Should I mount my solar panels flat or at an angle?

The impact of solar altitude angles

Ideally, you should mount your solar panels at an angle to maximise their power output. A photovoltaic solar panel will generate the most electricity when its face is perpendicular to the sun and the rays are able to hit the panel directly. The exact angle for ideal power generation will depend on the latitudinal position (the angle will be steeper if you are further from the equator) and the time of year (the angle will be lower in the summer and steeper in the winter). To demonstrate the substantial difference solar panel position can make, the graph below illustrates the outputs of two identical solar panels operating at the same time. One panel is lying flat, while the other is mounted at a 45 degree angle.

In this instance, the angled panel produced nearly 40% more power compared to the unit lying flat. Keep in mind that the difference between mounting angles will not always been this drastic, as time of year and latitude remain important factors.

Flat mounted panels considerations

Although an angled installation is ideal, it is not realistic for most mobile applications. Almost every solar panel installation on a caravan, boat, or 4WD will feature panels that are mounted flat against the roof. Panels will still function mounted flat, but several considerations need be made:

• Your solar panels will likely produce substantially less power than their rated output
• Panel performance will vary over as you travel north or south
• The seasonal angle of the sun will also cause your performance to vary
• Your panels will be harder to clean due to limited water runoff

How to compensate for flat mounted panels

Power loss from flat mounted panels will always be a factor in mobile applications; however, there are steps you can take to help compensate.

• Fit more solar panels if roof space and budget allow for it. You can make up for quality with quantity. Each panel might not produce its full potential, but having an under performing panel is better than having no panel at all.
• Get the most out of each panel by using an MPPT solar controller. The difference between a PWM and MPPT controller will also vary depending on environmental factors. For more information on MPPT controllers, click here.
• Some MPPT controllers (including all Enerdrive models) allow you to improve power availability by "overdriving" them with more solar panels. For more information on "overdriving" panels, click here.
• Add portable solar panels to your system. These can give you an extra boost to your solar production when you are parked and can be adjusted to face the sun.