The enormous paddocks of roofing that protect our cities’ warehouses and industry from occasional drizzle are largely naked of purple PV panels because of two wee problems: many networks won’t allow owners of C&I PV to export surplus solar energy, and the occupant businesses often don’t use enough electricity to account for much of a rooftop system.

But things are different at a Sydney warehouse where a huge PV system sends out much more power than the tenant can use and the local network has connected the owner up for energy export.

“In our case there are two connections,” says Epho head of business development Matt Scaddan. “We own the power system and the power output and any exports go directly to the NEM.”

The tenant in this case is logistics multinational DHL, operating a 31,000-square-metre warehouse dedicated to healthcare products in Horsley Park, western Sydney, leased from property group Goodman.

Epho and DHL have a power purchase agreement to supply the site a minimum annual volume of electricity from the 1.7MW rooftop system, with the condition that excess solar can be sold in the wholesale market via the Endeavour Energy network.

The dynamic switching between tenant and NEM is enabled by an algorithm developed with Siemens that bases its decisions on solar PV output, the electricity wholesale market and tenant demand. Epho has dubbed this form of onsite generation a Bright Thinkers Power Station, and it has plans to expand the concept wherever possible.

Power in the cities

Vast rooftops are not always positively correlated to occupants’ energy needs, of course, and the potential for industrial zones in cities to host utility-scale PV plants has long been hobbled by local networks’ limitations around exports. You can’t send too much solar energy out, they say, because voltage levels can cause bad things to happen. But Epho managing director Oliver Hartley says the Bright Thinkers Power Station solution shows a way around the problem – in many places, not all.

“These urban power stations can be 1MW, 2MW, 3MW, possibly up to 5MW, and they do not suffer from marginal loss factors, which is a huge advantage,” Hartley says. “Secondly, these projects can be rolled out quickly. We don’t have to do environmental studies; general DAs are easier to get. There is the potential for rollouts where … all of a sudden you have 100MW.”

Industrial PV has a role to play when it comes to kickstarting the economy with renewable energy, Hartley says, and even better if the incentive problem between landlord and tenant can be overcome. Access to the wholesale energy market is a benefit, if the seller is suitably agile.

“Dynamic shifting can happen in minutes; very quickly we can shift shares between what we send to the wholesale market and what we send to the tenant.” Epho is working on a forecasting model to refine the decision-making process, Hartley says.

“There are also instances where the NEM price might be peaking and if we’re generating solar at the time we might make a decision to direct more power to the NEM rather than to the site, because it might be more valuable,” Scaddan says.

Epho specialises in solar for large property companies and Hartley estimates there is 30-50GW of potential sites for its Bright Thinkers application.

Outsized and proud of it

The rooftop PV system at the DHL-Goodman site was outsized to test the potential for Epho’s Bright Thinkers Power Station; Scaddan estimates a 700-800kW system would have sufficed to fulfill the client’s needs alone. “There was no need to commit to a larger solar system up front, but that’s what the Bright Thinkers Power Station solved – we’ve got that excess capacity [if the client increases its load],” Scaddan says.

The PPA is for the term of DHL’s lease and Epho has a separate agreement with the landlord that outlasts DHL’s current lease. “If they leave the site we still have access to the solar that’s generated,” Scaddan says. Epho won’t share its estimate of a payback period for the project. Revenue comes in three streams: the PPA, the sale of large-scale generation certificates and sales into the wholesale energy market. Outgoings include roof rental and ongoing operation and maintenance costs.

The system doesn’t include storage but Hartley says it’s on the drawing board. “We could integrate a battery system if we wanted to and take advantage of arbitrage, demand reduction, peak shaving – it’s all possible, we’ve got that flexibility. That’s why we are excited about it. An urban power station opens up these flexibilities.”