Themo Dynamics Ltd. - Solar Pumps

Solar Pumps

PV Powered Low Flow Solar Pump

System Description

The sun powers the Thermo Dynamics Solar Pump - no batteries, no high-voltage electricity, no engine consuming gasoline or diesel fuel - only harmless, low-voltage, solar-generated electricity, eternally available and pollution free. The Solar Pump system utilizes a positive displacement vane pump driven by a DC motor. A photovoltaic (PV) module drives the DC motor with a linear current booster that provides maximum performance at all solar irradiance levels.

Product Use

The Solar Pump is the perfect pump for a solar water heater. For most solar water heaters for single-family homes a 10 - 20 watt PV module is adequate. There are no electronic controller and temperature sensors to install, with none of the associated high-voltage wiring. The PV module provides the correct power to the Solar Pump to circulate the solar collector fluid when there is heat in the collectors. The flow rate is always at the right value to maximize the delivery of heat from the solar collectors at the highest temperature, without sacrificing thermal performance. Installers love the Solar Pump - it is so much easier to install than the controller-based systems. Homeowners appreciate the fact that ALL the energy used to produce their solar heated water comes from the sun, and none from the electrical grid that delivers electricity generated by environmentally damaging technologies.

The Solar Pump is also the perfect pump for low-flow irrigation and general water pumping. It can be used to pump most liquids, including water and water/glycol solutions.

System Operation and Advantages

The Solar Pump will run 2000 hours per year in mid-latitude countries. Assuming your application requires a 35 watt PV module you save 200 kilowatt-hours of purchased electricity each year by using the Solar Pump, or 2000 kilowatt-hours over the 10-year warranty period of the pump. These savings will more than cover the additional costs of the Solar Pump relative to a standard "plug-in" pump. Not only is it economical to use the Solar Pump, but by using solar energy you reduce the pollution for which you are responsible by using a grid-connected pump. To produce 2000 kilowatt-hours of electricity in a modern steam power plant will result in two tonnes of carbon dioxide emissions into the atmosphere!!

Consider all the advantages:

quiet operation
self-priming
life expectancy of over twenty years
ten-year limited warranty
no high-voltage electrical connections
no certified electrician to install the pump
no municipal electrical permit required
no high-voltage electromagnetic fields

The Solar Pump uses a proportional control strategy, achieved by the variable output of a PV module. The PV module drives the DC motor through a linear current booster to ensure maximum performance at low solar irradiance levels. With the Solar Pump flow rates range from 0.4 liters/minute (0.1 USGPM) with Model #1205 at zero pressure rise to 4 L/m (1 USGPM) with model 40 at 700 kPa (100 psi). Pumping with the Solar Pump begins at low sunlight conditions - even at one-fifth of a full sun (200 W/m2).

System Configuration

The Solar Pump consists of:

sliding-vane brass pump
built-in strainer (100 mesh/125 micron)
DC motor c/w mounting feet
pump-motor V-band coupling
3-ampere linear current booster

Weight = 3.9 kg (8.5 lbs)

PV Module

A 10 to 50 watt PV module powers the Solar Pump, depending on the flow and pressure requirements of your application. A PV module with Vmp of 16-17 volts is required, which is typical of most modules with 36 crystalline cells or 13 amorphous cells. Tell us your flow and pressure requirements and we will specify the correct pump model number and PV module.

Linear Current Booster

A linear current booster (LCB) matches the power delivery of the PV module to the DC motor under varying sunlight condition. The LCB can handle up to 3 amperes of current from the PV module. At full sun the PV module runs the motor at rated speed. At lower sunlight levels the LCB transforms the voltage into current to start the motor and keep it running at low RPM. The motor runs at reduced speed at lower sunlight levels providing a flow rate proportional to the intensity of the solar radiation.

Pump Description

The pump is a brass body, vane-type, positive displacement pump. The pump has special clearances and seals for high temperature protection up to 100°C. It has a maximum output pressure of 700 kPa (100 psi). The pump has 3/8" FPT inlet and outlet ports, and comes equipped with standard compression fittings for 3/8" OD tube (9.53 mm OD).

The Solar Pump is engineered for long life and super efficient operation to enable you to use the lowest possible power PV module. The Solar Pump is equipped with a built-in stainless steel strainer. No parts are subject to corrosion - all wetted parts are stainless steel, brass or carbon. Each Solar Pump is backed by a 10-year limited warranty.

The Solar Pump is a positive displacement pump, which means there is no waste of time or money on equipment to purge air from the circulation loop. It is also self-priming, with a maximum suction lift of 2 meters (6 feet).

DC Motor

The Solar Pump - motor, because of its efficient design, is larger than pumps designed to operate at 110, 220 or 240 volts. We use permanent magnets, whereas standard motors use electrical coils and electric current to create the magnetic field. This wastes precious electricity. However, permanent magnets are heavy and bulkier than the equivalent electrical windings. To produce the torque required to boost the pressure of the pumped liquid we use a heavy-duty, large-diameter armature with thick copper windings to reduce parasitic power consumption by the motor. The result is amazing - even in very weak sun a motor that produces enough power to start the pump, power that is produced in the "greenest" of all possible methods. The motor is brushed, with brushes designed to last longer than the motor itself. The brushes will never require replacement when the motor is driven by a PV module under 50 watts peak power.

Solar Pump Curves

Model	Flow Range (L/min)	Flow Range (USGPM)	Fittings	Integral Strainer
P24070	0.3 - 2.4	0.1 - 0.6	3/8" O.D. Compression	yes
P50140	1.0 - 5.0	0.3 - 1.3	1/2" O.D. Compression	yes
P118330	2.0 - 12.0	0.5 - 3.2	5/8" O.D. Compression	no

To assist you in choosing the most suitable Solar Pump for your application, please go to our Solar Pump Selection Guide or download a PDF version of the guide. DOWNLOAD Solar Pump Selection Guide

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