When does a PV panel pay for itself?
Now I know that many would say we should do it out of principle, but I’m only going to do it if it actually pays off. I’m all about taking care of the earth God gave us, but I have to be practical until I’ve got a few more bucks to play with.
SO… What is the most cost effective solar energy source for a single family home, and how long before I can expect it to pay for itself.
I also realize, of course, that there are a lot of variables in here, the biggest of which is the efficiency of the home itself. Efficiency upgrades are the first steps we are looking to take, but I am interested in PV technology as well.
Thanks!
In general solar thermal applications will pay for themselves faster than solar photovoltaic panels. This is because although photovoltaic panels in the lab have achieved efficiencies of around 40%, the ones you buy only achieve around 14%. Solar thermal panels can be 60 to 80% efficient. The technology is hundreds if not thousands of years old and much cheaper. The solar thermal vacuum tube collectors will work on cloudy and cold days.
But governmental and utility incentives help to bring down the payback period of photovoltaic as well. In general the more use you make of a photovoltaic system the quicker the pay back period. So it may not be cost effective to put in a geothermal heat pump and power it with photovoltaic. Cheaper electric resistance heat seems to work better.
With solar thermal cost will rise as you go from 80% to 100% usage. Depending upon the alternatives an 80% capacity system may pay back better than a 100% system.
Solar thermal:
Hot water systems can have pay back periods of 3 years or less.
solar heating applications may have a pay back period of 7 years or less.
Solar air conditioning is the latest entry into the solar thermal field and I have not yet seen payback numbers on this.
Photovoltaic:
Payback periods of 10 to 20 years are not uncommon.
Using an electric car helps to lower the cost as does time of use metering with the grid as a "storage device." Below is an interesting article about the payback of a photovoltaic system that helps give the tesla roadster a 72 mile range using solar electricity alone.
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In general solar thermal applications will pay for themselves faster than solar photovoltaic panels. This is because although photovoltaic panels in the lab have achieved efficiencies of around 40%, the ones you buy only achieve around 14%. Solar thermal panels can be 60 to 80% efficient. The technology is hundreds if not thousands of years old and much cheaper. The solar thermal vacuum tube collectors will work on cloudy and cold days.
But governmental and utility incentives help to bring down the payback period of photovoltaic as well. In general the more use you make of a photovoltaic system the quicker the pay back period. So it may not be cost effective to put in a geothermal heat pump and power it with photovoltaic. Cheaper electric resistance heat seems to work better.
With solar thermal cost will rise as you go from 80% to 100% usage. Depending upon the alternatives an 80% capacity system may pay back better than a 100% system.
Solar thermal:
Hot water systems can have pay back periods of 3 years or less.
solar heating applications may have a pay back period of 7 years or less.
Solar air conditioning is the latest entry into the solar thermal field and I have not yet seen payback numbers on this.
Photovoltaic:
Payback periods of 10 to 20 years are not uncommon.
Using an electric car helps to lower the cost as does time of use metering with the grid as a "storage device." Below is an interesting article about the payback of a photovoltaic system that helps give the tesla roadster a 72 mile range using solar electricity alone.
References :
http://evworld.com/article.cfm?storyid=1733
here is a simple formula
cost of system per watt less rebate (say 33%) divided by peak watts of system times your local rate in $/kw-hr all divided by 2.
so a $10,000, 1000 watt system in an area where electricty cost $.15/kw-hr,and the federal plus local rebates are 33% the equation is
((10000 * (1-.3333)) / (1000 * .15) ) / 2 == (6666/150)/2 = 44.44/2 or 22 years later your system will be paid off. Of course, you have a 50% chance of having to replace them 20 years from now.
References :
Solar Thermal is definitely the most inexpensive and fastest pay off in the Renewable Energy field. Watch the free webinars which are provided via the link below. They offer great, useful information and can help you decide where you want to start.
Good Luck!
References :
http://www.altestore.com/store/Books-Classes-Educational-Videos/Educational-Videos/c1138/