How much does a commercial solar panel cost?

Current prices for the PV modules themselves are about $4000 per KW (peak), the total installation will of course cost more. A domestic system, if it is going to be able to replace your normal supply, would have to be around 5 KW at least. That should cover lighting, TV, Computer, and a few other appliances, but you would need your normal supply to provide enough power to cope with larger appliances such as washer, dishwasher, clothes drier, etc. You can see that at least $20,000 could easily be spent, and there would be extras like the inverter to produce AC power.

Answer:

One can lower its Solar panels cost by visiting some surplus market. Many companies sell there liquidation in surplus market in very low cost. You can also find solar panels form such market in very low prices.