You're probably mistaken [edit: no, I was wrong] about whether they're good investments for home usage and whether government subsidies would be needed, but maybe you live in a country where import tariffs make the panels cost a lot more than they cost on the open market.

By "large" do you mean something more like 0.01 m², 0.1 m², 1 m², 10 m², or 100 m²? Any of those is a "large panel" in some frame of reference.

They're not a good investment due to high cost of the panels compared to the price of electricity. Which to be fair is heavily subsided be the state. I'm looking forward to install ones myself, but I'm in the 90th percentile of people in my country that can afford to write big check upfront for power for home usage. Again most of the usage now is limited to agriculture since it makes sense there financially.

By large I mean around 2m² each. Not sure the best size to capture the most out of the sun. But we're at the edge of the Sahara desert, so the climate is a little bit helping there.

Interesting! Yeah, if electricity is heavily subsidized, you're probably right that solar panels are unprofitable. How much does electricity cost? Why don't the agricultural water pumping folks use the subsidized electricity instead of installing solar panels?

0.021 usd per kwh. Farmer are sparsely located, so linking them to the main grid is costly as they need to pay for it by themselves.

Hmm, if we use €0.19/Wp as the price, US$1.08/€ as the exchange rate, and 30% as the capacity factor (I'm assuming it's a bit sunnier than Arizona, which has a 25% average capacity factor for utility-scale solar), the payback time is only 3.7 years. That seems like a pretty profitable investment even despite the subsidized electrical rate.

To be concrete, a 200-watt solar panel should cost about US$41, and produce on average 60 watts: 0.06 kWh/h, which is US$0.00126 per hour, US$0.03 per day, US$0.92 per month, US$11 per year. So in a bit less than four years, it pays for itself, unless the subsidized price of power drops by then or someone steals the panel. If we include a motor scooter battery and cigarette-lighter inverter so you can plug regular appliances into it, even at night, the payback time jumps up to maybe ten years.

Maybe you're mostly saying that US$41 or US$100 is a lot of money to invest up front, or maybe the problem is (as it is here in Argentina) that panel prices are wildly inflated by corruption.

Last time I was installing panels, they were cheap even the mono ones, but there were other costs like mppt charger, batteries, inverter and DC wires (copper is expensive) when I summed it all, I got to the breakeven point in 10 years.

Now I am thinking about grid connected setup but still AC module isn't cheap if they were only $50-$100, like the enphase AC units embedded into solar panel itself, it would be worth it. But it nearly doubles the price so I've not installed any panel yet.