I promised to tell you more about our use of solar energy. After having re-build our house last year we now make us of solar energy in 3 ways:

* Solar cells for 220 Volt on-grid electricity
* Solar panels for heating water combined with floor heating
* Passive heating through a huge thermo glass area facing south.

First we got the photo-voltaic cells. Our roof is perfect for this, facing south in an angel of 45. The disadvantage of this system is the price, but in 2003 we got selected for a project called “Sun 2000″ in which different organizations and state subsidies paid 60 pct. of the total price. Our price was about 6.000 euro, but what really made this project interesting from a financial perspective was the agreement with the local power company: The system is build to produce 220 V and it is connected to the grid. Normally if you produce electricity for the grid you will only get paid the basic price pr. kW. But when you buy you will have to pay the basic price plus taxes. Since the taxes make about 3/4 of the power bill this would not be interesting for at all. Instead we now can sell power at the same price as we buy as longs as we produce less than we use pr. year. This is great because the system produces about 1/3 of our total power consumption. The system is build of 6 BP panels at 170 WP each which will produces about 800 – 1000 kWh/year. To generate 220 V for the grid and our own use we have 1 Fronius micro inverter. This is no in longer in production, but has been replaced by a new series of Fronius inverters, the IG series.

The cells have been very stable during the years and there has been no maintain at all or reduction in effect. The investment will break even in about 14 years from now.

Next to the solar cells we have the water heating panels. I bought them as a solar diy-kit for about 2.000 euro and this has proven to be the most rewarding alternative energy investment we have done. The kit had 2 panels at 2,4 m² in total 4,8 m² a 220 liter tank with two spirals, all pipes, fittings, pump, electrical controls etc. I used a couple of days to set it up and it has run with no problems since.

As you can see from the diagram the water tank is connected to a secondary source of heat, our wood stove. What is smart here is that the wood stove heats via the top spiral in the tank, and makes sure we always have at least hot water enough for a couple of showers. The solar panels heats form the bottom of the tank. The idea is that when it is summer and the sun is burning the system can easily heat up the 220 liters to 70 degrees, sometimes even 95 degrees! In the winter the panels seldom gets warm enough to give us hot showers, but it can heat the cold water that comes in from below usually to about 30-40 degrees, leaving the rest of the job to the wood stove.