Scott Adams’ WSJ article continues to keep me thinking… in it he talks about the solar photovoltaic array he installed on his roof, and his disappointment with the results, or rather the lack thereof. According to Wikipedia, Scott lives in Pleasanton, California. If you’ve ever been to Pleasanton you’ll know that it is a fairly sunny place with a pleasant climate (perhaps why it’s called Pleasanton). A photovoltaic array probably seemed like a good idea. An even better, and less expensive, idea might have been to install a solar hot water system on the roof.
Solar hot water can be a great entree into renewable energy
Pleasanton has an average temperature of about 63 degrees Fahrenheit, which means the water that comes out of the taps is around that temperature. This is because water pipes are buried a few feet below the surface of the ground, where daily fluctuations are negligible and seasonal effects are minimal due to the insulation afforded by the soil. If you want to know the average temperature where you live, stick a thermometer in a glass of tap water (taken after the faucet has been flowing for about a minute), it should be fairly close in the lower latitudes of the continental US. If you live up north you will probably notice some seasonal effects (i.e. your tap water is a little cooler in winter and a little warmer in summer).
The upshot of this is that in Pleasanton homeowners typically use fossil fuels to heat water from ~63 degrees to the temperature of choice for clothes washing, dishwashing and showering, somewhere around 100 degrees. Solar hot water lets the sun to do some of the hard work – heating the water from 63 degrees to say, 90 degrees – and relies on fossil fuels to kick in for the final push to ~100 degrees. In this example the sun has done almost three quarters of the work, which would reduce your expenditure on water heating by almost three quarters.
Solar hot water can reduce water heating expenditure by nearly 100% in favorable regions in the summer months. In Pleasanton we would expect annual saving to be on the order of ~70 – 75% of water heating costs. Given that 14 – 25 % of energy consumed in the typical home is used to heat water, this could result in significant savings.
Of course the suitability of your house for a solar hot water system depends on many factors and only a qualified professional, such as those at GreenHomes America, can tutor you on the best options for your building. Having said that, here is a link to a quick video tutorial on solar hot water from our V.P. Mike Rogers.