Solar and roofing – getting it right

Solar and roofing – getting it right

If you install solar panels on a building’s roof, you must consider if your roof’s integrity can withstand the load. A structural review of your roof is essential for cost, safety, and regulatory reasons before installation.

Getting a structurally sound sun-powered roof

After deciding to install a solar energy system, you may have many questions. Some of them will involve the solar modules and your roof. Installing solar equipment on a roof that isn’t sound is a significant health violation; it endangers human lives and risks damage to your equipment. Ignoring regulations and sound engineering practices will also cause you reputational damage and expose your business to compliance fines and penalties.

SolarAfrica is a leading solar energy company with decades of experience installing industrial and commercial solar modules. The team follows a process that is straightforward and transparent while still taking all of the complexities that come with a solar installation into account. We take it a step further than your average installer because we understand the risks of not getting the installation right. Here’s what you can expect from our technical review process when you install with us.

Pre-feasibility process for solar installation

SolarAfrica provides businesses with sustainable solutions that yield savings. If they can’t offer a financially viable solution, they would rather walk away from the deal instead of forcing a sale. This is why each potential customer goes through a tried and tested project process.

Qualifying lead

The first step is the qualifying lead or pre-feasibility process which will help determine how much electricity the customer needs, the size of the system, how much energy the system will produce, and a calculation of what the customer can expect in terms of savings. With that information, SolarAfrica will create a design and layout of the solar energy system that is aligned to the customer’s requirements.

Agreements are on a take-and-pay basis, meaning the customer only pays for the electricity they use. So the solar energy system must fit the customer's needs, nothing bigger or smaller; it must be the correct size.

Energy consumption rate

SolarAfrica will need to assess the energy consumption rate to determine the energy required for the business. To determine that, they can use an online meter with the year’s energy consumption ready to download. If the customer doesn’t have an online meter, SolarAfrica will install a meter reader and analyse the data to calculate an estimate. SolarAfrica will use the load estimates to refine the solar energy system sizing and yield; keep in mind that the solar yield will differ according to your location, climate, or sunlight exposure.

The above data is essential, but more is needed to evaluate the feasibility of a solar project. SolarAfrica will input the data into its proposal software, Unifii, to generate a preliminary proposal. When the customer signs the preliminary proposal, it will trigger the technical review process. The technical review process is essential because it will generate a bankable proposal and feasible design.

The technical review process for solar installation

Once the preliminary proposal is signed, the technical report starts. SolarAfrica will arrange a site visit by a in-house engineer. The engineer will provide unbiased, balanced insights and expert opinions on the installation’s feasibility. The engineer will:

  • Assess if the system design will work onsite.
  • Look into tie-in locations to connect to existing electrical infrastructure.
  • Note the cable line routes.
  • Inspect the intended layout for installation.
  • Consider the environmental impact, especially if the size reaches a level where environmental regulations kick in.
  • Check how the surroundings may affect the efficiency of the panels, and
  • Conduct a structural assessment of the roof

The roof structural assessment can take approximately two weeks. During the roof structural assessment, the engineers will check the following:

The current loading of the roof

The maximum allowed loading and whether the roof would be able to withstand the envisaged design and or layout.

The type of sheeting on the roof

Manufacturers have specific criteria regarding solar installations. The manufacturer will stipulate the mounting structure and procedures to use for installation. If the solar installation disregards the requirements from the manufacturer, it may void the sheeting’s warranty.

The tilt of the roof

The tilt will determine the roof’s ability to capture sunlight and its safety. By safety regulation, when a roof reaches a certain angle or tilt, the solar module must have additional safety equipment like anchor points and safety lines.

A qualified structural engineer comes with professional indemnity insurance, so you can claim from the insurance in the event of defect due to incorrect structural assessment.

The lifespan of a solar PPA with SolarAfrica can range from 7 – 25 years, so the roof sheeting needs to last for that long.

Mounting solar panels on your roof

Typically, a roof is built to keep rain and the elements out, not necessarily to carry heavy loads. Suppose you are building a megawatt system on a roof; at 555Wp per panel, that’ll come up to 1800 panels. At 26 kg per panel, you’ll be loading more than 46 tons on the roof.

If the structural engineer isn’t satisfied that the roof can handle the load, he will list the remedial work that needs to be done on the roof before installation.

SolaAfrica can repair your roof as part of the PPA.

If the roof needs work to handle the panel load in the initial assessment, such as replacing sheeting or putting a treatment on it, SolarAfrica will add the cost to the proposal. You will have the option of funding the repairs or letting SolarAfrica handle it. You can pay off the cost as part of the tariff over the term of the agreement. SolarAfrica will still need to ensure that with the additional costs and new tariff model, the project is still viable, i.e., save you money in the long run. It’s a principle.

Ideally, you want to fix everything before installation, so the roof is sound for 20 or more years. Fixing a roof five or ten years later will come with extra costs and complexities because you may have to take the solar modules (panels, frames, wires, and other equipment) down to fix it.

SolarAfrica can adjust the financial model according to what you have on the roof. If the roof space and loading is the limiting factor, SolarAfrica would look at other alternative locations to install solar panels to match the client requirements. Depending on the economics of the project, SolarAfrica may opt to reinforce the roof to allow for installation.

Solar installation regulations

Health and safety are crucial parts of any installation to avoid being criminally liable. Working on rooftops with awkward 1.7 m x 1 m panels weighing around 26 kg each means you should start with working at heights approval. All workers who work at heights must use fall protection on a project and attend an approved working-at-heights training program.

Installing solar panels on your roof

Adequate space is needed to install the solar modules; a rough guide is 10 m2 for every kW of power required. North-facing roofs are ideal in South Africa, with a tilt of approximately 25 to 30 degrees.

If you are changing the physical structure of a roof, you must go to the council, which applies to solar too. Starting with the roof at hand, is it a standard tile or chromadek roof? Most panels require only 100 mm clearance between the module and the roof. When installing on flat roofs, for example, there would be a change to the type of mounting structures used, as the panels would need to be inclined to make the most of the sunshine.

Interestingly, the City of Cape Town requests that all solar installations that connect to the grid have small-scale embedded energy (SSEG) certification, regardless of whether you intend to apply for SSEG rates or not. This means that even if you do not intend to “feedback” to the grid (i.e. apply for SSEG tariff rates), you still require this certification. Although not all municipalities have feed-in tariffs, all of them do require SSEG approval.

Don’t take chances with your roof

Your roof is an integral and crucial part of your building’s structure. When you decide to put a load on it, like solar panels, take the time to understand the implications. Ensure you partner with a solar installer that won’t risk your staff, building, equipment, and reputation.

Werner Fortuin

Head of Technical

Thank you to Werner for your insight and knowledge on this subject.

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