Hello! I’m hoping to rig up an off grid solar setup, something that can be mounted on my SUV, with enough juice to charge small USB devices, LED string lights, as well as a small pond pump and brushless fan for a DIY swamp cooler. I’m looking for help on design of the circuit and choice of components as this is a new area to me. Also need to source parts, looking for second hand to keep costs down. I’ll be in a high sun environment
Fun project!
There was an article on hacker news a couple days ago about a cheap simple solar setup. The author used it on his apartment, but I think the setup is actually more suitable for an SUV/RV.
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I installed a 265 W panel on my RV - the panel is about 1 m x 1.4 m, so might be easier to pack instead of mount.
Picked it up at Amray in Burnaby for $0.85/Watt and if you look you could probably find cheaper. This was the smallest panel they had. Amazon was around $1.75-$2.00/W, Costco, Canadian Tire etc were all expensive “retail” prices. Craigslist has a lot of people asking unrealistic prices but you might get lucky or find something smaller that fits better.
I used a $20 made in China PWM controller from Amazon that will charge a 12V or 24V lead acid battery, lets you adjust some charging voltages and has a couple of USB outlets. MPPT is more efficient but pricier - it may be better to put the money into another panel. Watch out for cheap MPPT on eBay/Amazon that are just cheap PWM controllers with MPPT written on them.
You will need a battery or three depending on how much reserve you want. I would get a new deep cycle from Costco or Walmart, a size 27 or 31 would be good. Old car batteries if $ is tight but they won’t work as well and they’ll get trashed by deep discharge. Don’t forget your vehicle has an alternator: start the engine, hookup some jumper cables and you have backup power/charging if you don’t have a generator.
An inverter is nice if you want AC power. Modified sine waves are cheap, but may cause issues with some equipment. I have a 1500 W modified sine wave and it runs the microwave and fridge just fine.
With two 27DCs and the panel I kept the fridge going for four days. Had some cloudy days so had to run the engine a couple of times. At the end of it the batteries were pretty drained. I may need to tweak or upgrade the controller, or put in another battery. As far as hacking goes I’m looking at some MPPT type circuits.
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I was going to say, but wait you can get the panels on sale from CT, but you
are right, they are STILL pretty expensive even at 50 to 60% discount.
A couple years backup I got 2x 100w Coleman Panels from CT and in 2014 and
2015 each got 3 of the Coleman 40w panels.
The latter were on sale for about $110 while former was on sale for about
$300 or $350. Late last year I was at Polar Batteries on Boundary and they
have a 250W or maybe 350W for about the $0.85/w that John Paul quoted and it
was a big name brand too.
Nothwithstanding the above, the 40W panels are pretty handy as they have a
folding stand and CT also carried the Coleman Solar Hub
http://www.canadiantire.ca/en/pdp/coleman-8-in-1-solar-panel-hub-0112045p.html
Which allows you to plug up to 8 panels in for more juice. Though that also
means a heftier charge controller. The ones that come with the 40W panels
are 7amp capable.
On the flip side good quality MPPT charge controllers seem to be in the $150
to $450 range…
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