Embracing the future, my wife and I decided to install solar panels on the
roof of our three bedroom house in West Los Angeles. Our successful
self-experiment may be instructive to those with an interest in energy and
Our daily energy production since September,
2010, when the panels were installed. Some days are missed because no one
was home to record the data. The red curve is the expectation from a very
simplified model. The points above the curve were relatively cool days when
the panels were most efficient; low production occurred on cloudy days. The
green points are for the second year. During the first year, our total
annual production was 4150 kilowatt hours.
The first step was to decide how big a system we needed. We
were paying annually about $500 for 4000 kilowatt hours, a typical
residential usage in California for a two-person household. However, there
was a lot of waste. For example, we left the two boxes for the cable TV's on
all the time. Since our son has graduated college, married and is on his
own, we could certainly shut off the cable TV box in his room. Without any
loss of comfort and just a tiny effort -- we still operate a large screen
TV, two laptops and various appliances and gadgets, we have reduced our
usage to about 2700 kilowatt hours/year.
Thinking that we would want to operate an electric car, we
chose a system which provides about 4000 kilowatt hours/year.This required
about 20 square meters of panels -- about 1/8 of the total area of our roof.
The contractor who installed the panel negotiated with the Los Angeles
Department of Water and Power which then directly paid him about $7,000 of
the total cost of nearly $17,500. Our immediate cost was about $10,500, but,
because of the 30% federal income tax credit, our final out-of-pocket cost
was slightly more than $7,000.
We are getting a return on our investment that is hedged
against inflation and vastly superior to the interest we would get by
putting the money in the bank. Installing the panels was a sensible
financial diversification. Our house was built in 1928 and requires upkeep.
The cost of the panels was about the average amount we spend per year on
maintenance and upgrades.
We are of course happy to have gotten the tax credit
installation of panels. For comparison, the $1,000 a year I pay for a
parking permit at UCLA is not subject to federal income tax. Consequently, I
receive a tax subsidy of somewhat more than $300/year for parking. In 25
years, the expected lifetime of the panels, the extrapolated tax subsidy for
my UCLA parking permit will be much larger than for my solar panels and, in
fact, be comparable to the subsidy I received from the Department of Water
My wife felt very strongly that the panels should not be
visible from the street, and therefore they were probably not quite as
tilted as required to fully optimize their production over the course of a
year. Domestic tranquillity was assured at the cost of a few hundred
There was a slight leak in the roof after the panels were
installed. However, the contractor resealed the system, and there are no
longer any problems --even during torrential rains.
When we replace our 18 year old energy-gobbling refrigerator,
we will be closer to using 2000 kilowatt hours/year. However, even now, our
panels provide enough energy both for our house and electric car; the end
of gasoline and electricity bills for a lifetime. This home experiment
suggests that transition to a sustainable, modern economy is within
technical and financial reach. It is most pleasing to have an inexhaustible
supply of energy from the Sun.
The rooftop array. The peak production has been
about 2400 W from these commercial SolarWorld crystalline silicon panels.