Using Batteries with your Solar Pump

“Can I add Batteries to my RPS Solar Pump System?”

Yes! Here are some things to consider, and some common diagrams.

NOTE: RPS systems run most efficiently using solar power alone. While it does make sense for some customers to add a battery bank
(especially with low GPM wells and for household water pressure), whenever possible, our engineers do recommend pumping more water into
a storage tank for overnight use rather than adding the expense and complication of batteries.

The RPS Controller When set to BAT mode, the solar panels will charge the batteries, and the pump will run off battery power rather than solar power directly. (Controller’s Power light will blink) There is a PWM solar charge controller inside your pump controller that facilitates charging, prevents overcharging, and prevents discharging batteries to a damaging level. It should be mentioned that during charging, some power and voltage is lost, leading to a 15% to 25% decrease in pumping efficiency. These decreases are greater for deeper wells and higher heads.

What Type of Batteries should I use?

Batteries must be deep-cycle batteries, not standard car batteries. Deep-cycle batteries are designed to accommodate
much lower continual discharges than regular car batteries and are usually sold as “marine” or “RV” batteries. Lead Acid
Batteries are the cheapest deep-cycle batteries and are easiest to find. Most customers feel Lithium-Ion batteries are still
too expensive. AGM batteries are an increasingly popular option.

How many batteries do I need?

If you are adding batteries in order to pump more water than is possible in a solar day, you will need to increase the
number of solar panels in your system. Add solar panels in parallel to maintain the same voltage to the controller. More
batteries can also be added for greater total storage capacity, as long as they are added in parallel at the same voltage.
Batteries should be at the same voltage as the Solar Panel Array. Use 12v batteries in sets or 2 in series for RPS 200 and
400 (to make 24v) and sets of 4 for the RPS 800 (to make 48v). More sets can be added in parallel as needed, but we
recommend starting small and adding as needed. (If using 6v batteries, you’ll need double the number series!)

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