Sunday November 11, 2012:  Updated November 18, 2012

Two Years of Solar Power

It's been 2 years since I first installed solar panels on the house and tied them to the electric grid.  During that time, the panels have produced 18333 kWh (kilowatt-hours) or about $1830 worth of electricity and prevented about $1800 in gasoline from being consumed, (had I not been driving an electric pickup truck for the last 14 months).  In addition to collecting all that free energy from the sun, the solar panels have prevented 37508 lbs of CO2 from being released into the atmosphere (through electricity that would otherwise be generated at the power plant), plus another 9500 lbs of CO2 from the gasoline that was not burnt by not driving a gas vehicle.  

Our solar panels were originally sized to cover 90% of the home's electric needs.  Due to recent efficiency improvements that we have made in the home, the solar panels on our house roof now produce all the energy our family needs, except for heating and energy for our second vehicle - which still runs on gas. 

2 years ago today (11/11/2010), the power meter on the house was swapped out with a net-metering one and reset to 000000 kWh.  One year later (11/11/2011), it read 000980 kWh.  Between the house and driving the EV truck, the power meter reading climbed as high as 002130 kWh in Feb 2012.  Today (11/11/2012), nine months later, it reads only 001705 kWh.  

Efficiency improvements have chipped away at our home and transportation energy needs.  We are well on our way to having the power company's net-meter on the house once again read all zeros, by early 2014 or sooner.  

What happens if we continue making efficiency improvements?
If we have too much power, I will just find other ways to use it, saving energy/money in other areas.  
  • Stop buying gasoline and become a 2-electric vehicle household
  • Use an electric furnace or heat pump instead of a natural gas one
  • Make some hydrogen
  • Go back in time ;) 

Besides, I'm not in the business of selling energy.  It is far more valuable for me to use it than to sell it back to the power company for 1/4th the price.  

In 2010, our total household and transportation energy needs were 63200 kWh.  
Previous usage -- 5000 sq-ft House (2010): 
Electricity - 12000 kWh (1000kWh/month)
Natural Gas - 24900 kWh (850 therms/year   1 therm = 29.3 kWh). 
Gasoline -- 26300 kWh (720 gallons per year for 2 vehicles)
Total energy use =63200 kWh = 63.2 Megawatt-hours

Today, (11/2012) our total energy usage is 37800 kWh per year, 40% less than it was 2 years ago.  
Current usage -- 5000 sq-ft House (2012): 
Electricity - 9800 kWh (includes driving 11000 miles in the EV truck)
Natural Gas - 18300 kWh (624 therms per year)
Gasoline -- 9800 kWh (268 gallons per year for remaining ICE vehicle)
Total energy use =37900 kWh = 37.9 Megawatt-hours

In 3 more years and after we make a few more planned improvements, I project our usage will be low enough that being 100% solar powered is a very realistic scenario.  

Projected usage -- 5000 sq-ft House (goal for 2015): 
Electricity - 5300 kWh (including driving 18000 EV miles)
Heating/Hot Water - 10500 kWh
Geo EV -- 1680 kWh (12000 miles -- 140 watt-hours per mile)
EV#2 -- 1650 kWh (6000 miles -- 275 watt-hours per mile)
Total energy use =15800 kWh = 15.8 Megawatt-hours

I would still have to install 4 more kilowatts of solar panels, (for a total of 10.2 kW which is all that will fit), on the house roof to run everything. 

I have come to the conclusion that with an efficient enough home, vehicles and appliances, a moderately sized solar array can supply all the energy requirements of that home.  Heating, cooling, lighting, appliances, hot water, washer/dryer, 2 freeway capable electric cars, home theater, all powered from sunlight collected in your own backyard.  All without sacrificing any modern conveniences or making any major lifestyle changes.  How cool would that be?  I hope to find out real soon.