Station Wagon Solar Roof and Solar Sub- Self Sufficient Sonic Splendor
Toyota has been advertising the “Solar Roof” option for the new 2010 Prius- it’s basically a solar module integrated into the roof panel that runs the cabin ventilation fan on hot and sunny days. Simple enough- but what they didn’t tell you is that you can have a solar roof on any car- obviously!
I set this system up for my Northwest roadtrip, as previously described. It worked like a charm, supplying me with laptop charge and ample stereo bass all 2300 miles of my trip. What’s this about subs and bass exactly?
One of the prime objectives of the system was to power up my subwoofer system- because what’s a roadtrip without a subwoofer? You may be thinking to yourself, WTF? So let’s get this straight. I mounted an 80watt polycrystaline PV panel to the roof of my station wagon. I ran the power to a charge controller and 90AH SLA battery pack behind the drivers seat. And with the resulting charge I ran a small inverter and a subwoofer amplifier.
'90s Japanese midsize wagons aplenty
Simple enough- and in all seriousness, it worked really well. Here’s the details:
The module is an 80 watt Photowatt module I purchased several years ago and borrowed from my roof.
It’s anchored to the Camry’s factory-installed roof rails by way of 2×2 lumber, U bolts and plastic tube
Note to self- beware that the distance between the rails on the Camry gets bigger toward the front of the car!
12GA landscape-lighting cable is run in through the rear hatch- I’ve found that landscape lighting cable is widely avaiable and not too expensive, as well as water and sunlight resistant.
The cable is run forward to the driver side rear footwell
From there, the charge controller and batteries are hooked up, as well as the loads.
I used the parts I had on hand- 2x tired old PowerSonic batteries, a BZ Products M20 charge controller. The terminals are insulated with tape, I neglected to add fuses aside from the charge controller’s internal fuses- not a good idea, but I was lucky and was spared any disasters during my trip.
A small mod-sine inverter was sufficient to charge my laptop while I was camping. I made its leads long enough to move around the front seat area.
I put the sub amp under the passenger seat
And used this sweet pushbutton I scavenged from an old junked BMW to activate the amp
There you have it- for two weeks this system kept me supplied with charging power and sweet tunes. It was a no-brainer project for me since I already had all the equipment, but I could see something like this being very worthwile for the avid car-camper. It’s like how many RV people put up solar panels- why should they have all the fun?
If you’re interested in putting something like this together, there are a million different ways you could go about it- roof racks, solar panels, charge controllers, batteries- but here are some ideas of where to start.
PV Panels:
- Something like these is likely one of the easiest options- I have on occasion seen other panels of this sort for sale, all in one chargers with built in charge control. Not the most cost effective though.
- Traditional-style PV panels can be purchased from many dealers- this is one of my favorites. Chose a panel for output and dimensions.
- For permanent installation, particularly on lower-roofline vehicles like my Wagon (as opposed to a van) a glass-less panel may be a good investment to avoid the worry of vandalism or accidental breakage. Unfortunately the best choice, larger Uni-Solar modules appear to have been discontinued and are very hard to find.
Charge Controller
- If you found a panel with integrated charge control, you’re good to go. Similarly, if you’re using a tiny <10watt panel you are also OK- otherwise you’ll need a charge controller to keep your battery pack from getting roasted.
- A controller like this one will be suitable for panels up to around 80 watts. It also includes an LVD output that you can use to power small loads while protecting the battery from being entirely drained.
- This one can make for a very tidy installation as it mounts directly on the panel’s junction box- just beware that some small panels don’t use J-boxes.
- There are many other options. These cited in particular are just my recommendations.
Battery pack
- In order to use a battery in your car you really must use a sealed lead battery as opposed to a flooded one typically available at autopart and warehouse stores. Unfortunately these are much more expensive and pickier, but you don’t want to risk the explosive fumes collecting in your closed car that result from charging a flooded battery, as well as the danger of liquid sulfuric acid.
- You can check out Northern Arizona Wind and Sun’s selection here, or shop around. It can be worthwile to shop locally as battery shipping is often expensive due to their weight. 60+ Amp Hours will give you the best flexibility.
- Something like this is a nice option but quite expensive.
Make sure all your wires are appropriately sized (12GA min, 10 or 8GA OK) and that you use ample fusing. For systems this small an inline ATC fuseholder is generally sufficient. “Car Stereo” style fuseholders are also a good option, also easy to find locally and with higher current capacity. There is some benefit to using a fuse block, but this is one of the areas where it is easy to quickly stray from the KISS (keep it simple stupid) ideal of the project.
If you crimp terminals crimp them tight- you should be able to break the wire before it comes out of the crimp. Landscape lighting wire and ATC fuseholders/fuses can be found at your local hardware store. It’s no problem to attach an inverter to the system, or a cigarette lighter receptacle (auto parts store) for other types of chargers. A 30 amp system fuse will support a 350 watt load.
Hope you find this interesting or inspiring. I sure appreciated my purely solar powered sub tones all the way up and down the West Coast.
In: Life and Times, Little Fixes, Renewable Energy System