Yes, 100kBTU/hour, which I assume is what you mean, is 29kW, which would be 133 amps at 220 volts, or 610 amps at 48 volts. But solar only supplies power intermittently; you'd need to draw much more power than that when the sun was shining to blast your mansion with 29 scorching kilowatts around the clock. Maybe 100kW, about 2000 amps at 48 volts. For that you'd need ten parallel #0 wires (8.3-mm-diameter copper bars) or the equivalent amount of copper divided among more wires. If it's running four stories from the parapets of your sprawling castle down to the physical plant in the basement, say 16 meters because of all the vaulted ceilings, we're talking about 160 meters of #0 wire, 76 kg of copper.

That's US$833 of copper, and probably US$2000 worth of wire, but it's also US$12000 of solar modules at current international wholesale prices. So the wiring is kind of the least of your worries!

But there's no need to get 2000-amp service from the electrical utility.