Homeowners around Australia caught on to solar pretty quickly and today more than 2 million household rooftops around the country host PV systems. But it’s a different story when you look down on our major cities and notice how little of that flat, vast expanse of industrial and commercial roofspace is paneled with the distinctive purple shade we associate with photovoltaics gear.

You’d think free daytime electricity would be an ideal match for the places we work, because a lot of the generation from residential solar systems is surplus to needs and exported to the grid – and yet our enormous, flat-roofed industrial zones are largely free of PV.

It’s something James Larratt, founder and CEO of solar company Solpod, thinks about whenever he’s on final approach. “When you’re landing at an airport and there are all these naked rooftops and you wonder, if the economics says solar is cheaper why aren’t I seeing more? It’s because the economics doesn’t reflect the choices people have.”

Too many empty roofs

Solpod’s solution to the problem comes in the form of pre-assembled “pods” of 10 or 12 solar panels that can be dropped into position by crane, cutting the usually arduous one-panel-at-a-time installation process. This means a PV system can be removed without too much fuss and redeployed at another site – if the owner moves – or popped back on in case it’s time to reroof.

When the pods of 72-cell panels are placed onto a rooftop they fold down into a tent shape, with modules on either side of a central spine angled at 10 degrees from the roof.

Non-penetrating solutions used by Solpod include clamps and an adhesive foot, developed with 3M. “It’s a very heavily engineered product,” Larratt says. “A lot of testing has gone into it and it’s performing really well.”

A 10-degree mounting angle allows for modules to enjoy a good wash in a downpour and for air to circulate underneath, to help moderate the temperature on hot days. Larratt says a typical PV panel will lose about one-third of a percentage point in performance for every degree above 25°C, so any boost to natural cooling will quicken payback. “In Australia in summer these panels can be up at 80°C,” he says, so performance may be about 18% lower. “There is a real drop off there.”

Prefabrication allows for systems to be removed easily, opening opportunities for renters or building owners who may want to redevelop or replace a roof inside the life of the solar system.

“Because we wanted to be redeployable we wanted to connect to the roof in a manner that was very easy to make good,” he says.

Occupants and owners may be nervous about voiding roof warranties and messing with the integrity of the roof, for good reason.

Lifetime mismatch

Solpod’s modular approach to commercial and industrial solar emerged as a solution to the problem business managers face, where they know rooftop PV is cheaper than the grid in an economic sense but in a commercial sense they can’t take advantage of it. “A 20-year economic analysis of the asset might be perfectly reasonable for the technology but it’s not for the customer who might only have a five-year lease at the site,” he says. “They’re likely to stay longer but they might only have a commitment for the next five years.”

While explaining his concept to landlords, Larratt found managers of large property portfolios were attracted to the idea of solar that can be shifted about fairly easily. For them, the flexibility of being able to redevelop a site without being hampered by permanent fixtures made immediate sense. “Property people want to do property deals,” he says, citing Solpod’s work with The GPT Group as an example.

Selling solar goes beyond articulating the benefits of owning an onsite electricity plant, and it’s possible for a deal to fall over when the prospective customer realises installing PV means drilling thousand holes in their roof. “There’s a real resistance to that; some will say it’s not rational, others will say it’s perfectly rational.”

The pods measure about four metres by five metres, and ideally are craned into place on warehouses, shopping centres, cool stores or offices with roofs pitched about 2 or 3 degrees, although the technology has been deployed at sites over six storeys. “We really want a simple roof,” Larratt says. “If it’s a very busy roof then the benefits we bring can be reduced.” So far, no systems have been removed.

Investment choices

A commitment to invest in solar might appear too risky for a few reasons: a tenant will worry that the lifetime of a PV system could be longer than they can commit to the business location; an owner won’t want to be out of pocket if the property is empty. “They don’t want to act as backstop and underwrite a future tenant they don’t know,” he says.

Even with the goodwill solar has in the community, it’s hard for any manager to choose among investment choices that could include: a capital investment in a non-core part of the business; a long-term financing arrangement that would cut operating expenses, typically longer than a decade, or; a shorter term financing arrangement, in return for higher operating expense.

“Those three choices are really difficult for any businessperson to say yes to,” he says. “By making it relocatable and redeployable, we break the connection between the finance term having to cover all of the asset payback.”

Presently, he says, the cost of taking a solar system off a roof is greater than the value of the system once it is removed. In that scenario an owner will want to see the PPA pay for the array, because you can’t take the array away.

Larratt says Solpod can offer PPAs of under five years for similar electricity rates to what some might be paying for 12-year arrangements. “It’s because we can bank a residual value at the end of that five years and we can redeploy the system,” he says. “We don’t need the first PPA to pay for the kit because we can economically redeploy the kit. We’re hoping that resonates with customers and opens up the market.”

Less time on the roof

PPAs can include make-good clauses – and additional expense at the end of the term to remove a PV system and plug all the holes in the roof with slightly bigger screws. Not so many solar systems have been removed around the country, but it will become more frequent as the lifetimes of arrays and rooftops reach their staggered maturities, with roofs requiring replacement every 30 or 40 years.

Many a solar salesperson has been close to inking a deal when the customer has remembered the roof sheeting is scheduled to be replaced in the next five to 10 years, “which pretty much means writing off the [PV] system,” Larratt says. “But with us it obviously doesn’t.”

Solar modules are awkward technology, two-square-metres of heavy, wind-catching gear that requires careful manoeuvring into place, sometimes on steeply angled rooftops. Best practice has two people carrying panels, Larratt says, “but that doesn’t always happen.” The Solpod solution, he says, represents a step up in safety standards.

Larratt has praise for the Australian Renewable Energy Agency, which committed $975,000 in funding to a project that is seeing Solpod-based systems installed on 25 sites in Victoria, NSW and Queensland, in partnership with ERM Power (a shareholder in Solpod), The GPT Group and NSW Property.

ERM Power sourced and contracted the property owners and is administering the delivery of the demonstration program, including billing the Solpod power purchase agreements, ARENA announced last year.

“It’s been brilliant,” Larratt says. “We’ve gone from where our targets were to where we’ve been able to exceed them. It’s a great story for ARENA, they’ve been a great support.”