less than 1.2kwh daily otherwise.
>
> i cant figure what batteries to use, though! the one guy says use trojan l16re-2v. another person says use trojan ind9-6v. i like this idea best. otherwise, id like to use li ion, but i cant find them reliable, and cheap...
>
> what do you think? 720 lbs and 40 inches in width are the l16re-2 volt.... also thats 18 caps to check and water! should i look at agm, maybe?? if i could run the AC for a little bit here and there, it would be HUGE. because you know, once its hot in the truck.... forget about it... its gonna be damned hot allllll day, allll night. the AC i would use for maybe a couple hours a day, at most, just to knock down the heat....
>
> any opinions, anyone??
>
> thanks

3000w is pretty big for a 12v inverter, and will likely use a lot of power just staying lit, and need some big wire to use safely.

I'm not a fan of the trojan l16-2v as they're 3x2v cells in parallel. There are others with larger 2v cells. To me, a 12v bank should ideally have 6 cells, but no more than 12.

If you have shore power or a generator in the truck to charge batteries it cuts down on the size of battery bank you need. If you can be sure of charging every day or second day, a couple of strings of 6v golf cart batteries might work okay.

Solar AC for large van

Comments

Categories