Your Questions About Solar Panels Cost

Henry Dover answers:

There are several types, some for electric power and some for hot water.

ROI is most dependent on your location and the positioning of the panels (the amount of ambient sunlight per year).

Henry Dover answers:

Hi Kate,

As I am from the states it took me a bit to figure out just what is a “Bach.” I have had some embarrassing difficulty with other words when I was in New Zealand so I am not surprised. We might call it a “trailer home” or a “mobil home” but I like your word better.1

At the risk of giving you more information than you wanted: “Solar panels” can come in many different dimensions and sizes. But first you should know that there are solar photovoltaic panels that are used to produce electricity and while experimentally they have achieved efficiencies around 40% what you can buy will be around 14% efficient. Because of the reduced efficiency you have to use more of them. This site gives you some information about sizes and prices. 2

I have a small one (about 25cm by 35cm) that was shipped with a car to keep it’s battery charged from the factory to the dealership. It produces a “trickle charge” of just over 12 volts DC and is meant to plug into the cigarette lighter. If your Bach were only going to use 12 volt DC power with batteries for night time use then the connections would be simpler but if you needed the standard New Zealand voltage of 230 volts at 50 cycles AC you would have to use an inverter to change the power from 12volt DC.

But there is also another kind of “solar panel” and that is the Solar thermal panel. This is a much older technology. Because it is used to gather heat from the sun it is much more efficient. Around 60 to 80% efficiency is possible. It is a good idea to take a lot of the load off any photovoltaic requirements by first installing solar thermal panels. This is a way to keep the cost at a minimum. Solar thermal applications can be used for heating hot water, space heating, and even air conditioning and producing electricity. The panels available can be used on colder and cloudy days as well. (vacuum tube collectors)

Good luck with your project.