Of course the example is wrong because for most of the places it is resolved by simply having a larger PV array so that even winter generation is sufficient. Th

Of course the example is wrong because for most of the places it is resolved by simply having a larger PV array so that even winter generation is sufficient. That will probably not work for 60N, but easily for 40N: an array about the size calculated for 60N, used at 40N, will not require any seasonal storage. And of course, nobody uses storage like that. Off-grid system must combine solar and wind, wind typically gets stronger in winter, plus about 24 hour worth of energy consumption in storage (a couple Tesla systems), and finally a diesel generator for a few percent of the total generation for the unlucky days when sun doesn't shine and the wind doesn't blow.