Solar Drives (for Water Pumps)

What is a Solar Drive (for Water Pumps)?

Solar Drive Definition

A Solar Drive (for water pumps) is a type of electrical converter which converts the variable direct current (DC) output of a photovoltaic (PV) solar panel into alternating current (AC) that can be used by a local electrical water pump motor.

These drives are essentially solar-powered Variable Speed Drives (VSDs) providing alternating current (AC) motors with the required energy using standard photovoltaic (PV) panels, but also still allows for an AC input supply if required. In addition to this, the Solar Drive output frequency is adjustable in real time according to flow requirements as well as sunlight intensity.

Solar Drives (for water pumps) thus provides an energy efficient, environmentally friendly way to pump water for a variety of purposes. These Solar Drives have a long lifetime with low maintenance costs and allows users to immediately benefit from ‘free’ solar power.

For a more detailed explanation on this, please see our blog post: What is a Solar Drive (for Water Pumps)?

Solar Drive vs other Solar Inverters (Grid Tie, Hybrid, Backup)

All solar powered systems require a Solar Inverter to operate AC powered equipment and appliances. A Solar Inverter is a device that converts direct current (DC) generated by solar panels (or other alternative sources, such as batteries), into alternating current (AC) for use in industrial, commercial, and residential use. Key technical aspects differentiating Solar Inverters include classifying them as Pure Sine Wave Inverters, Modified Sine Wave Inverters or Square Wave Inverters, as well as classifications such as being Grid-Tied, Off-Grid or Hybrid solar inverters.

Solar Drives (for Water Pumps) on the other hand are unique when compared to these Solar Inverter types and applicable for more specific applications. Solar Drives are essentially basic Variable Speed Drives (VSDs) with a subset of VSD features, but with specific additional features and functionality applicable to Solar Water Pumping Systems, providing complete protection to the pump and controlling its functions, whilst using the free power from the sun to provide water at an affordable cost in areas with limited or no access to electricity.

Solar Drives are used independent from the grid, with no need or option for batteries, but with the option of AC input as a backup. Solar Drives thus serve as a fully automated Solar Water Pumping Solution, with typical applications that include irrigation, community water supply, fish farming and agriculture (in some cases Solar Drives are however also used to power other types of motors in remote locations).

For a more detailed explanation on this, please see our blog post: How do Solar Drives (for Water Pumps) Work?

Advantages of using a Solar Drive (for Water Pumps)

Solar Drive Benefits

A Solar Drive serves as fully automated Solar Water Pumping Solution, providing complete protection to the pump and controlling its functions, whilst using the free power from the sun to provide water at an affordable cost in areas with limited or no access to electricity.

In addition to this, the Solar Drive also offers a variety of other VSD features for motor protection such as over voltage, under voltage, phase imbalance, phase loss and over current. This solar powered solution also provides the added benefit (compared to using an AC input) of eliminating the potential voltage drop over extended lengths of electrical cable between the AC source and the motor (as well as the cost and possible theft of the cable).

Key benefits of such a Solar Water Pumping Solution include aspects such as:

Reliable alternative in regional and remote areas without electricity supply
Includes Variable Speed Drive (VSD) features
Low operating cost (cost savings)
Easy to relocate
Low maintenance
AC and DC power supply options

For a more detailed explanation on this, please see our blog post: Advantages of using a Solar Drive (for Water Pumps)

Other Solar Drive Use Cases

Other than the noted benefits of using a Solar Drive, these drives are also often used as Single-Phase to 3-Phase Converters and in some cases Solar Drives are also used to power other types of motors in remote locations (not as Water Pumping Solutions), utilising its basic VSD features together with its solar power capabilities. If you have a 3-Phase motor/device and do not have ready access to 3-Phase power, Solar Drives offer a workaround to get your equipment properly powered.

For more details on using Solar Drives as converters, please see our blog post: Single-Phase To 3-Phase Converters

Solar Drives are essentially designed to make use of this free power from the sun, as well as combining it with the benefits of using a VSD.

For a more detailed comparison between Solar Drives (for Water Pumps) and VSDs, please see our blog post: Solar Drive vs Variable Speed Drive

Solar Drive Industry Applications

What are Solar Drives Used for?

Solar Drives for surface and borehole pumps are ideal for use in South Africa which gets plenty of sunshine. Solar Drives (for water pumps) are a popular choice for converting an AC power supply pump solution to a DC power supply pump solution for watering livestock, crop irrigation, fish farming, industrial water supply, community water supply and even residential swimming and pool applications, etc. In some cases, Solar Drives are however also used to power other types of motors in remote locations), thus using it purely as a VSD with solar capabilities.

With Solar Drives essentially being modified VSDs, please also see our blog posts: VSD Industry Applications and: Use Cases – VSDs and Soft Starters

Please also see the following 2 ESKOM fact sheets on reducing costs using VSDs (since Solar Drives could typically also be used instead of the VSDs):

How do Solar Drives (for Water Pumps) Work?

Solar Drive Working Principle

Using the Solar Drive with solar input (DC from the PV array is supplied directly into the DC Bus), an array of solar panels generates the power and voltage required for the Solar Drive to drive the motor (using the VSD capability to convert the AC power supply to DC and back to Modified Sine Wave AC power again, adjusting the voltage and frequency as required). The Solar Drive converts the DC voltage input to a single or 3-Phase AC output (depending on model).

As the sun rises and PV voltage and current increases, the Solar Drive accepts the input (when the power is high enough) and will start the pump (PV array must be large enough to provide enough power). The maximum power point tracking (MPPT) ensures you get the best output power possible from your solar panels during daylight hours.

Solar Drives are used independent from the grid (with no need or option for batteries, but with the option of AC input as a backup). Solar Drive pump control functions typically include:

Maximum power point tracking (MPPT) for optimising PV array power output;
Going dormant (switching off) when radiation is too low;
Waking up (switching on) when radiation is high enough;
Going dormant (switching off) or Waking up (switching on) when high or low water level has been reached;
Under-load pre-warning (Dry run protection);
Auto-switch to grid supply (if available);
Other control and protection functions.

For a more detailed explanation on this, please see our blog post: How do Solar Drives (for Water Pumps) Work?

Solar Drives (for Water Pumps)

What is a Solar Drive (for Water Pumps)?

Solar Drive Definition

Solar Drive vs other Solar Inverters (Grid Tie, Hybrid, Backup)

TCGC distributes the following EMHEATER Solar Drives (for Water Pumps):

Single-Phase In/Out

Single-Phase to 3-Phase Converter

3-Phase In/Out