But it would reduce the demand on the grid from that building? So that’s a plus?
Different scenario. In that case you have something resembling an actual power plant - something with megawatts of output. And the economics of it mean that you want that array operating at its maximum power point all the time; if it’s forced to operate off the MPP, you’re losing money. Same is true of almost any other source - they all have a certain narrow range of power output at which their operation is optimized (in terms of money, fuel efficiency, lifetime, etc). So somewhere along the line(s) the grid will have to be upgraded to absorb that extra capacity from another point source. You’d have to do the same thing if you added a gas-fired plant.
The complication with solar is that you have to size the conductors for the rating-plate power output of the array - but unlike a nuclear plant, it rarely operates at that point. That means you’re spending quite a lot of money on cables to transport (say) 1MW when, for most of the time, you’re getting no more than 0.5MW from a solar array with a nominal 1MW output, because that’s just the way sunshine works. It spends about half its time generating next-to-nothing, of course, cos it’s dark. That’s why grid operators are less than keen to do it, or charge the operators of big solar arrays lots of money. It’s just a very poor use of materials.
The details are a lot more complicated than that - I don’t pretend to know all the black arts that go into the management of the grid. But that’s the outline.
Sort of. It would certainly reduce the community power bill (as long as they’d done the original installation in a sensible and cost-effective manner). But it probably wouldn’t affect the sizing of the grid connection, because, as above, you have to allow for worst-case.
Distributed PV is almost always the best way of doing it - big solar farms are often a suboptimal solution, for all sorts of reasons. But it has to be carefully assessed on a case-by-case basis. There should be soft incentives, not “mandates” or subsidies.
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In that case you size the conductors to carry 0.5mw, and use higher temperature insulators or active cooling for the rare chance that it actually pushes to 1mw. Or you have batteries to soak up the extra output or simply limit output.
Sure you can introduce tradeoffs. But there are all sorts of subtleties here. The nature of I2R heating is that 2x the current means 4x the temperature rise (crudely speaking), so if you’ve sized your conductors for (say) a temperature rise of 20’C when carrying 0.5MW then they’ll be running at around 100’C at 1MW - even if only for a few minutes or hours. Apart from the rise in resistance (which will cause them to get even hotter) they will start to sag. Grid operators have all kinds of complex design rules which may not be strictly necessary and could in theory be tweaked for the precise operating conditions, but if you’re operating a business with extremely demanding constraints on safety and reliability, you’re not going to start fiddling with stuff just to save a few $, especially if you can just pass that cost on to the customer.
The good use is less so high rise perhaps and more the vast foot print space hogs and are only a floor or 2. loads of factories, warehouses, distribution etc have massive flat roof tops collected heat rather than collecting juice and shading the building under it, reducing juice use 
It’s not a solve taiwans issue thing, merely an easily obtained input for a few %.
our work has a completely useless flat space on top of about 300 square meters heating up the building. covered in panels, it’s a solid 5 degrees cooler in summer.
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Uh-oh.
The fish in the water under the solar panels are all dead. And it smells.
The light bounces of solar panels and hurts people’s eyes during the summer.
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Fecking idiots. I like solar panels, but it seems like they don’t have a clue how to deploy these things properly here.
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Maybe ineptitude with a dash of malicious compliance?
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