Solar energy, heat pumps, and other renewable energy sources that can be misleading

For many years, I've assumed I was going to get solar panels when I had a house, because I assumed they not only save the environment but save money in the long run. However, after doing some calculations, it turns out this may not be the case.

First of all, it must be understood that things like solar panels and heat pumps (which are devices that produce more heat per joule of electricity used than normal electric baseboards) are not without environmental harm. It takes energy to build them, and that energy probably comes from fossil fuels. An estimate of how much energy they use is their price. Therefore, in general, an energy efficient technology is only worth buying for environmental reasons if it pays for itself.

Let me show you my calculations for various technologies. First, my situation is that I live by myself in a mini-home. The "energy used" section of my power bill has been about $25 in the summer months, and I expect it to be about $75-$100 per month in the winter (I try to keep the temperature down in the winter). I have regular electric heat and an electric, tank water heater, which are about the most wasteful technologies, but they came with the house so I already have them. Electricity for me costs $0.10 per kWH. I live in a cold, humid climate.

• Solar panels: I just did a quick search, and found a 130W solar panel that costs about $716.10 (energymatters.com). This would save about $40 per year: 0.05KWh/h = 1.2kWH/day = 36KWh/month = $3.60 per month = $43 / year. This isn't counting all the extra apparatus you have to install either, such as an inverter, a battery, or installation. At $43 per year, it would take almost 20 years to pay for itself, by which time it may well be broken, or they may have a much more efficient technology.


• Solar water heater: Two contractors each gave wild guesses that one of these would cost about $3000-$4000 for me. They plug into my main water heater and preheat the water, so the main water heater doesn't need to use as much electricity keep it hot. Since I'm buying only $25 worth of electricity in the summer, this couldn't possibly save me more than $20 per month (and would probably save much less). At $20 per month, it would take 20 years to pay for itself, by which time it would probably be broken.


• Heat pump: One contractor made a wild guess that one of these would cost me about $3600. I'd estimate that it would cut my heat costs in half, and since I would spend about $75 per month on heat for about 4 months, this would save about $150 per year. So again, it might take over 20 years to pay for itself, by which time it would probably be broken. (However, these can also be used for air conditioning, so people who insist on getting an air conditioner could get a heat pump instead. I don't have an air conditioner or see the need for one in my cold climate.)

It appears that most of the time, it's best to continue using technologies that are already built, and only replace them with efficient technologies when they break.

In summary, it's probably worth looking into such technologies for yourself, but don't blindly assume you're doing a good thing by buying them. The most important thing you can do for the environment is to shun luxury and use your own human energy to accomplish things instead of using energy-intensive devices. Once you do that, it's likely you'll find that "renewable" technologies aren't worth it after all. (In fact, with respect to heat, it would be ideal if there were few enough humans that we could just live places where we can tolerate the natural temperature year-round.)

On the other hand, these technologies would probably be great for large buildings used by many people, or for large houses which large families live in, and may pay for themselves pretty quickly in those situations. Likewise, someone building a new house may find it more worthwhile to give it renewable energy technologies in place of traditional ones, since traditional ones also cost a lot.

There's also the possibility of building things yourself from old parts, in particular building your own solar water heater. This may save enough resources to make it worthwhile, though I think you may have to live in a warmer climate to be able to use the particular type of solar water heater that's easy to build.