Wednesday, April 22, 2015

When You're Serious About Solar For Your Off Grid Home On Wheels...

The Colorado based owner of this once upon a time 1990 Chevrolet school bus was determined to create a vehicle to live in for extended periods of time off grid. It looks like he succeeded.
The fourteen German Sun brand 130 watt panels that are tilted manually, feed eighteen 105amphour Trojan batteries. All that combines with an Outback brand control system.
There's more about this bus here.
With solar, there's no such thing as overkill...


  1. A T105 weighs 62 lbs or 28 kg, a little over half a US ton of batteries.
    A school bus can handle it.

  2. Sorry Keith, but I have to disagree with your closing statement. There really ~is~ such a thing as "too much" when considering battery storage in a solar power system.

    From all appearances, and by calculating the battery voltages and comparing with the brand of processing equipment chosen, I believe that the bus builder has attempted to take the 18 T105 batteries and combine them in a series-parallel string to create 1620 ampere-hours of storage at 12 volts. They are attempting to do this by parallel connecting 9 strings of 12 volt batteries (two 6 volt T105's in series)

    What the bus builder (or it's new owner) is going to find out over time is that the 9 parallel stings are going to become out of equalization. Some of the strings will be charged properly, while others will suffer a chronic under-charge condition. This will quickly kill the under-charged batteries due to sulfation of the cells.

    It is a hard and fast rule in battery-based renewable energy systems that no more than two paralleled series strings be used to increase the ampere-hour capacity of the bank. Two strings will stay in fairly good equalization, but the preferred method is to use only one battery string and increase the system voltage to lower the total current drawn by loads, effectively multiplying the ampere-hour capacity of the bank.

    If the builder had instead designed a 48 volt system with eight Trojan L16 350 ampere-hour 6 volt batteries, essentially the same amount of energy storage would be realized without the attendant imminent battery death lurking around the corner. He could have also saved some money and used a single FX80 charge controller instead of the dual controllers pictured.

    As the depicted vehicle appears to be a survivalist "bug out" shelter, it probably matters very little how well (or poorly) the batteries get on. After the first volley of shooting, there would be so many holes in both the bus and the PV's that I doubt that battery life would matter much in the long run.

    1. I accept your more indepth knowledge on the matter Mr S and thankyou...

    2. I'll be pulling up to your place with my 1986 Toyota Escaper for some solar panel wisdom, Mr. Sharkey, right after I re-coat the roof.

  3. Mr S sounds like an electrical engineer maybe.

  4. We have two big solar panel attached to our touring caravan roof. It provides all the power we need, runs tv etc, recharges 'his' power drills, and keeps our phones charged up, and my laptop too. We can live permanently off grid. It's great.