There are some rules of thumb that will tell you how many solar pool heating panels you will need. The answer varies based on a few assumptions, and the number of panels is determined based on several factors. Don’t assume that your neighbor’s system will perform the same way for your home, and your budget is also a consideration.

Assumptions Used To Determine Solar Pool Heating Panel Sizing

We need to set expectations properly from the start, so answering a few questions is key to sizing a system appropriately:

• How long do you want to extend your swimming season. Do you expect year-round swimming, or do you just want to extend your season? Most people request year-round swimming, but then realize it is impractical and not necessary given the coldest days we experience here.
• What temperature are you generally shooting for? Note that this may change by season. Most people will throw out a number rather arbitrarily (85ºF seems to be popular). In reality, pool comfort is relative to the outside air temperature and weather, and a wide range of temperatures can be comfortable for swimming.
• Are you planning on using a pool solar blanket and an automated solar controller? A pool blanket can reduce your investment in solar panels and provide faster heating and higher ultimate temperatures. An automated solar controller will optimize the operation of your system and provide convenience.

Factors That Affect How Many Solar Pool Heating Panels You Need

There are several factors to consider, and the importance of each factor may vary. Some of the major factors are:

• The surface area of your pool. The volume is not particularly important, as most heat is lost from a pool’s surface, and we are working to overcome heat loss with any heating system.
• The orientation and roof pitch where the panels are intended to go.
• Shading issues that may reduce the effectiveness of the system.
• Exposure to wind (pool and panels).
• Screened or unscreened pool.
• Available flow rate from existing equipment.

Ball Park Estimate for Solar Pool Heater Sizing

If there is one factor that can be used to size a solar pool heater and ensure customer satisfaction, it is matching the surface area of the solar panels to the surface area of the pool. We shoot for 100% for orientations of east, south, and west. If you size your solar pool heater on this basis for any typical roof in Southwest Florida, you will get pretty close to what we consider satisfying performance for year-round swimming on days where people are actually likely to swim (i.e. the outside air temperature is conducive to swimming).

A very common pool size in the area is 14’x28′, meaning you need to match a surface area of 392 square feet. If you are using 4’x12′ panels (48 sq ft each), you need about 8 or 9 panels. From there we can make adjustments for ideal or sub-optimal orientation, shading, and the other factors listed above. Of course, if you don’t have enough roof space, we may be constrained, but even an “undersized” system can provide a satisfying customer experience. This is especially true for the best solar panels that harvest the most sun under sub-optimal conditions (ours, of course).

By using the 100% coverage rule of thumb, and making adjustments based on site conditions and experience, we can tell you how many solar pool heating panels you need to heat your pool. As you might imagine, bigger is always better. There is a point of diminishing returns, however, and systems need to be suitably matched to your existing equipment (unless you plan to upgrade your pool pump, filter, or plumbing). Larger solar pool heating systems tend to help your pool reach the maximum temperature more quickly each day, but the maximum temperature does not go up drastically with more panels because they become less effective as the pool gets warmer. If you plan to use a pool solar blanket, a larger system may be less important.

To be safe, you should probably consider the advice of your solar professional after an evaluation of your site. The 100% coverage rule will get your pretty close, but a more detailed look is always a good idea. We can perform an aerial photography analysis of your site using 3D computer modeling prior to an on-site evaluation, and tweak the system sizing according to any findings that would affect your pool heating satisfaction.