I think it's worse than that, for rooftop solar you have an enormous amount of sales and marketing expense baked in, plus you have homeowners which don't have e

I think it's worse than that, for rooftop solar you have an enormous amount of sales and marketing expense baked in, plus you have homeowners which don't have enough experience to know what a good price/good install looks like. Much less of that with bigger systems. The other major problem is the grid is not setup at all for consumers to also be generators. At least in the UK it is rare/not possible for the DNO to send power back from a neighbourhood to the grid (at least not without a total remodel of the local grid infrastructure). So we are now hitting problems where solar is not allowed to be connected to the DNO if you have streets with a lot of solar on, because at some point the generation from the houses on the areas local transmission outstrips the demand in summer, and in that case you have too much power and nowhere for it to go (the excess cannot be sent back to the high voltage grid). The DNO cannot turn off individual solar generators easily (and even if they could, do they trust a load of chinese inverters to work reliably remotely?) I think the key problem with solar/renewables is not undersupply in winter in northern climates (though that is a big one for true net zero) it is oversupply in the summer. It's already causing massive issues in Europe with long spells of negative pricing. Interconnectors don't really help with this because when it is sunny (and potentially windy) in one place in Europe it tends to be similar elsewhere, so everyone has too much power. This is before the UK adds another huge amount of solar and wind in pipeline by 2030. Note this comment only applies to northern climates. It's far less of an issue further south because AC load tends to follow solar production much more, but that is far less common in the UK.