How To Connect A Solar Panel To A Water Pump

Water pumps are an essential part of life. From hand crank pumps to those that power the water supply for millions of people, water pumps are the tool we use to move water in two ways:

  1. To move water in vast quantities quickly
  2. .To move water against the force of gravity.

If you need a water pump for either of these two reasons, you might be wondering how to connect a solar panel to a water pump? Solar power is a logical power source for a few additional reasons:

  • The well is rural, and there is not a grid-tied power supply available. 
  • Running the well is costly, and you want a way to save money delivering water to crops, livestock, your home, etc. 
  • You are trying to increase your energy independence, and solar is a good option. 

There are a few other reasons to consider connecting solar power to a water pump. However, the above three reasons are the primary choices. 

Water Pump
Water Pump

In this blog, we discuss:

  • The different options of connecting a solar panel to a water pump
  • The issues you face and options for mitigating those issues
  • Whether a battery backup system is needed for solar connected water pumps

How to connect a solar panel to a water pump?

The list of items you need to connect a solar to a water pump include:

  1. Solar panels — You will have to calculate the amount of energy needed to fill the solar batteries. That number will change based on the size of the pump and the number of direct hours of sunlight that the solar panel array receives per day.
  2. Solar Inverter — the type of inverter may change based on the size of the water pump to the size of the solar array and battery storage system. 
  3. Battery Back up Solar Storage System — Larger water pumps can draw a lot of energy, and that energy supply must be consistent, or the pump will fail. 
  4. Solar regulator — anytime you connect a solar panel to a solar battery, you need a regulator to keep the battery from overcharging. 
  5. A grid-tied connection — potentially — If the solar battery system is not large enough to power the pump 24/7, even on low energy production days, you will need to either shut the pump down or keep the unit tied to the local power grid. 

There are some configuration methods for the water system that can help decrease the load on the pump or make the process more efficient.

One of those ways is to pump the water into holding tanks that are above ground. You would set the pump to do that when the solar panels are producing the most energy.

With above-ground water storage, you are not pumping water against gravity; instead, gravity helps distribute the water, saving energy. 

Can I connect a solar panel directly to a water pump?

You could connect a solar panel directly to a water pump. It is not a good idea, though.

The erratic pulse of electricity produced by the solar panel will burn out the pump at some point. That process can take a few seconds to a few years.

The point is that connecting solar energy directly to a water pump shortens the life of the pump. If the pump’s design is such that it needs AC voltage, then the pump will burn out quickly.

Solar panels produce DC voltage and will burn out AC appliances in a matter of minutes. 

It gets worse too. Because the flow of electricity from a solar panel is not consistent — it peaks and wanes — causes the pump to heat up and then die. 

To fix these problems, you need a solar inverter that changes the DC voltage to AC voltage. A battery backup storage system also helps to even out the electrical current that powers the pump.

With a more consistent energy flow and AC voltage, the pump should run unaffected because it is connected to a solar array. If you are using a solar battery, be sure to add a solar regulator.

The regulator helps protect the batteries from overcharging. 

In short, you can connect a solar panel directly to a water pump; however, the result will not be pretty. 

How many solar panels does it take to run a water pump?

If you need to know how many solar panels it takes to power a water pump, you may be shocked that there is no standard answer. The issues are twofold:

  1. The wattage of the water pumps is not consistent. There are tiny pumps and mega pumps, and their power needs vary by the size of the pump. 
  2. The electricity of solar panels is not consistent either. There are tiny panels for tiny gadgets and large solar panels that form arrays. The wattage produced by different sizes of solar panels varies too. 

To figure out how many panels you need, you will need to know:

  1. The wattage of the solar panels
  2. The wattage of the pump
  3. The number of direct hours of sunlight the solar panel receives

Watts x hours of direct sunlight give you the total watts a solar panel can produce in a day. For example, if your water pump needs 3kWh of energy per 24-hour cycle, the solar array will need to produce 3,000 watts of energy. 

If each solar panel can create 250 watts of energy and receive 4 hours of direct sunlight, then the maximum energy each panel produces is 250×4 or 1,000 watts of energy.

That means you would need three 250 watt solar panels to produce the minimum amount of energy to run the pump. One thousand total watts per panel and 3,000 total watts to power the pump means 3,000/1,000 = 3 panels. 

That sounds simple enough, but the problem, and there is a problem, is that three panels will only supply the base level of energy needed.

Water pumps under a load may require different amounts of energy. So your solar array for the water pump may need to be more significant. 

Does a solar water pump need a battery system?

If you are wondering if your solar water pump needs a battery system, the answer might be complicated. Here’s why. 

If the water pump has a grid-tied connection, you don’t need a battery backup system. However, it will save you money every month to have a battery backup system over the use of grid-tied electricity.

The reason being is that a battery backup system allows you to harness all the energy your solar array produces.

That’s free energy (aside from the cost of the array and batteries) vs. the cost of buying electricity from the local utility company. 

The question is, “do you want to pay the local utility to run your water pump?” Generally, the answer is that you don’t want to pay the local utility, and with a battery backup system, you gain more self-reliance and energy independence. 

Sources 

How-To Solar Panel FAQ

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