To water 10 acres of orchard in northern California, where our water levels are “good” (wells are 100-150 ft deep), we need about a 25 hp (20 kW) well pump. That’s ~2 kW per acre.
A typical irrigation cycle is on the order of 10-20 hours. So budget about 20-40 kWh/acre for a cycle, and repeat every 10 days or so (crops need to dry out between waterings else disease spreads.)
In theory, a kW of solar panels charging a 20 kWh battery for 10 days should work to water 1 acre for an entire summer season, at a capital cost of a wildly uneconomic cost of perhaps $20,000 per acre.
These are my wild guesstimates informed by some orchard experience, but please correct me if my numbers seem badly amiss.
ps: With PG&E power, we currently pay about $400/acre, per year.