SunCentric Pool Water Pumping

A brief introduction

©2003 Conergy

There are many swimming pools that are beyond the reach of power lines in Latin America, the Caribbean, the Mediterranean, and all over the world. Imagine relaxing at the pool with a noisy generator running! Solar pumping is naturally appropriate because pool filtration is needed most during the periods of algae growth, which correspond to sun intensity. On-grid pool owners can use solar pumps too, in conjunction with solar water heating. The speed of the pump is synchronous with the the heat absorption, which makes a harmonious match.

Solar pool pumping is economically feasible if attention is paid to the energy efficiency of the system as a whole. In that way, it is no different from any of our other solar applications. Here are some general guidelines for system design.

Rules for energy-efficient pool pumping

• The normal requirement of a pool pump is to pump the entire volume of the pool per day. Choose a pump that will not greatly exceed this daily volume on a sunny day.
• Choose the filter carefully. Its back pressure imposes the biggest load on the pump. A large filter will impede the flow less than a small one. Cartridge filters impose less resistance than sand filters. The filter maker's specifications will show the back pressure vs. flow rate. Two filters can be piped in parallel, to split the flow and cut the back pressure in half.
• Use large sized pipe to reduce friction. For a typical residential pool, this generally means 2inch pipe instead of 1.5inch pipe.
• Avoid sharp 90° elbows where possible. Instead, use long-radius elbows, 45° elbows, or flexible hose.
• Consult friction loss charts for pipe and fittings, then calculate the total Choose a pump that uses the least power for the flow and pressure required.

The SunCentric™ Solar Centrifugal Pump

Conergy SunCentric DC pumps are built with efficiency in mind. They use significantly less power than AC pool pumps to produce the same pressure and flow. If your pressure requirement is low, choose one of the specialized low-lift models. The power saving will be greater. SunCentric can run from a battery system or directly from a solar array. To protect the pump from debris, an optional basket strainer is available.

Retrofitting an existing pool system

In a retrofit situation you may not have the opportunity to follow all of our efficiency rules, but there is hope. If the owner feels that a reduced rate of flow is acceptable, then the power requirement will be reduced drastically! This easy example illustrates the principle-If the flow were to be reduced by 50%, then the back pressure imposed on the pump will be reduced to only 25%. Theoretically, the power required to pump 1/2 the flow at 1/4 the pressure will be 1/8, or 12.5%! Using the same arithmetic, a more reasonable flow reduction of 25% would reduce pressure drop to 56% and the power requirement to 42%. If a pump is selected that is efficient at this reduced range, then the theoretical saving can be realized. If the pump is more efficient than the original pump, then the saving will be greater.

Supplemental methods of pool management

Modern pool technology provides methods of pool cleaning using chemistry, electro-chemistry, robotic pool cleaners, and more. These methods can be used to reduce the filtration pumping requirement, thus allowing the use of a lower rate of flow. Consult with an authority on pool sanitation to learn how these methods can reduce pumping requirements without compromising the safety of the pool.

Using a backup pump

It is easy to install a SunCentric pump parallel to an AC pump. The AC pump can serve as a backup or to supply additional flow on cleaning day. Connect the pump intakes together. Install a low-resistance check valve at each pump's outlet, then connect the check valve outlets together. Either pump (or both) can be turned on, with no need to touch any valves.

Long-term economy

Solar pumping is a long-term investment. Most photovoltaic solar modules have a 20 year warranty, and a life expectancy beyond 30 years. The SunCentric pump can also last that long. It will far outlast a cheap AC pool pump because of its high industrial quality and lower rotational speed.