Oliver – Solar Panel Ponderings

One of the biggest challenges to living a solar powered technomadic life in a trailer as small as the Oliver is the lack of roof space to mount solar panels.

The Oliver’s fiberglass roof isn’t just small, it is not even flat. It rises up in the middle to allow for interior headroom, and it is lower on the sides.

By removing the satellite TV antenna, and by having the factory slide the roof fan back towards the air conditioner, and the bathroom fan forward a bit – the flat area left for potential solar goodness is around 61″ x 28″, give or take a bit. (Without relocating the vents, there is around 34″ length…)

I’ve been researching a few potential panels that may potentially prove workable:

• Kyocera KC-65T: 65W, 17.4 V peak power, 21.7 V open circuit.
  29.6″ x 25.7″ x 2.1″ x 13.2 lbs — $350 ($5.38/watt)
• Kyocera KC85TS: 85W, 17.4 V peak power, 21.7 V open circuit.
  39.6″ x 25.7″ x 24 lbs — $438 ($5.15/watt)
• AM Solar AM100: 100W, 21.5 V peak power, 27 V open circuit.
  57.25″ x 21.25″ x 1.92″ x 20.8 lbs — $550 ($5.50/watt)
• Kyocera KD135GX-LP: 135W, 17.7 V peak power, 22.1 V open circuit.
  59.1″ x 26.3″ x 1.4″ x 28.7 lbs — $655 ($5.04/watt)
• Mitsubishi PV-MF170EB3: 170W, 24.6 V peak power, 30.6 V open circuit.
  62.2″ x 31.5″ x 1.8″ x 32.2 lbs — $761 ($4.48/watt)
• Sharp NT-180U1: 180W, 36.86 V peak power, 44.8 V open circuit.
  62″ x 32.5″ x 1.8″ x 37.5 lbs — $905 ($5.03/watt)

Technical Note: Typically, to interface with 12V batteries, you want solar panels with around 17V peak charging voltage. To use panels with a higher charging voltage, you need a MPPT charge controller to down-convert the panel voltage. I am considering potentially using a higher voltage panel because I am leaning towards an MPPT capable charge controller.

Mounting Hardware:
The next challenge is the mounting hardware. Flat mounts are simpler, but tilting mounts give you the option of pointing the panels towards the sun while parked, which can give you a substantial boost in power. But they also then require you to figure out a way to get up on the roof to do the tilting….

Northern Arizona Wind & Sun has a page full of various RV mounts to consider.

The AM Solar folks have a nice set of RV-optimized mounts with tilt bars here. These mounts seem particularly well suited for roofs that are not perfectly flat.

Multiple Panel Options:
The AM Solar folks have been talking with the Oliver plant manager, and they think they have come up with a way to join two AM100 panels together sharing a single set of tilting mounts. This will result in 42.5″ of width, with around 5″ of wing-like overhang to either side of the Oliver’s hump. Hmmm….

The other option for multiple panels would involve having a second deployable panel that we only set up while parked for extended periods. The second panel could be set up freestanding at the end of a long wire so that it could be put in the sun while we are parked in the shade, or perhaps it could be mounted as a shade over the rear window like this ingenious Casita modification.

With either of these options storage and setup becomes a chore, but the extra capacity for living off-grid may prove worth it.

Concluding Thoughts:
The Kyocera 65W panel looks like it will fit in the area where the satellite dish sits on current Olivers, without the need for relocated vents in the roof. This is probably the best option for current Oliver owners looking to upgrade to solar.

Starting from scratch, I am torn between the 2x AM Solar option, or trying to squeeze a single larger panel on like the 180W Sharp. The 135W Kyocera is probably the largest panel that will fit on the roof without any overhang.