Alpine Hut Solar Lighting

Photos: https://photos.app.goo.gl/BCGs3RD6exFYfUag9

Technical details

A 100W poly-crystalline panel supplies some electricity even in the dead of winter when days are short and a mountain blocks the direct sunlight. Poly-crystalline panels work better in weak light.
The panel charges ten D size NiCd batteries “Fufly” in series which can hold ten ampere hours.
Current limiters limit the charging current to 0.5 ampere, so the batteries will charge completely in 20 hours of sufficiently intense light.
Two small light emitting diode lights each draw 0.25 amperes so they will completely empty the fully charged battery in 20 hours. One hour of diffuse sunlight will give us one hour of led light, or two hours if only one light is turned on. Mirrors behind the lights make it seem as though there are twice as many lights.
The two lights are switched off after one hour, by clockwork timers. Each light has its own timer.
We do not know for sure if the diffuse winter sunlight will provide one hour of light for one hour of daylight but this seems likely. We do not know if the current limiters will protect the battery from over-charge, but this seems likely. We have to wait for winter to see how successful we have been.

Roland Burton put it all together in Vancouver and to simulate winter conditions at our hut, mounted the panel facing north. Even on cloudy days we could get 5 watts out of the 100 watt panel.

We carried it the five kms up to Phelix hut on the weekend of June 12-13th 2021 and it took about a day to hang the panel, install wiring, lights, switches, and test it all. There was about a meter of snow around the hut and the lake beside the hut was still 80% frozen.

Total cost was ~$450 covered by the UBC AMS Sustainability Fund. Thank you!

All four of the Varsity Outdoor Club's huts have solar lighting now!