During normal operation, the solar air collector get started as soon as the sun shines. - The sun's rays will generate electricity in the solar cell, which will then get the fan to run. The fan will pull fresh air through the backboard and absorbe felt - inside the solar panel. The air will be warmed up and blown into the house.
On hot summer days, you will not need extra heating. Here you can turn off the system and thanks to SolarVenti patented backboard, the collector is able to cool itself, so there is no overheating. SolarVenti is the only air collector on the market that can cope with passive cooling even under extremely sunny climates. Other models have an extra fan to it.
When you switch off the fan on a sunny day, the black absorber felt gets over 80 degrees Celcius and will then start a self cleaning proces drying out all germs etc. that might be in the felt.
The SV20 is now manufactured with a solar cell placed in the backboard for several reasons.
1) you may replace the solar cell in a few minutes without special tools
2) the temperature of the solar cell will lower some 20 - 25 degrees under extreme warm conditions
3) the lower temperature of the solar cell gives a higher electric output for the fan
This methode is never seen before - and is applied for patent. Later (autumn 2013) the SV14 will be produced in the same way.
See also SolarVenti Demo Video