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Can You Install Solar Panels On A Flat Roof

Installing Flat Roof Solar

How to install solar panels on a flat roof DIY

If you are a UK home or business owner considering to install flat roof solar, get in touch! The green team here at Deege Solar will be more than happy to help you on your Solar journey. We are also able to discuss alternative types of solar panel mounting, just in case flat roof solar isnt suitable for your home! Call us on 01322 479369 or simply click enquire now to fill out our short form, to get connected to a Solar Energy expert.

Solar Design Options For Flat Roofs

Installing solar on flat roofs especially those with obstructions like hatches, skylights, and required FDNY fire paths requires a bit more creativity than other solar models. We pioneered two unique solar panel racking solutions for flat roofs, allowing us to provide customized solar panel systems for so-called challenging roofs that other companies wont touch.

Our most famous innovation for flat roof installations is our award-winning Brooklyn Solar Canopy. Canopies elevate solar panels above roof obstructions and required fire paths, while also creating space for roof decks, green roofs and other amenities. Its so popular that we now distribute our solar canopy to other installers all over the country through a separate company, Brooklyn Solar Canopy Co.

If a solar canopy is not your style, weve also mastered the art of maximizing solar with limited space through our tilt rack option. Tilt racks can be installed closer to the roof surface and allow the solar array to be split into sections, avoiding any obstructions. Tilt racks are great for landmarked homes, whose solar installations need to be invisible from street level.

Is It More Expensive To Install Solar Panels On A Flat Roof

It can be a little more expensive. The angled mounts that your installer uses adds a small amount to the total cost of the system. However, other factors mitigate that price difference.

For most solar systems, the cost of installation and labor make up around 10% of the total price tag.

But on a flat roof, those costs are reduced because working on a flat roof is inherently more accessible and safer than on a slanted one.

On an angled roof, workers need special safety equipment to do their work without falling off. Plus, roofing materials, such as shingles are likely to come loose during the process.

Neither of these is an issue on a flat roof. Installers can walk around freely, and the materials on flat roofs aren’t as likely to sustain damage during installation.

In the end, the price difference between installing on a flat roof using tilt-up mountings or installing on a pitched roof is usually only about $800 for a standard 7 kW residential solar power system.

Calculate the total cost of solar installation for your home!

Also Check: How To Extend A Roof Overhang

Benefits Of Flat Roof Solar Panels

Despite there being a few considerations when installing a solar array on your roof, there are several benefits of installing solar panels on a flat roof, including:

  • Solar panels provide cheap and green energy.
  • There are several types of panels available on flat roofs, including solar PV and solar thermal panels.
  • Feed-in tariffs are available if installed by an MCS certified installer, such as SolarTherm UK.
  • Flat roof panels are less visible from the ground than roof-mounted solar panels, so will cause less of a visual difference to your home or business premises.
  • Flat roof panels are easier to install which can save money on installation.
  • Flat roof panels are easier to maintain which can help ensure optimum efficiency of your panels.

Here Are Some Key Points To Keep In Mind

Can You Put Solar Panels on a Flat Roof?

Because these decisions should be made early in the process, having a design-build partner can afford you insights from a full spectrum of experts working on your project so that you can make the most informed choices from the projects inception. This ensures all stakeholders are on the same page and allows the owner to maximize their investment in solar technology. Lets explore the dynamics of this decision.

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How Solar Panels Are Mounted On Flat Roofs

Flat roofs require different installation techniques than sloped roofs. One method is known as direct attachment or fixed racking, which requires holes to be drilled in your roof. Unfortunately, direct attachment does increase your chances of leakage during storms, but it allows for a wider range of tilt angles so you can get the most solar energy possible. Installation teams usually work with a roofer when doing direct attachment, and specialized tape or caulking can be used for leak protection.

If you dont want to risk leakage, ballasted systems are a great non-penetrating option. This simple technique uses concrete blocks to weigh down the racking system, and its proven to still provide the support and durability you need. This technique isnt ideal for older, more worn down roofs, since the added weight can lead to sagging and structural problems. For more modern roofs designed with a slight tilt towards the drainage system, your team might decide to use a hybrid system which combines these two methods for optimal durability and longevity of your roof.

Also Check: Can You Make Money On Solar Panels

Do You Need Planning Permission For Flat Roof Solar Panels

You usually need planning permission to install flat roof solar panels.

Solar panels on pitched or tilted house roofs rarely require planning permission because they fall under the permitted development’ category but that’s not the case with flat roof solar panels.

Since they aren’t classified as permitted developments, planning permission is more likely to be required.

Its therefore a good idea to check withThe Planning Portal the national planning application service for England and Wales.

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Use Racks To Install Solar Panels On Flat Roofs

It may seem like the best way to install flat solar panels on a flat roof is to just simply attach them to that roof is ok but its not. Factors such as which way the solar panels will catch the most sun during the day have to be considered. Thats also the reason why its best to install solar panels on specially built racks so they can be slightly angled to catch the highest amount of sun each day. This will help maximize that flat roof solar setups efficiency. You may also want to consider attaching the racks you will place your solar panels on with ballast instead of drilling holes into your roof. This can help prevent damage to your roof that ends up causing leaks.

Frameless Panels Are Better At Low Angles

Flat Roof Solar Panel Install – Aldershot #solarpower

Most solar panels have an aluminium frame. This strengthens them, protects the edges from damage, and serves as an attachment point. But there are frameless ones and these can be useful if panels have to be installed with less than 10 degrees tilt. Without a raised frame at their edge it is easier for water to flow off them. If they are laid completely flat, some water will still collect on their surface, but not nearly as much.

Manufacturers are looking at frameless panels in an effort to reduce costs, but at the moment most frameless solar panels are double glass and carry a considerable premium over conventional modules1. Although when you consider these additional advantages of frameless solar panels, you may be persuaded to pay the premium:

  • typically 0.5% warranted degradation per year compared to 0.7% for framed panels
  • typically 30 year performance warranty instead of 25 years
  • less risk of long-term performance issues by not having a plastic back sheet

Update 16th October 2019: Frameless panels can require yearly maintenance by a professional and this expense should be considered when determining if they are cost-effective. For this reason we have changed our advice. If you are going to install panels at a tilt under 10 degrees, we recommend panels with drainage slots.

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Common Problems With Solar Panels On Roofs

Solar installation on a flat roof is significantly different from installing other HVAC systems in the house. As a result, solar panels can face several problems. Here are some problems you might face if you install solar panels on the rooftop:

  • Electrical wiring issues
  • Electrical wiring issues are quite common for all households. Under this category, your solar system may not face the issue however, another wiring in the house might. These include loose connections, corrosion, and so forth. Thankfully, it can be fixed by calling an electrician.

  • Internal corrosion
  • Internal corrosion of your solar panel can occur if water seeps into the solar panel. Most solar panels are designed to be air and water-tight. However, if the panel is damaged, it cannot be fixed and should be replaced.

    Poor design and a solar installation on flat rooftops can cause problems to the water lines and electrical wires on the roof. This can cause leakage from the pipe, which can damage the roof. A solar expert should be called to assess the situation.

    Installation Costs Are Competitive And Can Be Less Expensive

    Many people assume that installing solar panels on flat roofs is more expensive, but that is not always the case. The costs between this system and the traditional pitched one is similar. Both types of systems require labor and installation fees to account for about ten percent of the total installation expenses.

    In general, solar panel installation on a flat roof can be less expensive than adding panels to a pitched roof. This is because labor can be cheaper. Unlike the logistics involved in installing solar panels by climbing around on a steep roof, workers can move freely on a flat roof without special equipment.

    As an added benefit, multiple holes in your flat roof dont have to be drilled. You just have to use a weighted mounting system, also known as a ballast system, to hold the solar panels securely.

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    Whats So Different About A Flatroof

    A roof is a roof, right? Not in this case, apparently. There wereloads of reference guides for installing solar panels on traditional roofs. Anymention of flat roofs and the articles got very tight-lipped on the topic,instead, making what seemed like strange warnings.

    Writers would sing the praises about the ease ofstandard install and then basically issue words of warning for usflat-roofers. Statements like: Thesepanels can also installed on a flat roof, however, self-installation is notadvised.

    There were even blatant warnings suggestingthat an inspector be called in first to do an inspection of the roof in orderto insure safe installation. More than a few times, I was warned aboutpotentially hazardous leaks developing in the roof. It was time to reallydetermine fact from fiction and figure out how I was going to accomplish mytask.

    Comparison Between Inclined Vs Flat Solar Panels Simulation Results

    Solar Panels Flat Roof

    We did 2 simulations for an 11.2kWp solar power system. One with 5 degrees inclination and the other is with flat solar panels or with a 0-degree tilt angle.

    If you want to learn how to do solar power system simulation, you may want to check this article. Here are the results:

    As seen in the results, the system will produce 586kWh more each year just by having 5 degrees tilt than having it flat. This is not even considering the losses due to dust accumulation on your panels if you install the solar panels at a zero-degree tilt.

    At 10 degrees tilt angle, the 11.2kWp system will produce 14,520kWh to the grid in one year.

    So, to avoid these disadvantages, you should install your solar panels with at least 5 degrees tilt angle. You can do this by choosing the correct mounting supports for your modules. This way, your flat roof solar power system will generate more kWh.

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    Tilt Racks Are Cooling

    Installing solar panels helps keep buildings cool and reduces air conditioning costs. Panels in tilt racks can be slightly more effective at this because there is more room for air to circulate behind panels than ones mounted flush against a sloped roof. Because they are just a little bit cooler on average they generate slightly more electricity, but its not really enough to be noticeable.

    I will mention one more trick for reducing air conditioning costs using solar panels. This picture from Google Maps shows an Adelaide building with a rooftop solar power system:

    At the top of the picture you can panels arranged in tilt racks, but at the bottom of the picture you can see half a dozen or so small arrays consisting of three solar panels each that are either at much less of an angle or mounted flat, but you can see from their shadows they are raised off the roof. While it cant be seen in this picture, those panels actually shade air conditioner units and help keep them cool so they use slightly less electricity. While this arrangement is unlikely to be practical for most installations, its still an interesting use of solar panels on a flat roof.

    You Can Still Get Optimal Energy Performance For Flat Roof Solar Panels

    Regardless of the type of installation, flat roof solar panels can still get optimal energy performance. This can be done in different ways.

    One way is by adjusting the solar arrays to optimum tilt angles, and to the optimum direction where the modules will face on the roof. This is an important thing to be included during the design stage. It is recommended that you prepare the drawing and the layout of the solar panels.

    Additionally, you can achieve optimal performance from your system by minimizing the shading effects on your solar power system. It can be achieved by adjusting the inter-row distances of solar arrays. This is very effective especially if your roof space is massive. If your flat roof has high parapet walls, choosing the right racking system, which will elevate the solar modules, is the best thing to do. Knowing and applying these things will help minimize the shading effects on your flat roof solar arrays.

    When installation day begins, start with ensuring the solar racking system conforms to your design and drawing. Then, complete the installation knowing that you have considered all the factors mentioned above.

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    Connect Floor Rails Withthe Support Rails

    The solar panels will be mounted on theserails later. Its imperative that all of the rails are laid out on the roofprior to any further steps are taken. Once these are installed, its notsomething you want to take apart and reassemble over and over. All that will dois cause the mounting kit parts to lose integrity.

    What Financial Savings Might Solar Energy Offer

    How to install solar panels yourself on your roof. (It’s easier than you think)

    The average three-bedroom house will save £534 per year with a 3.5 kWp solar PV system.

    Our research into whether solar panels are worth it also shows that if you installed solar panels today, youd break even in 10.2 years, and make an overall profit of £7,932 after 25 years.

    And with 65% of people telling our latest Go green because, according to the National Home Energy Survey, theyd purchase a home with solar panels.

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    Dont Lay Regular Solar Panels Flat

    The easiest way to install solar panels on a flat roof may appear to be to lay them flat out like a lizard drinking, but this can result in your lizard getting very dirty indeed. Usually rain alone is enough to keep solar panels clean on a typical sloped roof because rainwater will flow off them, carrying away dirt. But when panels lie flat, water will pool on top of them and stay there after it stops raining. This water can collect dust and windborne debris, such as leaves, which will stay behind when the water evaporates. This means they dont self clean well and can become very grubby. Google found the output of their flat panels was cut in half after 15 months without a clean, while rain alone was enough to keep their tilted solar panels pretty pristine.

    To keep panels clean on a flat roof it is recommended they be installed in racks that tilt them at an angle of at least 10 degrees so rain can effectively wash them clean. Also, while good quality solar panels should be resistant to the effects of water, its still not a good idea to let water pool on them so they soak longer than is necessary.

    Installing Solar Panels Onto A Flat Roof

    Your roof is flat, so you can just put the panels on top and Voila! job done, right? Well, no, unfortunately its not quite that simple!

    Theres no doubt that using solar power is a great choice for many reasons, but its also important to consider the wider impact of fitting solar panels onto your flat roof. You must ensure that your solar panels dont compromise the roofs primary function, which is to remain watertight and insulated, protecting the interior of the property from external elements.

    Rather than simply putting solar panels on top of your flat roof, your solar panel system will need to be designed and fitted to your specific requirements. Great care must be taken over the layout of the panels on a flat roof to ensure they work to their maximum potential.

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    How To Install Solar Panels On Flat Roofs

    To install solar panels on a flat roof, you can start by arranging the concrete blocks that will serve as the foundation where the mountings structures will be fixed. The next thing to do is to fix the aluminum or steel mounting structures on the concrete blocks. After installing the mounting structures, you will then have to fix the solar panels on the metal structures using the rails, mid clamps and end clamps.

    Once the solar panels are fixed on the mounting structures, you will then need to wire them according to the design of the solar PV strings. This is done by connecting the male MC4 connector of one solar panel to the female MC4 connector of the next module. Each string will then be connected to the inverter.


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