Solar pool heating collector vs. PV
Heating the pool water using the suns' energy extends the swim season using a friendly, ecological heating system. This is why, in recent years, this heating method has become so popular and is widespread on rooftops throughout the world. When discussing solar heating for swimming pools it should be emphasized that we are talking about solar pool water heating using the sun's free energy not using PV collectors that produce electricity using the suns' energy. This article will review the significant differences between the two types of solar panels.
A solar pool heating system is comprised from four main elements - solar collector, circulation pump, plumbing and a controller. The process is completely automated: pool water is circulated from the pool by the pump through the filter to the solar collectors. Water reaches the bottom of the collector and flows upwards through the individual riser tubes. Water is heated by the sun while in the tubes and returns to the pool. This process repeats itself and continues as long as the circulation pump is working or until water has reached the desired temperature.
The process of producing electricity using solar energy is done by a photo-voltaic cell (PV) manufactured from silicone and based on semiconductors that create an electrical field. Sun light hits the cell, causing a discharge of electrical energy. The electrical energy is stored and then used or sold. What was once considered the sole "madness" of ecological aware environmentalists has become a popular household solution; carrying with it the green ecological agenda, PV solar collectors are a great money saver whether fully or partially producing electricity for domestic use. That said, for pool heating, this process is not as relevant. Why? PV for electrical production converts 15%-20% radiation to energy. Meaning its energy efficiency is low - 85% of the sun's radiation is lost. Whereas the solar thermal collector is able to convert 70%-80% of the suns radiation to heat, meaning, it is far more energy efficient and its heat production is powerful.
Another disadvantage for heating pool water using a solar electrical system is the high fabrication costs. PV is manufactured with Aluminum which is far more expensive than manufacturing a collector from polymer which costs a tenth of fabrication costs for square meter for a collector that yields 4 times the heat! To summarize: heating pool water using PV panels is not effective (low energy efficiency), not economical and carries high costs.
For a family that owns a PV rooftop system and is considering installing a solar pool heating system we recommend installing the solar pool heating collectors on the roof next to the PV collectors, which many times do not cover the entire roof. Another option is installing the solar pool heating collectors next to the pool or on a pergola to save space and shade the pool.