Monday, 4 June 2012

Binky Goes Off-Grid

Binky, an old friend of mine who lives in a nice wooden cabin on a farm, contacted me recently needing help putting together her off-grid alternative energy system. Now for many people having an alternative energy system has become the latest middle class hobby to save the planet (said tongue-in-cheek). But for Binky it's essential as she has no mains electricity. I went down to see her and she presented me with a:

* 6 amp solar panel (from the USA but can't remember the manufacturer)

* a very fancy all singing, all dancing charge controller unit (Schneider C40) to prevent overcharging

* an amazing bank of industrial 70 Amp hour nicad cells that was she purchased secondhand (Alcad LC-70). The nicad battery consists of 10 x 1.2 volt cells linked together to provide 12 volts.

* a small cheapie (but very useful) multimeter to check the voltage of the battery.

My brief was to put it all together in a safe and efficient manner. For a start the voltage of the system is 12 volts, which means thick cabling as there is potentially high currents involved and to avoid power losses. Luckily Binky is quite a low power user. She mainly wishes to power a small DAB** digital radio and a lighting circuit, but with plenty of room for future expansion. Fuses need to be added and a meaty diode in-line with the solar panel to prevent power feeding back down.

"Mains" style switch/fuse boxes was used with 13 amp fuses, between the battery, charge controller and solar panel. Used "cooker" cable to wire it all up. All the connections are through a large "choc" block, which also supports the diode. All of this was bolted onto a wooden panel to be mounted on the wall. At the moment all power distribution is via automotive "cigar lighter" connectors. Not the best connectors in the world, but useful for now.

As the system evolves I will update you all on its progress.

Best wishes from Dave the Pixie

**Digital Audio Broadcasting