You're all falling into the trap of average daily power usage. The heliostat needs to provide the peak power draw, not the average power draw of a house.
I'm a South African and while my 3 person house averages 700W power consumption over a 24 hour period, my peak is close to 10kW if I've got the stove, water heater and kettle going at the same time. That happens regularly in the early evening or mornings. And yes, we have electric stoves and water heaters because we don't have a gas infrastructure like Europe or North America.
Our electricity rates per kWh seem to be comparable to the US rates, 10 US cents to 14 US cents per kWh for my city's inclined tariffs. But solar installation costs are high, a 10kW installation with batteries to hold overnight can be around $25000 and the batteries will have to be replaced after 6-9 years at around $8000. My house uses roughly 1000 kWh a month for a bill of $110. So the capital cost would pay off over 19 years, but after a maximum of 9 years, I'd add another 6 years to that. And for the average working and middle class South African, $25000 as a capital expense is a harsh layout.