This article reveals how to manage your solar water heater’s tilt angle and orientation during installation. These factors are important. They ensure your solar panels receive maximum amount of solar energy through different seasons, especially winter, when there’s little sunlight. With maximum efficiency, solar collectors can be smaller. This means they take up less space and require a lower setup cost.
If you’re living in the northern hemisphere, your solar collectors should be tilted southward. The tilt angle is 15 degrees plus the latitude of the installation site. This is the ideal configuration that allows you to collect maximum sunlight all year round. For example, Arizona has latitude of 33 degrees. Therefore the tilt angle of your panel should be 48 degrees in order for it to harness maximum energy.
But many homeowners choose to conform the tilt angle to the inclination of their roof. They are concerned about the aesthetics of the installation. Although we will not achieve an optimized configuration in an engineering point of view, such setup serves the user’s needs and wants after all.
Fortunately, solar collectors with tilt variations that fall within 20 degrees (either direction) will not suffer serious loss. In fact, tilting them some 15 degrees northward from its optimum angle can have its advantages. During summer, water will not overheat and during winter more hot water is produced.
Similarly, tilting your heat collectors southward (away from the optimum tilt angle) can result in more overheating during summer and less hot water during winter. Ideally, the tilt angle can be adjusted according to the seasons. But the hardware required to implement this setup may end up as an ugly structure of metal and joints that displease homeowners. There will also be more moving parts to be maintained.
When orientating your heat collectors, you should ideally point them to true south. As compared to photovoltaic panels, heat collectors are more forgiving. Orientations of 15 degrees off true south still enable solar collectors to receive most of the solar energy. Beyond this tolerance, the effectiveness of the heat collector decays quickly.
You may often be forced to make a choice between an east-biased or west-biased orientation away from true south. Perfect orientations tend to be impractical at times. If you’re in this fix, choose the west so heat collectors can be exposed to more heat as a result of higher ambient temperatures in the afternoons.
As you line up your compass to find true south, remember that it is pointing to magnetic south instead. Corrections must be made to locate the optimum orientation. To do this, you need to compensate for the magnetic declination of your site.
Finally, as you are evaluating the installation site, remember that shadows cause your heat collectors to be drastically less efficient. Although solar water heaters are not as sensitive to shading, it is good to place them in an open, unobstructed location from 9am to 3pm so they can be exposed to the maximum amount of sunshine during this critical period. Using a standard shade analysis tool like a solar pathfinder, you can make it easier for yourself to evaluate the shading condition of your location.
Last modified: November 10, 2020
