diy solar

diy solar

Tow vehicle and trailer set up

FJimmy

New Member
Joined
Nov 29, 2021
Messages
12
Hi all,
I'm preparing the solar power set up for my tow vehicle and camper trailer for a trip around Australia. We will be gone for a year, maybe more. Here are the requirements I've come up with:


Power usage
Car
Amp/hrRun timeUse in 24hr
Fridge
2​
24​
48​
Van
Laptop J
1​
12​
12​
~5amp battery
Laptop A
1​
5​
5​
CPAP
1​
8​
8​
7w=airsense10 hum off, temp off. Airmini=6.3W, hum on
Lighting - bulb
0.3​
5​
3​
ea
Lighting - strip
1​
5​
1​
ea
Pumps
2​
Fridge
0​
run on gas
Phones
4​
33​
Total
83​

* these are rough over-estimates
** I'd like to have 3 days capacity in case of inclement weather
*** there will be times when the car and van are detached e.g. unhitching the trailer to drive to a more remote location and camp in a tent for a few days. Or leaving the trailer at a campsite and driving somewhere else for the day.
**** the list is missing a few things like a 12v kettle, batteries for tools (occasional) etc.

Questions:
1. Are my calculations realistic? I'll be working and studying while on the road, while my girlfriend will be working part-time.
2. How should I spread the batteries? 200ah in the car, 100ah in the trailer?
3. I think I need to build two fully independent systems, but is there a more efficient way to do this rather than building two of everything? The trailer has much more roof for solar, while the car has an alternator. So while camping for a few days the lack of solar for the car's second battery is OK as it has a much larger capacity and is charged relatively quickly with the alternator, while the trailer has ample solar power for the smaller battery? Can i put say, 600W solar on the roof and charge both batteries while stationary, while the alternator charges the two batteries in the car and the (excessive) solar on the trailer charges that battery rather quickly?
4. OR should I just bite the bullet and have two DC-DC MPPT chargers, two 200ah banks, two 400W sets of solar panels (a combination of foldable and roof-mounted panels for the car due to space). I'll likely need to upgrade the alternator to a higher output unit. Yes, saving 12kg by having a 100ah battery is important, but having my electrical needs covered is more important.

Hope this post reads clearly, even though I'm confused!
Thank you.
 
I'd keep all batteries in the trailer, all solar on the roof of the trailer, and run a proper sized set of wires / connections between the car and trailer to charge the battery bank when driving.

Running laptops etc in the car shouldn't be a problem while driving. When stopped I'd spend the time in the trailer. If you plan on sitting in the car for prolonged times while not driving, I'd add another 2 wires to run power from the trailer to the car.

I'd not mess around with 2 systems, let alone foldable solar panels. Get as much solar on your trailer as possible. On a proper aluminum strut rack that goes over low fans, or install any fans in the side walls. Use commercial grade full size 400 to 600 watt solar panels, not this 100 / 200 watt made in China junk from Amazon.

I'd build a 280 Ah LifePo battery, that will cover your requirements nicely with room for more.
 
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OK, so that means I'm 100% reliant on the trailer for power. This whole time I thought I needed to have power in the car as well but thinking about it... we are not going to take an extra tent and all that jazz that we would need to camp without the trailer. There's just not enough room to justify taking all of the additional gear that the trailer already has. Therefore, the only reason we would need a second battery is to power the fridge for day trips. So you are right - its a lot of work for not a great deal. Never realised that; thank you.

"On a proper aluminum strut rack that goes over low fans, or install any fans in the side walls"

Are you suggesting fans mounted externally, on the roof, to blow air onto the panels to cool them down? Do you have a picture?
 
OK, so that means I'm 100% reliant on the trailer for power. This whole time I thought I needed to have power in the car as well but thinking about it... we are not going to take an extra tent and all that jazz that we would need to camp without the trailer. There's just not enough room to justify taking all of the additional gear that the trailer already has. Therefore, the only reason we would need a second battery is to power the fridge for day trips. So you are right - its a lot of work for not a great deal. Never realised that; thank you.



Are you suggesting fans mounted externally, on the roof, to blow air onto the panels to cool them down? Do you have a picture?

No, just in case you are going to install any fans for the trailer in order to keep hot air out when you sleep / live in the trailer. Most folks install rather tall fans on the roof and they take away room for solar panels, often forcing them to use these shitty 100 / 200 watt crapshots from Amazon.

So if you need fans for the trailer, rather install a couple on the sidewalls, keeping your roof free of obstructions.
 
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