7 Factors To Consider If You're Fitting Solar Panels
Manan Singh - Solar Researcher
Last Updated: October 10, 2021
Last Updated: October 10, 2021
If you’re planning on harnessing the power of renewable energy, then fitting roof solar panels has to be at the front of your mind.
Why? Because they are a fantastic source of sustainable energy that can be used wherever you live. Plus, there are some great financial incentives to help with installation and provide you with the means to earn from the electricity you produce.
As you are here, I’m guessing that you’re already considering solar energy, but have some questions about the installation of roof solar panels on your property.
So with this in mind, we put together this guide to make it easier for you to get a big picture of what you need to look at when installing solar panels on your roof.
Something I forgot to mention. If you’re still not sure about solar energy and want to do a thorough analysis, please check out this article into the pros and cons of solar energy. It’s literally a warts and all overview.
Not all roofs are born equal:
1. Is it made of suitable material?
2. What’s the roof’s condition?
3. Is the roof old?
4. Which way does it face?
5. Is it shaded?
6. What is the roof angle?
7. How big is your roof?
So, with this in mind, let’s look at these factors in more detail.
Roofs are made of various materials, and for solar panels they need to be strong and durable. Some of the best materials include:
Some of the not so durable materials that are ok but may need strengthening include:
Roof materials that aren’t good for solar panels and should be avoided include:
If your roof is old and will need to be repaired or replaced in the next 20 years, then you’ll need to do any necessary repairs before installation. Most solar panel arrays have a lifespan of between 15-25 years.
If you put solar panels on a roof that will need repairing or replacing before, then it’s going to be an expensive job to remove and then put them back. In fact, in most cases, it would be easier and more cost efficient to start again.
If you’re not sure about the integrity of your roof, it’s advisable to ask a roofer for their advice.
Similar to checking the age of the roof, it’s important to inspect the roof to make sure that it’s going to be strong enough to bear the load and also if there any hidden repair issues lurking around.
Some things to look out for are missing tiles, water damage, rotting beams and holes. Even if there isn’t anything obvious showing, it’s worth having a chat with a roofer to get their opinion.
Although they will work in most daylight conditions, positioning them to maximize the sun’s journey through the sky will help to optimize the generation of electricity.
Ideally, in the northern hemisphere, south facing solar roof panels are recommended but often this isn’t possible because of the way the property is constructed. Another factor to look at is whether the south facing roof is being obstructed.
If you can’t go south, then the next best positions are west and East facing. They produce 15% less energy than south. This is followed by north facing that generates 30% less electricity.
It’s a common misconception that solar panels can’t generate electricity in the shade. Although not quite an urban myth, you can, but not at maximum strength.
The issue is with the amount of shade and how many of the cells in the solar panel are being covered.
If you are concerned about roof shade, you can put light meters on your roof and monitor the shade throughout the day and season before deciding where to place your panels.
There are two things to take into consideration: the angle of the roof and also the angle of the panel.
This is an important factor to be aware as one angle doesn’t fit all seasons. This is because the height of the sun changes throughout the year.
Overall, a 60% angle is good in the fall and winter, but in the spring that can be reduced to 45% and in the summer, 20%.
Something to remember, when buying solar panels make sure they are adjustable.
An overall roof angle of 15-40 degrees is about right for your solar panels. If you have a flat roof or a very steep pitch, then the contractor can adjust the panels accordingly.
So you have a structurally sound roof, at the right angle, with plenty of sun, but will you able to generate enough electricity for your needs?
Roof size is the last bit of the jigsaw. On average, for every square foot of roof you can generate about 15 watts of energy. A Photovoltaic (PV) solar panels have a wattage from 150 watts to 370 watts per panel. These are what’s most commonly used by households.
Other factors that will affect this include where you live, the season and the available sunlight.
It’s worth noting that these are averages and vary widely. Someone in Texas is going to need less roof space than someone in Alaska.
To work out your requirements, this is where a calculator comes in handy. To make it easier to do the math, check out our solar panel calculator here.
So if you have a structurally sound roof, that’s of suitable size, with wonderful light and the right pitch, then you are well on your way to producing your own renewable energy.
If you would like to see how the leading roof solar panel contractors compare against each other click on the link.
To help deepen your understanding, so you can make dramatic savings on the cost of solar panels, we’ve put together the following articles that are guaranteed to support your decision making in investing in sustainable solar energy.