When we hire a new employee, they often come with a lot of the same misconceptions about solar energy that our clients initially have. Our relatively new sales assistant, Christie, asked me this week about a topic that comes up quite frequently: Solar pool heating panels make the pool pump work harder.
It might seem logical, but it’s a myth!
Here are the reasons it comes up in our day to day consultations:
- Sketchy competitors say that another company’s solar panels cause more back pressure and this will somehow blow up their pump.
- Pool builders are afraid that solar panels will increase the pressure in the system, which they mistakenly believe will cause more energy use.
- Because we are lifting water to the roof, homeowners think the pump must work harder because it has more force against it.
To understand this issue better, we need to first define “work.” Work, the term in physics, refers to force times distance. When most people think of “more work,” they think of something that is harder, which must use more energy (electricity in this case). That’s true — if more work is done, more electricity is needed.
But the truth is that when a pool pump encounters a higher pressure against which it must push, the amount of water that is moved (distance in a given time) is reduced. In the case of a single speed pump, it only runs at a single RPM, and does essentially the same amount of “work” regardless of how much pressure exists in the system. The force increases, and the distance (or speed if talking about time) decreases. The “work” remains the same! For a given pump speed (measured in RPM), the amount of work it does, and energy use, will remain essentially the same.
From a practical standpoint, all that matters is whether your existing pool pump is capable of pumping water through the solar panels and back to the pool. Here are a few truths to debunk solar pool heating pump myths:
- Properly designed solar pool heating systems only add a few pounds per square inch of pressure to your pool plumbing. If the pool is designed correctly, and maintained and works properly, the reduction in flow will be negligible.
- There will be a small reduction in flow in your overall system, which means that your pump will need to run for a longer period of time to circulate the same amount of water. Again, since the reduction in flow is very little, it is generally not necessary to increase your pump run time (which would, in fact, increase “work” and pumping costs). Most people run their pumps too long anyway.
- Pool pumps that are “deadheaded,” meaning they have reached their maximum pressure rating or close to it, may be damaged. Again, in a properly designed and maintained system, this in a non-issue.
Solar pool heaters don’t blow up pumps, and they don’t make pumps work harder. The next time someone tells you a pool pump needs to work harder to overcome higher pressure, you will be better equipped to debunk the myth!