BIT Studio

May 9, 2016

Solar Office

Filed under: Solar — webmaster @ 11:10 pm

  The Armageddon-Lite Project was conceived after the December 2013 power failure in Toronto. We were without heat for three days in subzero weather and we decided that if we had had heat, life would have been (relatively) comfortable. Our furnace is a natural gas boiler-radiator system that requires 460 watts of electricity to drive the PLC, circulating pump, and exhaust fan. I put together specifications for a solar-driven battery backup system to run our furnace, freezer, iPhones and iPads in the case of a prolonged power failure.

Our current electrical backup system has five solar panels (500 watts), two 100Ah deep cycle 12 volt batteries, one 1000 watt pure sine wave AC inverter, one 1200 watt gas generator, and one 12 amp 120VAC-to-12VDC inverter. The panels typically generate 8 amps of power in medium sunlight, which means that in Canada (three or four hours of direct sunlight per day), the system can generate about 25 amp-hours of electricity per day. In emergencies, the system is capable of running the furnace on solar power through the daylight hours. At night, two or three hours of gas generator operation top-up the batteries sufficiently to run the furnace through the night.

The original non-emergency version of Armageddon-Lite operation was fairly simple. My intent was to power a mini-fridge (230 watts) and mini-freezer (240 watts) every day. While the off-grid system was adequate for powering the fridge and freezer in daylight hours, the 24/7 nature of the appliances required grid-powered battery charging for four hours per night to charge and maintain the battery level. Although operationally successful, it was a lot of work to monitor and sustain.

So… the current state of Armageddon-Lite, non-emergency mode, is powering my home office. I turn on the 1000 watt inverter in the morning and this powers my computer, three lights, a single-cup coffeemaker (yay!), and minor office peripherals throughout the day. Also, on most days I am able to plug my hot water tank into the system. The office and water heater draw less power than the solar panels provide and at the end of the day, the batteries are fully charged (i.e. over 13 volts) and ready for the next day’s use.

The Armageddon-Lite Project is an evolving work-in-progress. Our next step involves the addition of one more deep cycle battery to increase the capacity of evening storage. The new hardware will connect easily to the existing framework and provide sufficient capacity to run the home office, the mini-fridge, and the mini-freezer without requiring nighttime inverter-to-battery support from the grid.

It is not much, but it keeps us prepared for the next power outage and maintains a small portion of the house as officially “off-grid.” Fun stuff!


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