I am posting this for someone else who lives in Italy. Here is his question:

My two wells both have submersible AC pumps (here in Italy 220 VAC) and I want to convert one to a solar powered submersible pump, so I can come off the local water supply network without incurring additional power costs, not to mention the satisfaction of having my own independent water supply, green and carbon friendliness etc, etc.

Researching on internet and getting some quotations, 24 VDC submersible pumps are very expensive here in Europe, almost 4 times as much as an AC pump. It occurred to me to use an inverter with the solar system and use an AC pump, but I wonder about the reliability and efficiency of this approach. I haven't done the calculations for how big an array with an inverter, I should imagine a bit bigger then the DC pump, due to energy loss etc.

My gut tells me that the DC version will be a better solution in the long term, if nothing else one less component to break down, and the DC pumps designed for solar come from a companies dedicated to the engineering of such (one Danish, one German) rather then a mass producer of pumps. Reliabilty is what I am looking for. However if an inverter system (and I have no experience of these things) works as well and is a lot cheaper, my local pump & well shop is very good at servicing plain old AC pumps. With the DC pump I would need to send it off to the service agent somewhere in Italy.

What should I get for my solar pump?