What is the Best Roof for Solar Panels?

What is the Best Roof for Solar Panels?

Installing solar panels on your home or business premises is a great way to generate your own electricity, saving you money and helping the environment. While you may be tempted to think that fitting solar panels is a complex and difficult process, if you work with the right people it’s really fairly straightforward. In most cases, solar panels are fitted to the roof of a property, so if you have a roof over your head, chances are you can fit solar panels to it.

Tilted Roof

A tilted roof is ideal, as the solar panels work best when fitted at an angle. A tilt of between 30-50 degrees is optimum for maximum year-round performance, but the panels will still work outside of this. If you have a flat roof, you can choose to mount the panels on a tilted frame in order to optimize their efficiency.

Anywhere between 20 and 40 degrees ensures good power generation across the course of the day. In some places a 35 to 50 degree roof tilt is optimal for year-round energy production. In Seattle, for example, solar panels produce the maximum power annually when mounted at a tilt of roughly 30 degrees.

Flat roofs also work relatively well for solar systems because the PV panels can be mounted flat on the roof facing the sky, or mounted on frames tilted toward the south at the optimal angle would be the best. But a minimum tilt of 10° is recommended to ensure self cleaning by rainfall.
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Roof shape

Solar panels are generally rectangular in shape and measure somewhere in the region of 1m x 1.5m each. They can be mounted horizontally or vertically (“portrait” or “landscape” if you like) and the modular nature of a solar panel system means it is relatively easy to design an array to fit any shape or size of roof. As they are flat and fit flush with your roof surface, an added bonus is that they keep the look of your property intact.

Orientation


The panels will be most effective facing due south, but will work perfectly well facing to the south east or south west. Installing solar panels facing north is not recommended as they will not get enough direct sunlight to operate efficiently.

Light and shade

When assessing the suitability of your roof for solar panels, you need to take into account any surrounding features, such as trees or chimney stacks, that might cast a shadow on the panels. It’s generally not advisable to install panels in direct shade as they won’t work as effectively.

There are many factors that can reduce the production of a solar array, shade is often the biggest. Solar PV panels should ideally be in full sun from at least 9am to 3pm.

They should not be placed in shaded areas and be kept free from dust and dirt. Shading or dirt on just one of the cells in a solar panel results in a loss of power from many cells, not just the one that is shaded.

A small amount of shade may, at first, seem like a small problem to your roof-top solar pv installation. But even part shading of one crystalline panel will significantly reduce the output from the whole array of panels, as it changes the flow of electricity through the panel. The cells within a PV module are wired in series, this enables shade on a cell to block the path of current flow. Thus, a little shade can cause a disproportionate reduction in PV energy production.

Avoid shading as much as possible, even minimal solar pv system shading can significantly impact your solar power production. You will want to consider potential shading from: trees, buildings, power lines, telephone poles, roof ventilators or antennas, and obstructions like chimneys and vent pipes, roof gables, or other features of your home and the surrounding landscape

Space required on your roof

The amount of space needed by a solar PV system is based on your present electricity needs and the physical size of the system you purchase. A small starter solar system require as little as 50 square feet and go up to as much as 1,000 square feet. Each manufacturer has its own set standard for solar panel type, size and efficiency.
About 12 m2 of roof space is required for a 1.5 kW solar panel system using silicone crystalline panels.
An equivalent system in amorphous thin film solar panels would require almost 20 m2.

More efficient solar panels use less roof area

If your location limits the physical size of your system, you may want to install a system that uses more efficient PV panels. Greater efficiency panels are more efficient per square foot and need less roof area to convert sunlight into a given amount of electric power. Depending on several factors, the cost of a system using higher-efficiency solar modules can be comparable to the same system using low-efficiency modules.

Getting permission


In the vast majority of cases, no planning permission is required to fit solar panels. With the government keen to encourage the use of renewable energy sources, you should have no problems as long as your panels don’t protrude by more than 200mm (which most won’t). It is always wise to double check with your local authority though, especially if you occupy a listed building or live in a conservation area.

Finding the right people for the job

A great way to get started is to fill in our quick and simple form. You will then receive quotes from up to 3 reputable local suppliers of solar panels. All of our suppliers should be accredited and have a reputation for excellent service. They will be able to help you with any technical questions but you may also find the guide below useful when determining the suitability of your premises for solar panels.

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