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Is Your Roof Fit For Solar Power?

By Kristy Hoare on in How Solar Power Works

Is Your Roof Fit For Solar Power?

Is your roof fit for solar power?

Have you ever experienced the frustration of entering a Levi's to get a pair of jeans - only to be turned away because they don't carry your size? Well, if you were to go shopping for solar power, you just might experience something similar - not all roofs are made for solar power.

But fret not, 'cause there is hope! As someone who wants to save up on energy costs you must be concerned how you can still make this happen. Our job is to give you a glimpse of some of the nooks and crannies of making your home solar-friendly.

Let's see how your roof measures up! Here are the main questions solar installers need to ask to make sure your roof is a good candidate. 

What's the size of your roof?

As a rule of thumb, you need at least 8m2 of free roof-space for installation.

With the power of Google Earth, it is now fairly easy to measure the area of your roof - even if you're not a solar installer. Once you have the size of your roof, consider the fact that multiple panels need to be installed on the roof. Some installers have a minimum size solar panel system they will install which is normally 6 - 8 solar panels.  The size of one panel ranges from 1.2 to 1.5 m2.

Lately, many installers in New Zealand have begun using micro-inverter solar panels, who may allow you to install just one panel, which is great news if you have a smaller roof. But bear in mind that the installation cost will be higher proportion of the overall cost if you install just one or two panels.

Is your roof facing north?

Typically, installers will have no trouble installing solar panels on roofs that are facing anywhere between east and west. North-facing roofs, however, are ideal as they produce more solar power. 

South-facing roofs, on the other hand, gain lesser radiation from the sun. Installers may be able to tilt the panels off the roof so they become more north-facing, but if you are concerned about aesthetics you might not want to go there!

What's the pitch of your roof?

This question about the angle of your roof is hardly a deal breaker. The optimum pitch is between 25 and 30 degrees (in New Zealand) but roofs between 10 and 60 degrees work just as well. So why should you worry about this?

Well, remember that we are trying to generate power by exposing the panels to sunlight, which is in abundance throughout the day. A lower (or higher) angle only means that the exposure to sunlight is a fraction less, resulting in an even smaller loss in power. Some might call is negligible.

If your roof is completely flat or has a pitch that is less than 10 degrees, most installers will suggest tilting the panels to enhance the angle, but once again, the case for beautification and aesthetics emerges - it may look a tad bit ugly. In such cases it is perfectly fine to install panels that are completely flat, but take into account that there is no self-cleaning mechanism despite rain for flat panels, and therefore, they may require regular cleaning.

For roofs over 60 degrees, the panels can be tilted from the lower-end to bring them closer to the optimum level.

Does your house get some shade?

Even a small amount of shade (like from a neighbour's chimney or a tree) can lead to a serious decrease in the amount of power the system produces.

Shading can cause a disproportionate loss of power as opposed to the area that is shaded. For example, if a solar panel array is getting 10% shade, it may lead to a 50% loss in power.

Some installers are able to figure out exactly how much power you might lose based on that tree or that other object obstructing your solar power system. Based on their calculations, they may suggest placing the panels on another part of the roof - even another roof face. It may be worth replanting a tree or moving the antenna on your roof to ensure you get the full benefit from using your system.

Remember, this is your decision as most solar installers can still install a system that suffers from shade. You are someone who has done their homework, so make sure you ask them enough questions and remove all doubts before you make the final call.


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