How much solar power do I need to run a well pump?

The number of solar panels needed to run a well pump depends on the HP of that well pump. RPS systems range from only needing 2 solar panels (100W each) for a 1/2 HP pump to around 20 solar panels for a 5 HP. The RPS 200 is the 2 panel system, the pump itself is a DC pump using a permanent magnet motor. DC pumps are ultra efficient because they take the DC power directly from the solar panels and send the power down through the controller to the pump. Two panel solar pumps will run the entire day, just like a twenty panel 5 HP pump, as long as the sun is shining. Smaller systems like the RPS 200 will only pump around 3 -5 GPM.
When a project requires a high volume of water or a pump for a very deep well, you’ll need to upgrade to more solar panels and a higher HP pump. For example, an RPS Pro 5000V pumps up to 225 gallons per minute- thats 81,000 gallons of water per 6 hours!

For climates with less sun
Winter is tough for some areas of the united states if they depend on solar power to provide water 24/7 for household or livestock water. Household water systems typically use batteries for 24/7 pumping – meaning you could take a shower in the middle of the night using a battery that was charged up by the solar panels during the day. Since the solar day is shorter in winter, and the suns rays are often times obscured by the weather, RPS recommends adding a few extra panels onto the system. More panels means a larger solar panel footprint to capture scattered sunshine, which results in faster and more efficient charging of batteries.

Extended Pumping for Ranchers
We’ve seen great success from ranchers who aren’t using batteries but want to extend their pumping day by a few hours in the morning and evening, while the sun is either rising or setting. Adding a few more panels in parallel allows those ranchers to keep pumping until 6,7 or even 8 PM with very little sunshine available. Check out a story from one of our ranchers about using an RPS 800 for longer pumping days: https://www.rpssolarpumps.com/customer-stories/dougs-slow-flow-livestock-well/