How Much Sun Do Solar Water Heaters Need?

So you’re interested in installing a solar water heater, but you lack a south-facing roof. You may have heard that solar panels require direct, southern exposure and all-day sun. Does this mean solar hot water is not an option for you?

Not necessarily.

While solar electric (PV) panels require a lot of sun to operate, solar thermal panels are much more forgiving. Solar water heaters are incredibly efficient, typically converting 60-80 percent of the energy they receive from the sun into usable heat. This means that even under less-than-ideal conditions they can still make hot water for your home.

While a full southern orientation is best, panels facing up to 90 degrees east or west of true south will perform nearly as well. If your roof faces east or west, chances are your home is still eligible for solar water heating.

Of course, orientation is just one factor affecting the amount of light hitting your panels. Ideally, you’ll want to avoid placing your panels where they will be shaded by landscape features such as buildings, trees and hills.

Your local climate and air quality are also factors to consider when determining the proper size for your solar water heater. Sunny days offer greater energy potential, but don’t despair if you experience frequent cloudy or smoggy weather. Most likely, your hometown is no cloudier than the average city in Germany, which has one of the highest percentages of installed solar per capita in the world.

One last thing to consider is the angle at which your panels are mounted. Best practice for optimal panel performance is to mount solar panels at an angle equal to the latitude of the site. However, there are other practical considerations to take into account when determining the tilt of your solar collectors. When the panel angle differs substantially from the roof angle, it can result in an odd-looking installation. Rack-mounted panels are also more susceptible to wind damage. Most rooftop solar panels are mounted at the same angle as the roof for these reasons. While this might not be the ideal angle for maximum solar energy collection, most roof angles allow for adequate performance.

When we assess your home for solar, we take all these factors into account and more to determine the ideal size for your solar water heater. We also analyze your current energy bills and identify all state, federal, and municipal renewable energy credits and grants for which you may be eligible. That way, you’ll know in advance not just whether a solar water heater could work for your home, but how much it could save you.

To find out for sure whether you receive enough sunlight for solar water heating, contact us today for your free solar analysis and estimate. One of our trained technicians will evaluate your situation free of charge.