Last week analysis conducted within property consultancy Carter Jonas’ 2015 Energy Index revealed a 50kW rooftop installation to be the most attractive renewable energy investment in the UK, beating stern competition from wind, biomass and policy-afflicted ground-mount installations.

However the rooftop PV market continues to flounder in comparison to what many within the industry think it truly capable of. Energy and climate change secretary Amber Rudd has sought to trigger a “solar revolution” on rooftops, but so far a lack of governmental stimulation has meant solar companies themselves have had to push the market along.

Andrew Watkin, head of the Energy and Marine team at Carter Jonas, believes that until now ground-mounted developments have simply been more appealing for developers but that by pushing the financial incentives of a rooftop installation, on top of what businesses will have to do with regards to the EPC ratings of their premises, solar rooftops can flourish.

Why do you think the solar rooftop market hasn’t quite met expectations?

Solar rooftops have taken off to a certain extent, but I would say that one of the reasons it hasn't been deployed at the same level as ground-mount is because of the scale. Rooftop solar is happening but in terms of being able to deploy multi-megawatts, it's so much easier on the ground than it would be on a myriad of roofs in the middle of a city which all have separate property rights.

If you're taking a city as an example or a street which has got south-facing roof elevations, each of those properties is likely to be owned by separate parties. So to actually get everyone into solar, they're all going to have to have the backing to invest in the technology and you also need everyone to embrace it along the street, otherwise you're just putting on 4kW here and maybe the house next door.

Is that lack of scale putting off some companies from getting involved?

If you compare that to deploying a solar park, then probably with that kind of project you're dealing with one landowner rather than a myriad of property owners down a street in the town. For a multi-megawatt park you've got scale, so you can get economies of scale into the EPC price, hopefully you can get grid connection, although that's becoming scarcer, and if you've got a willing landowner then suddenly you're deploying megawatts instead of just kilowatts.

Of course there are opportunities with commercial premises and businesses that have high energy use, and I think we'll see the game change slightly. More importance will be given to EPC ratings and also energy saving opportunity schemes, which applies to businesses that fit certain criteria.

Why else do you think developers have simply preferred fitting ground-mounted projects?

A large part is the development premiums available for site rights, including grid connection, planning consent and a landowner lease – and that's why a lot of developers have been keen to push through large solar parks. If the developer turns around and wants to sell those on to a party that can operate it rather doing it themselves, there have been some very significant development premiums available. I think that's been a lot easier to achieve in comparison to developing out rooftops.

And with ground-mounted development now falling foul of government cuts, could that now shift to rooftops?

The large-scale commercial premises are quite straightforward and there all sorts of businesses and warehouses that could install PV. Some are however more switched onto it than others and I suspect with EPC ratings and the energy savings opportunity scheme, people and businesses are going to have to wake up to the fact that they might have to do something about their energy usage and consumption.

What can solar do to simulate the rooftop market?

Keep dropping the price of the panels and inverters to be perfectly honest with you, and ensure it's an investment-grade product. If we end up in a tariff-free world – and I think the industry would say we're not at that stage yet – we'd have to work a financial model out to see what level power prices were when you're purchasing power from the likes of E.ON and SSE against what it's going to cost you to install a PV array so you can get your electricity and make it attractive enough for you to install that technology and not take any Feed-in Tariff. We're not at that stage yet, but the price and CapEx for a PV installation since the FiT came in has fallen radically, and I suspect it will continue to fall.

How much of an obstacle are agreements?

I don't think rooftops have taken off in many cases because the landlord tenant relationship and property ownership instances needs both parties to agree terms somehow. I would've said it's partially an obstacle but if there was a decent financial return for undertaking it and you considered it an investment – if that's attractive enough – then they'd get on board with the paperwork and just get on with it.

At the moment we've got very low interest rates and zero inflation. At present energy prices, if you were selling your power, if you've got a bit of inflation then businesses would look at their energy consumption and look to save money by generating some themselves.

Do you think the solar industry doesn't place enough importance on the financial benefits of PV when pitching to businesses?

I think the financial aspects are always very key to driving a business or project forward because there aren't many parties in a global economy that can afford to do invest in something that doesn't pay you to do so. There needs to be that incentive and it needs to be clear and stable.

How much of an impact do you think 'lift-and-shift' and permitted development rights will have on the sector?

It just depends on the nature of the property ownership. Our team's view is that property ownership is one issue that has had a major affect on how rapidly PV has been deployed.