We put a system back in May, our pump wis 1600 Watt each of our panels is 400 watts, each one was 3500 ,baht the guy who did all the buying and fitting said we needed 6 panels ,which we got first time on start-up we got a fault code come up, saying too much voltage /power ,so we disconnected two panels now no problem.
As for pump,ours is a 3 inch pump ,which I put on a reducer making it now two inch ,works well ,the reason was, we are pumping 200 meters ,thinking that distance and water volume the pump would not pump all that water ,I think I am wrong, as said another AN member who knows more than me ,saying friction on the smaller boar pipe slows the water flow ,but buying new 3 inch pipe plus all the joins/fittings will cost 20 000 baht plus, as opposed to the 8 500 baht for the 2 inch pipe.
But the pump with the 2-inch pipe can work with a 2inch sprinkler with a about 25-meter radius which is ok, but soon as a cloud appears the radius drops to 15 meters.
Normalee starts up at about 9-9.30 am.it can keep going until 4-30 pm,as has been said about 7 hours day.