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Commercial solar installation process. On this page:

Commercial solar installation process. On this page:

    Installing solar panels on your commercial building roof? Here’s everything you need to know

    Concerns over the security of supply, rising costs, and the need to decarbonise environments have quickly and permanently transformed our energy landscape.

    In the last year it has become increasingly clear that the way power is generated, purchased, and distributed today is not sustainable. Global supply chains have created a system that is simply too unstable to provide security in terms of supply and cost. And our reliance on fossil fuels is increasingly considered too damaging to an environment that’s already at breaking point.

    Simply put, now is the time to look at the alternatives. Because if we can be sure of anything, it’s that the disruptions of the last year will probably happen again.

    This is a great opportunity for commercial building owners to take advantage of cheap, clean, and sustainable energy sources. Solar PV is one of the most reliable investments in a turbulent market.

    You probably already know the many benefits of having solar panels on commercial rooftops – from energy security and lower costs to reduced risk and added value for your portfolio. You may even have decided that this is the way forward for you. But you might be less clear on what to do next and what to look for in a renewable energy partner.

    What to consider for your commercial rooftop solar installations

    Your specialist partner can help with the process of gaining commercial solar panel planning permission and accessing the right commercial solar panel grants. They can also design the configuration of your array, install it, and carry out the necessary maintenance and repairs.

    Since 2010, Mitie has developed, designed and installed, some of the largest commercial solar roof projects in the UK. And we’ve worked in some challenging environments. Our specialists know this world inside out, which is why we’re perfectly placed to guide you in your search for a new clean energy provider.

    Commercial solar installations are a lot for an organisation to take on. The process can be time-consuming and needs specialist knowledge so it’s always best to work with expert partners who know their way around.

    Design and installation of your solar PV

    The design and installation of solar is more than a two-step process. You must begin with a thorough understanding of your consumption, a clear idea of your goals, and a knowledge of the opportunity solar presents. You then need someone who can help you design the best system to meet these needs in your specific environment. And, trust us, this varies hugely from job to job.

    You must consider planning restrictions, cabling solutions, safety measures and so much more. As a result, every solar installation is different so you need to make sure your partner has a breadth of experience working in different environments.

    Remote monitoring for maximum performance

    Once everything is in place, you need assurance that your solar panels are performing at their best to provide the maximum ROI. A good partner will use digital technology to remotely monitor your energy generation and identify any panels that are not performing at full capacity.

    Maintenance and repair

    Of course, there’s no point monitoring if you’re not going to use the data to take any necessary action. Commercial solar panel maintenance and repair is essential in reducing preventable downtime, ensuring your energy needs are met, and maximising ROI.

    In most instances, this will include:

    • Professional cleaning to remove dirt and debris from your panels and optimise their performance.
    • Maintenance on inverters to optimise generation.
    • Regular checks to mountings, electronics, fixtures and fittings to keep panels secure, safe and operational.

    End-to-end delivery for consistency

    At Mitie, we know from our own experience that a successful commercial solar project benefits hugely from end-to-end design and delivery services. A specialist partner, with expertise at each stage, from initial planning to installation and maintenance, can simplify the process.

    After all, who better to monitor, service, and repair your solar infrastructure than the people who designed it, installed it, and know its every intricacy?

    How Mitie helps organisations embrace solar power

    Our work helping organisations to decarbonise and embrace sustainable energy has seen us install solar arrays for some of the biggest brands in Britain. On behalf of our customers, we’ve been on the rooftops of supermarkets, warehouses, council buildings, carparks and transport terminals, and everything in between.

    Powering our ports

    Our recent work includes two projects with Associated British Ports (ABP), the UK’s leading port operator. ABP contributes billions to the British economy through a unique network of 21 ports, nationwide. The operator has a policy to deliver renewable technology to reduce energy consumption and CO2 emissions.

    In 2018, we delivered a 1MWp solar project across six operational buildings at the Port of Southampton, including the 500kWp installation on the UK’s largest terminal. Our specialists began with extensive harmonic studies to satisfy the requirements of the District Network Operator.

    Today, we provide full maintenance and annual servicing of the solar PV systems, including remote live monitoring, for the port. In total, the system has outperformed predicted yields by 10%.

    Following the success of this project, we’ve also installed a 6.5MWp solar system, made up of 21,000 solar panels, across the rooftops of terminals at the Port of Hull. The system now generates enough electricity, at its peak, for the port to run on clean energy alone.

    Overcoming the challenges

    Every commercial solar project has its own specific challenges. The Port of Hull project happened at the particularly challenging time of the Covid-19 outbreak. Also, we had to work with a building over 350 metres long, which required permanent pathways to be built to prevent surface damage from the installation. It also needed a specialist approach to cabling to prevent overheating.

    The positive thing about overcoming complexity, however, is that it can yield generous rewards. After two years of planning, the £6.8 million investment became the UK’s largest rooftop solar installation. And, in 2020, it received the accolade of the Solar and Storage Awards: Commercial Project of the Year.

    As with Southampton, we operate and maintain the systems across the port, providing live monitoring, full reactive maintenance and annual scheduled servicing.

    If you’re ready for solar, get in touch

    If your organisation is about to make the leap to solar, and you want to know the difference a clean energy partner can make, get in touch.

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    Are you considering solar power for a commercial or industrial building? Get a professional design.

    High-quality solar panels can last for more than 25 years, and many manufacturers now offer a matching 25-year product warranty. To take advantage of this durability, solar panels should be used on commercial roofs that will have the same service life. A roof replacement can be an expensive project, and costs are even higher when you must remove and reinstall a solar array. Also keep in mind that solar panels and other components may be damaged during the process, and you will most likely lose the warranty.

    Considering this, the best time to install solar panels on a commercial building is right after construction when the roof is new, or along with a planned roof replacement. The worst-case scenario is being forced to replace a roof with solar panels installed, especially if they are relatively new. The additional cost of removing and reinstalling solar panels will consume a major portion of their lifetime savings: the ownership cost becomes much higher, and your ROI is drastically reduced.

    ) The Solar Panel Layout Should Consider Maintenance Needs

    Commercial roofs are often used for HVAC equipment like cooling towers and air-cooled chillers, and they also have drainage systems and vents. If you’re considering a solar PV array, its layout should not interfere with the operation and maintenance of these systems. The maintenance needs of the roof itself must also be taken into account.

    To optimize your roof layout, an easy solution is working with the same engineering firm for the commercial solar design and MEP design. This will ensure that all equipment has enough clearance for maintenance, and you will also meet the rooftop access requirements of local fire codes.

    Ideally, the commercial solar array should be split into groups of panels, with enough spacing for maintenance. With this layout, you can easily access a specific panel or roof location if necessary. On the other hand, when a commercial solar array lacks spacing between rows of panels, reaching the center is very difficult.

    ) Consider a Reflective Roof Surface with Bifacial Solar Panels

    As the operating temperature of solar panels increases, their productivity drops. This loss is typically 0.5% per °C or less when using high-quality PV modules, but it adds up as the temperature rises. For example, a 24°C rise in the operating temperature of solar panels will result in a productivity drop of up to 12%.

    • Solar panels tend to have a higher operating temperature on opaque roofs, since they absorb more sunlight.
    • By using a reflective roof surface, you can reduce the temperature of solar panels and improve their electricity output.

    You can achieve even better results with bifacial solar panels, which have their photovoltaic cells exposed from above and below. This means they generate power with sunlight that reaches them directly, just like conventional solar panels, but also with sunlight reflected by the roof.

    How long does a solar panel installation take?

    One of the first questions homeowners have when they’re thinking about installing home solar panels is “how long will the installation take?”. Believe it or not, the actual installation can take as little as six hours. But, going solar consists of a lot more than just getting contractors up on your roof. There are a few additional factors you need to keep in mind when trying to plan out how and when to complete your installation.

    We’ll walk you through the solar installation process and determine how long it may take for your home.

    See how much you can save with solar panels

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    Solar installation timeline at a glance

    • The total solar installation process will take somewhere between two and six months to complete.
    • Typically, contractors install a residential solar system in as little as 6 hours.
    • The longest part of the installation process is waiting for permit approval, which has the potential to take almost two months to complete.
    • Once the system is installed, you still need to wait for one to six weeks for your city and utility to inspect and approve the installation.
    • Waiting for the installation to be complete is worth the investment, as the system will provide you with thousands of dollars in electrical bill savings over 25 years.

    Solar panel installation process timeline

    Installation is just one piece of the puzzle when it comes to switching to solar. Eight key steps make the entire process last anywhere from two to six months on average.

    Choosing a solar installer

    Time: 1 day to 2 weeks

    Choosing a solar installer is the first and most important step of your entire solar journey. What company you pick determines not only the price of your installation but the quality and timeline as well!

    You want to make sure you’re picking a reliable company that’s been in business for at least 5 years, have a NABCEP certified installer, and has positive customer reviews. This step can take you just a few hours, but it’s important to take the time to not only find a few installers you like, but also get and compare quotes from them. You definitely don’t want to cut corners when it comes to choosing the right company.

    Getting at least three quotes will increase your chances of getting the highest quality installation at the best price point. The easiest way to find trustworthy solar companies in your area is by using our state-of-the-art solar calculator, which lets you see your potential solar savings and can help you start collecting quotes.

    Find trusted solar installers in your area

    Site assessment

    Time: 1 week

    After you choose your solar installer, they’ll need to perform a site assessment to make sure your roof is suitable for a solar installation. Someone from the installation company will come out to your house and take a look around to check out the condition, shading, size, and direction of your roof. They’ll also make sure your roof can handle the weight of solar panels, and take a look at your electrical panel to see if it would need any upgrades.

    The site assessment will take less than a day, just a few hours at most, but we give this a timeframe of about one week to take scheduling into account.

    System design

    Time: 2 to 3 weeks

    Once it’s determined that your roof is ready for solar, an engineer will get started on designing your solar system. Your electricity usage, roof characteristics, local building code requirements, and utility requirements are all taken into account when designing the system.

    The design process can take anywhere from two to three weeks on average, but it may take longer if your roof is more complex. Still, the planning stage for complicated systems probably won’t take much more than four weeks to complete.

    commercial, solar, installation, process

    Applying for building and solar permits

    Time: 2 to 7 weeks

    Adding solar panels is a construction project, so you need to have all of the proper permits before installation begins. Sadly, the permitting process is probably going to be the longest part of going solar. The exact permits needed vary from town to town. Some have very solar-specific permits while others have various building and electrical permits that need to be obtained.

    Depending on the types of permits needed and the permitting processes in place in your municipality, it could take just two weeks to get approval – or almost two months. Let’s face it, having to wait that long for permits is annoying. But, the good news is your solar installer is the one who handles all the paperwork – you don’t have to worry about it.

    Ordering equipment and scheduling installation

    Time: 1 to 4 weeks

    When your permits are approved, your company can start making moves to actually install your system. Some installers have the equipment on hand so they can get started on your project ASAP. You won’t have to wait for equipment to ship, but you might have to wait for them to have time in their schedule for your installation. That’s why we give this stage about a week minimum.

    If your installer doesn’t have supplies at the ready, it could take a few weeks for everything they need to get delivered, especially with the ongoing solar industry supply chain issues.

    Attention battery buyers: You may have to wait even longer if you are pairing your solar panels with solar battery storage. Batteries are in high demand, and it can be tricky to get your hands on one in a timely manner. Some installers may have them in stock, but don’t be surprised if the battery adds a significant amount to your wait time.


    Time: 6 hours to 3 days

    As we said earlier, the actual installation of your solar panels is going to be the shortest part of the process. For most residential solar installations, it’ll take just about 6 hours to complete!

    So, how long does it really take to go solar?

    When you consider everything you have to do in order to get solar on your roof, you can typically expect it to take as little as two months to as long as six months. Keep in mind that this timeline is an estimate, and it can vary greatly depending on your specific circumstances. Your solar installer will give you the rundown on what the timeline usually is in your area.

    We get it, six months is a while. But, as the saying goes, good things come to those who wait. Even though it takes a few months to get the installation completed, in many cases it will take only 9 years (or even less!) for the solar panels to pay for themselves. Then, you’ll get over 15 years of completely free electricity. Plus, it’s good for the planet. who doesn’t love that?

    If you’re still on the fence about whether or not you want to invest your time and money into a solar installation, you can use our free solar panel calculator to get insight on the number of solar panels you need, what incentives are available, how much you can save, and how long the payback period will be.

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    What to expect from application to commissioning

    Once your application has been received, it typically takes seven to 10 business days for review and approval.

    Here’s what to expect after your application is approved:

    SRP design review

    Once your application is approved, SRP will assign a design consultant to review the drawings and visit the site pre-construction to make sure the proposed installation complies with SRP’s interconnection guidelines.

    Installation and initial inspection

    Once you get the approval to install, you must obtain all applicable building permits as required by the authority having jurisdiction (AHJ). See the full steps below.

    Final SRP inspection

    Once the city clearance or the Certificate-In-Lieu of Clearance (CILC) has been received, SRP will perform a final inspection of the system and will leave a notification at the site indicating whether the system passed or failed.

    Sign the interconnection agreement

    Once you pass your SRP system inspection, you must submit a signed Distribution Interconnection Agreement to SRP prior to commissioning. The agreement is available in our PowerClerk online application. A CILC is provided in lieu of city clearance for projects not requiring building permits or inspections by the authority having jurisdiction.


    SRP will schedule the commissioning and notify the customer and contractor of the appointment through email.

    At the time of commissioning, SRP will set the metering for the solar power system and perform an interconnection test of the system. The customer or contractor must be present to operate the equipment. The customer’s equipment may not operate at any time prior to the successful completion of the interconnection test.

    Upon successful completion of the commissioning, the system will be permitted to operate.

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