Nottingham taking the lead in solar carports

DSC08946Solar carports are the next hot topic in the solar industry, set to transform grey windy carparks into “energy hubs” generating cheap, green electricity for buildings and electric vehicles. Nottingham City Council is leading the way and has built the UK’s largest solar photovoltaic (PV).

Canopies covering 40 car parking spaces deliver 65kWp (kiloWatt peak) – enough to power 20 homes. By reduced costs of purchasing energy, Nottingham City Council are hoping to generate over £8,000 revenue per year from the project. All this is achieved without Feed-in Tariffs, which is especially relevant in light of the proposed DECC cuts on renewable subsidies.
This is just the beginning for Nottingham, which has plans for two more 1MWp carports, powering 479 homes a year while also generating around £216,000 annually for the council and saving 600 tonnes of carbon annually.

Solar carports deliver something missing in the solar industry since the government cut the Feed-in Tariffs on solar farms – scale. Nottingham City Council have installed only 250kWp of commercial rooftop PV to date, but solar carport projects are set to increase installed capacity by over 400%.

The Business Case

At the core of any sound business case is a revenue stream that delivers a stable income over a planned asset lifetime. Typical internal rates of return (IRR) on solar carport projects are between 9-12% with pay-backs from 7 years. Nottingham calculated the income from Feed-in Tariffs, Export tariffs and the reduction in national grid energy costs make solar carports more than viable.

Additional benefits brought by solar carports add to the project value. Electric Vehicle (EV) charging can be installed into the canopy structure and achieving substantial project cost savings by subsidising the laying of electrical cable and other infrastructure.
Another factor high on council scorecards are carbon emissions. With most councils targeting a 30% reduction in 2005 levels of CO2, large scale renewable projects are seen as vital to deliver such ambitious goals.

For the private sector, where payback periods of less than 5 years are often required, other revenue streams can be considered. Recent data from Germany shows that solar carports dramatically increase footfall because of the convenience of parking under a canopy. Increased land values, premium rental and improved customer experience are quantifiable benefits that can be financially modelled.

Sources of Funding

Local authorities have access to the government financing of infrastructure projects. Public Works Loan Board exists in order to allow local authorities to access the UK’s low cost of borrowing and offer interest only payments on the principle borrowed. Currently repayment rates at 3%, meaning that even the lowest of solar carport IRR of 9% can create net positive cash positions from day one.

The RE:FiT framework is an initiate to reduce carbon emission for the entire public sector. Over 180 public sector bodies use the framework to roll out energy reduction measures with the help of private sector expertise and funding. Institutional investors, the Green Bank and EU funding are all available to finance the capital cost of solar carports.

For the private sector solar carports can be a viable solution. Large users of power or long term lease holders can form business cases for solar carports. The private sector should also consider that the solar carport is an asset and can be sold. Recently, the largest solar farm in the UK, a 33MWp plant in Leicestershire, was sold by Hazel Capital Solar for £43.7 million to institutional investor Foresight Solar Fund.



For the public sector OJEU compliant tendering process is required for projects exceeding the current threshold of £111,000. Nottingham chose a trial site beneath the threshold in order to foster innovation and new products in their supply chain.

If a council operates under a RE:FIT framework then the solar carport project should be identified as an Energy Saving Measure (EMS) and brought to the attention of your RE:FiT Programme Delivery Unit (PDU). Payback of the investment is guaranteed and the risk is transferred to a private sector Energy Services Company (ESCo). Fortunately, the RE:FiT framework is OJEU compliant and avoids the need for a solar carport provider to be an existing member of your organisation’s procurement framework. “The money for a RE:FIT Project is in your budget – it is currently being spent on wasted energy” urges Robert McKinnon Engagement Lead at Local Partnerships, a HM Treasury and the LGA owned organisation charged with supporting public sector delivery.

A new route to procuring innovative solutions in the PV sector is Public Power Solutions’ Dynamic Purchasing System. Currently used by the Crown Estates to procure a pipeline of over 2.5MWp of carport systems. John Nangle of Crown Commercial Services describes the service as “an excellent way to procure rapidly for new-to-market PV products”

Large private sector organisations often have delivery partners for facilities management, construction and more specifically commercial rooftop PV systems. Although there are a dearth of firms that offer commercial rooftop systems, these companies experience does not transfer to the planning permissions, civil works and complex project management skills required in solar carport installation. Consider where possible turnkey providers of solar carports. But the reality is that often large multisite corporations have exclusive hard FM contractors who will have to subcontract much of the solar carport design and delivery to specialist manufacturers.

Solar Carport Design and Cost

Experienced solar carport developers can add substantial value to your system and your business case. However many terms and metrics are obscure to non-PV professionals so look for a bottom line interpretation of design specifications. For example, optimising the PV panel arrangement and orientation within an existing carpark layout can at 1% to the project IRR.

Those with a portfolio of sites should expect advice on site selection. Large energy consumers who use all the energy produced by solar carports can add 4.5% to their planned IRR. Feed-in Tariffs descrease with system size in steps so choosing the correct system size to maximise tariff revenue can add up to 3% to IRR. Despite the scrapping of Feed-in Tariffs, large energy consumers can develop robust businesses cases with solar carports.

Systems should be able to offer 2kW per car parking bay while project cost is reaching parity with commercial rooftop PV systems. Commercial rooftop PV typically cost £800-£1200/kWp whereas solar carports cost £900-£1400/kWp. The size of your solar carport system, the chosen design and the site will all determine the final project cost.


About the author

Christopher Jackson is the designer of the UK’s largest solar carport. He leads product development for Flexisolar Ltd.