Solar Powered Water Pump

How to Run a Well Pump on Solar

April 20, 2020

Daniel Mark Schwartz Profile Picture

One question I commonly get from people building an off grid power system, is whether they can run a deep water well pump from a solar system. So, today I decided to answer that question for everyone.

Is it possible to run a submersible well pump from solar power? Yes! With a properly sized solar system, you can run a well from solar power. You generally have two options for this, an AC pump with inverter, or a DC powered well pump designed for use in an off grid systems.

Since a well pump could easily be the biggest electrical load in your off grid system, it is worth taking the time to consider your options. Below I’ll go over whether you should choose an AC pump, DC pump, or flexible pumping system for your homestead.

Best Well Pump for Off Grid Power Use

While every offgridder has their own needs, in most cases I recommend going with DC submersible pump, such as this ECO-WORTHY 12V submersible pump, when buying a new system.

If you already have a pump in place and want to stick with it, or can’t find a DC pump that meets your needs, then be sure to get a high quality inverter that can supply sufficient power to the pump.

Choosing a Deep Well Submersible Pump for Use with Solar Power

When designing a solar system, you have two main options for submersible pumps: typical AC pumps, and purpose built DC pumps. On the market there are also a few flexible pumps that can run off either AC or DC.

AC Water Pumps

The biggest advantage of AC pumps is that they are by far the most commonly used. Since all grid connected homes run of AC power, pretty much every submersible pump in the United States runs off either 120 or 240 volts AC. This means that you may already have an AC pump, or can get one cheaply. Also, since these pumps run on a higher voltage, you may save money on wiring costs, since higher voltages can run on thinner and cheaper wire.

The biggest disadvantage to running and AC pump on solar is that you will need a high power inverter to run the pump, which will add several hundred to the final price. Inverters also reduced the overall efficiency of the solar system when compared to running directly from DC power, which means you may have to increase the number of solar panels or size of your battery bank to account for the loss.

DC Water Pumps

The biggest advantage of running a DC water pump on an off grid system is that they are higher efficiency (not needing an inverter). This means that usually, if you are buying a new pump then choosing a DC pump is the lowest cost choice, when you consider the potential for savings on invert, battery, and solar panel capacity.

The biggest disadvantage to choosing a DC pump is that you will probably have to special order a new one, as DC well pumps are not very common. They also tend to run on lower voltages, which means extra costs if you have a long run of wire between your batteries and your pump. DC pumps also tend to only be offered in lower to medium capacity models, so if you have high water usage, you may have to stick with an AC pump.

Flexible Pumps

At least one maker provides pump systems that run from either AC or DC power. This is definitely an option to consider if you plan on running a pump grid connected most of the time. Or, if you are connecting the pump to a wind generator or micro hydro generator that produces AC power, but would also like to run the pump from batteries on occasion.

How Much Power Does a Submersible Pump Use?

Typical home size well pumps use about 750W – 1500W while in operation. Check the power rating on the body of your pump or in the manual to see exactly how much yours will draw.

The amount of energy that a pump draws depends on how long you run it, which in turn depends on how much water you use. Running an 1000W submersible pump for 1 hour a day would require 1kW of energy, delivered. For more information on how to size your solar system based on the required load, check out my article below:

How long you run your pump in a day is, of course, closely related to how much water you end up using. Most well pumps can move between 10 – 30 gallons per minute.

Should I Buy A Solar Pump Kit?

One option that many offgridders consider is buying an all included solar pump kit. These kits are usually sold to ranchers and farmers who need an easy, self contained method to pump up water for their herd. Most solar pump kits include everything you need to make it work, including solar panels.

If you definitely want your pump to be completely self contained, either because it is a long way from the rest of your solar system, or you just want a backup in case the main system fails, then solar pump kits are a good option.

However, if you are already installing a solar system to run other parts of your home, then buying an all inclusive solar pump kit isn’t worth the cost. Generally, up sizing a single system in the design, going from a 3kW to 4kW system for instance, is cheaper than buying a kit.

Can I Use a Hand Pump Instead?

If you are looking to save money over a pump system for your well, you might consider installing a hand pump instead. Also, you might consider a hand pump as an emergency backup for your electric pump.

However, for the majority of wells, which are deep wells, you cannot use a pump on the surface. Thus you can’t use a hand pump.

Hand pumps work by sucking, which means they can only pump water up 25’ from the static head of the water below. This limitation is due to barometric air pressure, and the only way to get around it is to use a submersible pump that operates in the bottom of the well rather than the top.

Since most wells in the United States means for human consumption are deep water wells, almost all of them will be deeper than 25’, making and submersible electric pump the only option.

Can a Well Run from Solar Power?

Yes. Submersible well pumps run great on solar. You have the option of converting your existing AC pump to solar with an inverter, or buying a DC compatible pump for your well. There are also stand alone solar pump kits readily available, that come with everything you need including solar panels to run the pump.

Can I Convert My Well To Solar?

Yes. Coveting an existing well pump to solar is straight forward when using an inverter, which converts the DC power from solar cells and/or batteries to the AC that your pump runs on. You also have the option of replacing your well pump with a DC pump, removing the need for an inverter.

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