Much of the world gets literally twice the sunlight as most of Germany and that's the annual average. When talking about the winter time, the difference can be more like a factor of 5 or more when taking into account heat needs.
I fail to see why people use northern Europe as the baseline for their solar arguments when it's clearly a cornercase, given a global perspective.
What's the purpose of solar farm in Sahara? Lack of a need for electricity (except AC, but not many there can afford it) and transferring power over long distances is not effective.
For home heating there are other energy sources, not as clean (well maybe except wind, which blows during winter also): coal, gas, oil and nuclear.
