Solar pump

I would like to use solar power to pump water from a pond to the top of a hill, about 100 vertical feet. It would pump into a reservoir of sorts (tbd) at the top which then could be used with a drip irrigation system to regenerate an over grazed hill. Super low flow is ok, I want a passive system that just runs all the time.  100 gallons a day would be cool, more or less would be cool too.

Advice, thoughts, recommendations?

Lots of choices.  Most likely what you want is a batteryless system that just consists of a pump, pump controller, and a panel/set of panels.

Batteryless controllers feed DC current directly to the pump, which usually runs at > 24V.  You can use large grid-tie panels, or wire several 12V panels in series.  Search the web for "solar pump controller".  Take a look at this site. https://www.solar-electric.com/residential/solar-water-pumping/pump-controllers-current-boosters.html

Pumps I've seen are in the >300W range, so two grid-tie panels wired in series might work well for you.

check out this thread for some ideas and links:

https://permies.com/t/171546/Pumping-water-downhill-dam

With even modest sun I was able to pump 400 gallons per day with a setup that could be had for 200-300 bucks. I am only pumping about 60 feet, but one of the DC well pumps I mention in that other thread would easily handle your site conditions.

Thanks team! I’ll definitely check out the advice and report back once some progress has been made.