Solar panels have declined in cost dramatically in recent years, and are still in free-fall. Federal tax credits as well as tax credits offered by some states, as well as incentives from local power companies, municipalities, etc. make the cost of a new solar system worth considering. As one who has consumed his share of the world’s resources and would like to atone for his past indiscretions, I looked into placing some solar panels on my property. Here is what I found.
In round numbers, the cost of solar kits is about $3-4 per watt, uninstalled. Add $1-2 for each watt for a total of about $4-6 total. The federal government grants a 30% tax credit, and many states grant a further %30 credit at the state level. In addition, some utilities provide a rebate of varying amounts depending on the total installed. The net total cost to the end-user is about $2-4 per watt, including installation. Search the web to find the specifics for your area. The rules and regulations are in a state of flux, so be cautious of the results and verify before making a financial commitment.
Once installed, and depending greatly on the area in which you live, the panels will generate up to about 6 watts for each watt installed. Thus, a one kilowatt installation costing about $2,000-$4,000 will generate up to 6 kWh day over the course of a year, in the sunny Southwest USA. This amounts to a return of about $18.00 month (at $0.10 per kWh) on a $2,000-$4,000 investment, depending on electrical rate, final purchase price, etc.
I also examined what I could save in energy consumption. As Ben Franklin would have said, a watt saved is a watt not generated. My biggest electrical energy consumer is a hot tub, which I use about twice a week, at a temperature of 104. When not in use I turn the heat down to 80. I can determine the energy the tub consumes by measuring the heat lost over a period of time, and therefore the watts needed to heat it back to its original temperature.
For example, my tub left unheated declines in temperature at the rate of 4 degrees per 24 hours, in my case from 104 to 100. If I want to heat the water back to 104, I need to raise the water back to 104. How much energy is required?
The volume of my tub is 350 gallons, and a gallon of water weighs about 8 pounds. So I have 2,400 pounds of water to raise by 4 degrees. We know it takes 1 BTU to raise a pound of water 1 degree Farenheit, therefore it requires 9,600 BTU to raise 2,400 pounds by 4 degrees. Conversion tables tell us 9,600 BTU is about three kilowatt-hours, which is the amount of energy my hot tub requires each day.
(These figures are very approximate, and do not account for the fact that the tub will cool more slowly as its temperature falls. Also, filtering functions consume perhaps 1-2 kWh per day, which may or may not be lost. I recover the lost heat from my motor by circulating water over the motor. Outside air temperature, wind, etc. also affect the calculations.)
Simply emptying and shutting off my hot tub is the energy equivalent of installing 500 watts of solar – two large panels for a total cost of $1,000-$2,000. With that kind of number, and with the cost of solar equipment still falling, I may postpone solar installations and consider the saving route first.