How to Choose Solar Panels for Well Pump?

If you depend on a well pump for your water needs, it would account for a big chunk of your grid energy consumption.

This also means the running cost is substantial. Is there a way out of this? Can you run a well pump without incurring a high cost?

When you are searching for cheaper energy alternatives, the most obvious one is solar power. This leads us to the next question. Can we run a well pump on solar energy?

The good news is you can. All you need is an inverter to convert DC to AC, just as in the case of any other solar device. If you haven’t yet got the pump, you can go in for a DC pump to keep things simple.

Want to know more? Read on.

This article will answer most of your questions on the topic such as the viability of this idea, how to pick the correct solar panels, how to install a solar well pumping system, and how to maintain it.

Table of Contents

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What is a solar well pump?

While a standard well pump draws energy from the grid to run, a solar powered pump uses the sun’s free energy to run the show. The well pump works the same in either case.

In a solar well pumping system, the device is linked to the photovoltaic array in the solar power system to run the motor of the pump. As the motor runs, the pump will draw water from the well.

Well pumps are of three types.

Surface pumps
Floating pumps
Submersible pumps

Here is an overview of the three types.

Pump type	Position of pump	Position of PV panels	Position of controller	Ideal when	Remarks
Surface pump	Above water level	Near the pump	Near solar panels	Well is shallow	Suction pipe needed
Floating pump	Floating on water surface	Near the well	Near solar panels	Well is open	Flexible pipe needed to adjust to changing water levels
Submersible pump	Below water level	Near the well	Near solar panels	Well is deep	Powerful pump needed

All three types of well pumps can be run using solar energy.

Using solar energy to run well pumps

If you are still unsure whether this is possible, rest assured, you can.

Besides categorizing solar well pumps based on the position of the pump, they are also classified by the kind of electric power they use – Direct Current (DC) or Alternating Current (AC).

Let’s take a look at them in detail.

AC well pump (run using converted solar power)

If you want to go solar with an existing pump, this is your best option. Most pumps running using grid energy are AC pumps. Converting well pump to solar is a reality.

However, to integrate an AC pump with a solar power setup, you need an inverter to convert DC to AC. If you are confused, don’t worry. Here is more explanation.

Solar panels convert the sun’s energy into Direct Current or DC. But grid energy is Alternating Current or AC. If the pump has been working on grid energy and you want to continue running the same pump with solar panels, installing an inverter is essential. The function of the inverter is to transform DC to AC.

Converting well pump to solar would be the right choice for cost-saving as buying an inverter is more affordable than changing the pump. However, the solar upgrade will be more expensive.

DC well pump (run directly using solar power)

In case you are shopping for a pump together with a solar panel system, opting for a DC pump can help in avoiding the need for an inverter and thus reducing the cost.

A DC pump is well-equipped to use the DC power generated by solar panels directly, simplifying the arrangement. Remember that this is possible only if you don’t already have a pump in place. Moreover, DC pumps are more expensive than AC pumps.

However, DC pumps have a longer lifespan and are higher in efficiency.

Hybrid solar pump

Water pumps are available in the market that can work on both AC and DC power. As DC power supply from the solar panels is not available round the clock, you may have to use grid energy as a backup. A hybrid pump can function smoothly without hiccups in such situations.

Unfortunately, this convenience comes with a major disadvantage in the efficiency of the pump. Hybrid pumps come with a poor performance tag.

Advantages of a solar well pumping system

All the reasons given for going solar apply to well pumps as well. And there are a few more specific to this.

As well pumps are often used in remote locations, the grid energy may not be available. Using solar energy helps in getting the work done equally well.
If you are keen on off-the-grid living, this is a good choice to ensure water supply.
Solar energy can be used as a backup for grid-powered pumps during blackouts.
As the sun’s energy is free, the cost of running is virtually zero. This means huge savings on energy bills.

Components of a solar well pump system

The main elements of this setup are of course the water pump and the solar panels. However, there are other parts to link them up and make them work together seamlessly.

Let’s see each one of them in detail.

Water pump: This is an electrical device that includes a motor. As the motor runs, water is drawn from the well and brought to the surface. A pump will have an inlet pipe that is dipped in the water in the well and an outlet pipe to fill the pumped water in a storage tank.

Water pipes: These do the vital job of transporting water to the pump and the storage tank.

Solar panels: The capacity of the solar panels needs to be chosen based on the requirement of the pump. The panels should be installed to take full advantage of the sunlight available but at the same time, they should be as close to the pump as possible to avoid lengthy wires.

Maximum Power Point Tracker (MPPT): This is a component of all solar devices. It controls the energy generated to suit the device. Maximum power point is achieved through ideal voltage, maximizing current, and minimizing losses.

Solar inverter: This is a vital part of a solar power system to convert the DC power generated by solar panels into AC. If you are teaming up the solar system with a DC well pump, this can be avoided.

Solar battery: Being dependent on the sun for energy, a solar device is incapable of generating energy when the sun is not shining. If you want a 24×7 power supply, adding a battery to the setup will help overcome this shortcoming.

Note: Though not a component of the solar well pump, a storage tank is essential to hold the water pumped from the well.

Installing a solar well pump: A step-by-step guide

Unless you are knowledgeable and experienced in setting up a solar pump kit, it is better to leave this to professionals. This process needs technical know-how to ensure no glitches while running the pump.

A point to note here is that you can skip the steps of pump installation if you are working with a pre-existing AC well pump.

1. Planning stage

This step involves assessing what you have and want. It is more about evaluation and research. You need to find answers to these points.

Availability of sunlight in the location. You can figure this out by searching for average solar irradiation in the area.
Identifying the ideal position for solar panels
Figuring out the perfect orientation and tilt of solar panel installation
The best position for installing the solar water pump and MPPT controller
Length and diameter of water pipes and quantity of electric cables needed
The maximum rate of flow and expected loss due to friction
Expected elevation head and dynamic head (height of the storage tank determines how far the water needs to be pumped)

2. Choosing the correct solar pump kit

Not all wells are the same and neither are all pumps the same. Since you already have the well ready, you need to ensure that the pump is a suitable one.

Here’s a checklist ready for you.

The pump should be selected to match the kind of well you have. Additionally, you should also take into consideration the location, flow rate, and total dynamic head.

Most solar pump manufacturers offer software to help you pick the right pump.

3. Selecting a suitable solar power system

If you are shopping for a DC pump, it comes bundled with the right-sized solar panels to provide power. You will also find all the components you need to install the solar system including solar panels, mounting equipment, and other elements such as inverter, controller, and battery.

However, if you are converting well pump to solar, you may have to do most of the calculations and work on your own. You can always get help from a solar technician to figure out the capacity of the solar panels you’ll need to run the pump.

One of the simplest ways to find the right solar system for your pump is to match the wattage of both. For instance, if the wattage of your pump is 200W, you can either choose a single 200W solar panel or 2 100W ones, or even 10 20W panels. You need to make sure that it adds up.

You can either fix the mounting structure on the ground or a pole. Once this is ready, all you need to do is mount the panels.

You also need to ensure that the orientation and tilt are perfect for maximum exposure to the sun.

4. Connecting various components

In a solar powered pump system, these are the basic connections you need to pay attention to.

Solar panel to MPPT controller
MPPT controller to pump
Grounding of all exposed metal casings

Most manufacturers provide detailed guidelines to help you with this. You just need to follow the steps.

5. Installing MPPT controller/Inverter/Battery

In the case of DC pumps, there is no need for an inverter. This is needed only for AC pumps.

The MPPT controller is typically mounted on the framework of the solar panel. In case it is mounted on a pole, the controller can be fixed to the mounting pole. This remains the case, irrespective of the configuration of the solar panels.

Note: As the controller will be exposed to the elements, you need to follow the manufacturer’s instructions regarding waterproofing requirements. In most cases, a minimum requirement of IP56 needs to be followed.

The inverter and battery are usually kept inside but not too far from the solar panels.

6. Pump and pipes installation

The installation guidelines differ depending on the kind of pump you have chosen. You will find here setup instructions for submersible and surface pumps.

Installing submersible pumps

Remember not to install the pump on the bottom of the well. The pump should be about a meter above the bottom.
Take care not to keep the pump too close to the water surface. It should be installed lower than the drawdown level to avoid running it dry.
Including a water-level sensor will help in avoiding the dry operation of the pump.
The pump may be fixed using a cable connected to the cap of the borehole.

Follow these tips during pipe installation.

Keep the discharge pipe screwed to the pump for support.
Attach a no-return valve at the end of the discharge pipe, immediately above the pump.
Attach a gate valve at the other end of the discharge pipe above the exit point of the well.

Installing surface pumps

You will need a supporting base to install the pump. A concrete structure is preferred for this.
Keep the installed pump covered with a metal covering to protect it from direct sunlight.

Note: Raising the height of the pump will help in reducing vibrations when it is working. Vibrations may hamper the pumping mechanism.

As the pump is kept above the water level, a suction pipe is essential to bring the water up. Here are a few suggestions while installing suction pipes for surface pumps.

The pipe should be of minimum length.
If a pipe longer than 3 meters is used, you should bury it to avoid heating up due to friction. Hot water can harm the pump.
The suction pipe needs to be kept lower than the pump inlet to avoid trapping air.
Keep the exposed end of the pipe clear of debris to avoid blockages.
The end of the pipe discharging water shouldn’t have bends.

Maintenance of solar well pump

As long as you have installed the solar pump correctly, you shouldn’t face any trouble in its maintenance. Most of the maintenance activities around a solar water pump will involve solar panels.

In case you are not familiar with solar panel maintenance, here are the steps.

Clear the dirt, dust, and debris accumulated on the panel surface.
Periodical inspection of electrical connection is recommended.
In case of any loose connections, fix them without delay.
Check and ensure that there are no physical or mechanical impairments.

For proper maintenance of the pump, it is ideal to follow the manufacturer’s instructions. The maintenance producers are not the same for all well pumps in the market.

You also need to check on the pump controller to ensure it is not damaged in any way. It has to be kept clean. Check the wiring to ensure there are no damages to the cables and that connections are in order.

Backup for solar well pump

When you are completely dependent on the pump for your water needs, it makes sense to have a backup. You can choose a solar battery as a backup or keep the pump connected to the grid using a net-metering arrangement.

When choosing a battery for your solar pump, you should find answers to the same questions you asked earlier when choosing solar panels.

How much solar energy is needed to run the pump?

You should choose a solar battery with the same voltage as the pump. For a 12V pump, a 12V battery would be ideal for backup. For a 120V pump, you can choose a 120V battery as backup.

Another choice before you for backup is a hand pump. Though it is hard work to draw water using a hand pump, you can rest assured that you don’t have to manage without water. This way, you can avoid using grid energy.

Bottom line

You should first figure out your requirements before going shopping for a solar well pump. If you already have an AC pump, you can still install a solar panel and make it work on solar power. All you need is an extra inverter.

However, if you are yet to buy a pump, it is always better to choose a DC pump. This can bring down the cost of the setup for you as you can avoid installing an inverter.

Using the free energy from the sun to power your well pump makes sense. In the long run, you will be saving substantially on your energy bills besides ensuring the availability of water during blackouts.