# Ideas for a Van Solar System



## MoonRiver (Sep 2, 2007)

I have a small travel trailer which has a 100 watt panel on the roof and another 100 watt panel that I can hook up if needed. I used 2 y cables, so that if I need the 2nd panel, I just plug it into existing system. It is all I need for lights, fan, electronics charging, water pump.

So I was thinking it would be nice to be able to run (not all at the same time) the microwave, the refrigerator (can run on ac, dc, or propane), and a 5000 BTU air conditioner. The AC would only be used a few hours a day.

I don't have any roof space left on trailer, so I was thinking about getting a van for my tow vehicle, and putting the panels on its roof. Just guessing, I need at a minimum 600 watts of panels. 

I see the van as a mobile generator. It would have a power cord that I could hook the trailer up to similar to hooking up to shore power in a campground or a regular generator. Or if I needed power somewhere on my property, I could just drive the van there and have power available.

I think starting with 2 panels would be good with option to adding 1 or 2 more. So if I went with panels between 250 w and 300 w, the range of installed panels might be anywhere from 500 w to 1200 w. I think going with lithium batteries would be the best option for batteries.

How would you go about doing this? I know most of you can design this off the top of your head, so hoping you can help me get this jump started.


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## wy_white_wolf (Oct 14, 2004)

AC a few hours a day is going to take closer to 5KW array instead of the 600 you're thinking. You really need to start with doing a full analysis of your loads and how much power you will be using. 

WWW


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## MoonRiver (Sep 2, 2007)

wy_white_wolf said:


> AC a few hours a day is going to take closer to 5KW array instead of the 600 you're thinking. You really need to start with doing a full analysis of your loads and how much power you will be using.
> 
> WWW


Here's my thinking. Tell me where I went wrong.

A 5000 BTU AC uses about 500 watts. If I capture 80% of 600 w for 6 hours that's about 480 w/hr x 6 hr or 2880 wh. 2880 divided by 500 is about 5 hr.

I've seen videos of people running a 5000 btu ac with as little as 400 watts of solar panels. The other thing is my trailer is only about 80 sq feet.


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## Offgrid48 (Jul 28, 2016)

You are going to spend a lot of $$ on a lithium battery, don't think it would be cost effective for this application but you are going to need a good battery bank with sufficient amps to cover your load requirements. The panels themselves aren't going to be enough to cover your loads, you need to store the extra needed power in the batteries. Solar panels are never as efficient as you expect. Since you mentioned you are going to use your van as a portable generator, I would recommend adding a 12V charger. I added an 80amp 12v charger so when my generator was running it could charge the batteries much quicker than the solar panels. This seems to work well for my RV setup.


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## Fire-Man (Apr 30, 2005)

MoonRiver said:


> Here's my thinking. Tell me where I went wrong.
> 
> A 5000 BTU AC uses about 500 watts. If I capture 80% of 600 w for 6 hours that's about 480 w/hr x 6 hr or 2880 wh. 2880 divided by 500 is about 5 hr.
> 
> I've seen videos of people running a 5000 btu ac with as little as 400 watts of solar panels. The other thing is my trailer is only about 80 sq feet.


Sure It will work some?? I ran my 5000btu on 320 watts of panels "Some"---they were on a home-made tracker---that helps a lot over stationary----BUT you have got to have a decent battery bank. I used 4 Trojan T105's hooked up 12 volts. The AC would Only be turned on at night and only if the bedroom temp was 80 or above. The AC will not draw 500 watts all the time---only when the compressor is running. I used the energy saver---which would also turn the fan off if the compressor does not cycle on/off. I used this set-up for a few years then bought a lot more solar panels. Get your 600 watts hooked up right---and have a generator for back up. You can even make a manual tracker for the panels---if you are going to be around to adjust a few times a day.


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## MoonRiver (Sep 2, 2007)

Fire-Man said:


> Sure It will work some?? I ran my 5000btu on 320 watts of panels "Some"---they were on a home-made tracker---that helps a lot over stationary----BUT you have got to have a decent battery bank. I used 4 Trojan T105's hooked up 12 volts. The AC would Only be turned on at night and only if the bedroom temp was 80 or above. The AC will not draw 500 watts all the time---only when the compressor is running. I used the energy saver---which would also turn the fan off if the compressor does not cycle on/off. I used this set-up for a few years then bought a lot more solar panels. Get your 600 watts hooked up right---and have a generator for back up. You can even make a manual tracker for the panels---if you are going to be around to adjust a few times a day.


Thanks. Even going to 900 watts of solar panels is not that expensive. But as you mentioned, the batteries are where the cost is. I love to camp at National Parks on Outer Banks, but I have to limit trips to June and earlier and September and later. No generators allowed after 10 pm. While a generator would probably work, I really don't want to lug it around and have to keep filling up a gas can. 

I don't really understand electricity so designing the system will be a challenge. The reason I have trouble understanding electricity is I can't picture it in my head. If electricity actually flowed like water, I could understand it.


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## Fire-Man (Apr 30, 2005)

MoonRiver said:


> Thanks. Even going to 900 watts of solar panels is not that expensive.
> 
> I don't really understand electricity so designing the system will be a challenge. The reason I have trouble understanding electricity is I can't picture it in my head. If electricity actually flowed like water, I could understand it.


 Actually DC voltage is more similar to water---well "hot/+" goes on one side and "cold/netural" on the other. Most DC things do not Like to be hooked up wrong---things blow up etc. Again---get your panels hooked up right---use a generator for back up. Gotta have the battery bank----maybe it will keep the batteries charged but on cloudy days or when ever---if its not charged up---use the generator to charge it---cut the generator off before to late and run off the battery bank through the night.

Understand one thing with solar panels----if its cloudy or dark---they do not charge.


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## MoonRiver (Sep 2, 2007)

Had another thought on this. As I said in OP, my trailer already has 200 watts of solar panels and 2 batteries. What I initially thought of doing was to have solar panels mounted on my van with batteries, hook up an inverter to van batteries and run cable to ac (shore power) input on trailer. Then the air conditioner would run on the supplied power supplied by van batteries through an inverter.

One weakness of this approach was it didn't make use of solar panels and batteries on trailer.

I came up with another approach, but it would take 2 inverters. The above plan of connecting inverter to van batteries and running to trailer would be the same. But now I would connect a 2nd inverter to the trailer batteries and the power coming in from the van would just be used to keep the trailer batteries charged. This increases my solar panel wattage by 200 watts plus 2 additional batteries for the cost on an inverter. I think this would give me about 1 more hour of air conditioning a day for cost of inverter.


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## ed/La (Feb 26, 2009)

The Honda eu2000 generators are great. Quite, fuel efficient, small,light, and last almost for ever. Cost. About $1000 if you shop around.


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