BIT Studio

February 10, 2014

Solar Panels

Filed under: Solar — webmaster @ 7:18 am

  The winter storm of 2013 in Toronto inspired some green(ish) off-grid thinking. We were without electricity for three days and although it was certainly an inconvenience, things could have been much worse. On day 3, just before the power came back on, the house temperature had dropped to 13 deg C (candles kept us going) and we were ready for a hotel. We decided that if we had had the basics of 1) heat, 2) food and 3) communication, we could have lasted a long time.

A hybrid solution of solar panels and batteries combined with a small back-up generator could accommodate our requirements. The system would need a sustainable infrastructure that would be always running and emergency-ready. For heat, the house has a natural gas furnace (radiator) that requires about 450 watts (3.5 amps) to power the exhaust fan, water pump and electronic ignition. For food, a small Danby fridge draws close to 200 watts (1.6 amps) and fondue pots (as we found out!) are incredibly efficient cooking devices. For communication, cell phones and tablets draw little electricity but still require a pure sine wave power source to charge safely.

Proposal:
-165 watt solar panel array
-2 battery charge controllers (DC to DC, 7 amp)
-2 batteries (12V DC, 100Ah, deep cycle, sealed)
-1 inverter (DC to AC, pure sine wave, 1000 watt)
-1 generator (gas powered, 1000 watt – for emergency only)
-1 battery charger (25 amp, AC to DC – for emergency only)

The system is designed around a 1000-watt power requirement. Small fridges and freezers consume approximately 250 Kwh per year (700 watts per day) and the above solar panel system should be able to sustain the daily operation of one mini-fridge and one mini-freezer throughout the year.

In the event of a power failure, the freezer would be unplugged from the system and the furnace would be plugged in. The additional power usage requirement (freezer at 200 watts versus furnace at 450 watts) would be met with a small 1000-watt gas-powered generator. Running the generator for one hour every evening would top up the batteries as required. The gas water heater and freezer could be plugged into the generator. The daily one-hour operation should provide sufficient energy 1) for hot/warm water throughout the day and 2) to maintain the freezer at an adequately low temperature for quite some time.

Once installed, the system should be very low maintenance. The batteries are sealed and under the proposed conditions should last for at least three years. The switchover from standard to emergency mode requires moving three plugs (furnace, freezer and water heater). Running the generator would be for emergencies only and with a bit of luck, it may never see any action.

And that is the idea. Now for the implementation…

 

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