Electric power from solar panels can replace gasoline used in automobiles
|Total power available from the full sun in a clear sky
at a 90 degree angle is about 1 kilo-Watt ("kW") on each square meter (a little larger than a square
yard). Commercial solar electric Photo-Voltaic ("PV") panels produce electricity at an efficiency of
at most 20%, while the most expensive military PV is 30% efficient. So the most each square meter of PV can yield
is .2 kW, or 200 Watts of electric energy.
Over the hours of the day, the sun's angle and cloud cover changes; as a rule of thumb, there are 5 hours of full sun per day. Thus the most each square meter of PV would yield is about 1 kilo-Watt-hour ("kWh") of electric power (enough electric energy to keep one 100 Watt bulb burning for 10 hours). Taking into account system losses and space between the panels, each square meter of PV will yield at least half the maximum, or about .5 kWh per square meter per day.
The average US car gets 20 miles per gallon, and USA gasoline consumption is about 400 million gallons per day. Our total number of miles driven using gasoline is about 8 billion ("B") miles per day.
If those miles were driven entirely in plug-in electric cars like the Toyota RAV4 EV, electricity could effectively replace gasoline. The RAV4EV gets over 3 miles for each kWh of electric power it consumes.
To entirely replace gasoline with plug-in Electric cars using solar PV would take about 2.3B kWh per day. To provide all this energy via solar power would require about 4.6 B square meters of PV panels (dividing 2.3 B kWh by .5 kWh per square meter).
This is a lot of space, approximately 1500 square miles, or 30 miles by 50 miles full of solar panels. But like automobiles, the PV panels would be dispersed among the 100 million households and 200 million cars in the USA. If all 200 million cars were crammed into one giant parking lot, it would take a lot of space, too, about 4000 million square meters or 1200 square miles of solidly packed cars, packed even tighter than solar panels. And then, there are the refineries and gas stations, too, which would take many more hundreds of square miles.
If the solar panels were dispersed onto the rooftops of, say, 100 million buildings, it would only take 46 square meters per building, on average, about 500 square feet of roof space. That's less than a quarter of the roof of the average home. Siting PV panels on roofs also provides shade, reducing cooling costs and extending roof life.
It would take a national commitment to a program of building Electric cars and producing solar panels to entirely replace gasoline. While solar panels require a lot of space, so does the gasoline infrastructure; and moving to solar power will reduce or eliminate overseas oil imports required to produce our gasoline.
Of course, solar power produces energy in the daytime period of peak usage, while it would be more efficient to recharge the plug-in cars overnight. Connecting the solar panels to the electric grid would lower its vulnerability to failure of high-voltage switching gear and would help even out the daily electric usage curve.
By moving toward plug-in electric cars and roof-top solar energy, we can cut gasoline consumption, cut pollution, cut oil use, phase out refineries and their detritus, secure our energy supplies, strengthen the economy, increase our national security, and, with optional battery backup for each home, improve disaster preparedness and emergency response.