The requirement for a flat inclining towards east and west roof influences the decision for the photovoltaic.At unfavorable alignment is amorphous silicon from Unisolar favorite.
Electric power in winter at bad weather conditions is the new target. Not the maximal electric power shield over all the year is the highest target, but an uniform power supply.
Maximal power yield increases summer winter difference
The design for a maximal yield increases the difference between summer and winter. Best example for this is the GEMINI house designed by me. On the day of summer solstice 16 hours exactly aligned towards the sun. But when it is sunny on the day of the winter solstice, tracking brings only very few additional yield.
Power supply in the future
Wind and sun are delivering on a good day more than the demand. On a sunny summer day, water storage power plants will pump up water with solar power. Biogas and wood power plants deliver quickly, when sun and wind are not enough. Electric power tarrifs will be dynamic by supply and demand. Not only for the power producers, but also for the consumers.
Full roof area for maximal yield at cloudy weather
No photovoltaic on the roof! No! All the roof has to be photovoltaic. The photovoltaic roof should be big. As much excess towards the house as possbile. 12m x 12m is the target. 144 squaremeter Uni-Solöar to convert also scanty light into electric power.