Joburg has received applications for 32 MW of rooftop solar

25th September 2015 By: Terence Creamer - Creamer Media Editor

Joburg has received applications for 32 MW of rooftop solar

Photo by: Duane Daws

Johannesburg’s City Power estimates that there are already 4 MW of solar photovoltaic (PV) rooftop capacity in operation across the city and has revealed that it has received applications for the installation of a further 32 MW.

The largest rooftop installation is currently the 1.5 MW facility at the Clearwater Mall, in the northwestern suburbs of Johannesburg, which has been installed by Solareff on behalf of property group Hyprop Investments. However, several large banking groups have also invested in solar PV, as have some factories and schools.

City Power manager for demand- and supply-side management Paul Vermeulen tells Engineering News Online that 2.8 MW is currently officially registered with the utility, but that it is aware of a number of further installations.

In the absence of a clear national licensing and connection framework, City Power has developed policies that enable it to connect self-despatched generation capacity, with the proviso that the counterparty agrees to be bound by the terms of any future regulatory system implemented by the National Energy Regulator of South Africa (Nersa).

The regulator is currently finalising the framework, having already completed the public consultation phase, and Nersa electricity trading specialist Moefi Moroeng has indicated that it is aiming to publish the final regulations before the end of 2015.

Speaking at a seminar organised by the South African Property Owners Association and the South African Photovoltaic Industry Association, Moroeng disclosed that the regulations have been drafted and that Nersa is currently in consultations with the Department of Energy to seek its concurrence.

In the meantime, City Power is moving ahead with a strategy designed to accommodate residential and commercial rooftop developments, while safeguarding municipal revenue and network safety.

Vermeulen says the long-term vision is to fairly accommodate independent power producers (IPPs) on the city’s grid in a way that minimises grid defection and ensures that installations are safe.

“But we need the tariff to be in place to make sure that we still survive,” he adds, indicating that City Power plans to implement a service charge of 30c a day for every kilovolt-amp (kVA) connected.

“In other words, if you put a 1 kW system on your roof, the service charge will be about R11/kW a month. That amount partially makes up for the loss in revenue to the municipality and covers the expected increase in operating costs.”

The city is also prepared to pay IPPs “avoided Eskom costs” for any surplus electricity injected into the grid – a fee that could vary from 29c/kWh on a weekend to 56c/kWh during a weekday.

Where the tariff is applicable for ‘prosumers’ City Powerwill also want the facility housing the power plant to remain a net consumer of its electricity. But where IPPs intend to be purely generators, tariffs equal to the Eskom Megaflex tariff will be offered.

Vermeulen admits that the proposed service-charge solution remains unpopular with developers as it fails to incentivise rooftop installations and that the city is, therefore, considering various other options.

One possible alternative is to charge those customers consuming more than 500 kWh a month a 1.4c/kWh premium and to use the proceeds to neutralise the revenue and cost impacts on the city, without harming poorer consumers.

This premium is based on 20% of the total energy distributed being sourced from PV generation. About 300 000 of City Power’s 465 000 customers consume more than 500 kWh monthly, with an average middle-income household consuming about 1 200 kWh a month.

“It’s a relatively small amount, which would return us to a revenue neutral position,” Vermeulen explains, while acknowledging that it is still a long way from offering an incentive to IPPs.

The immediate focus, though, is on improving visibility of the rooftop installations already in place, as City Power is concerned about the safety implications of having installations that remain “below the radar”.

“The safety issue is the one that worries us the most. We don’t currently know whether installations have dangerous bypass switches in place that can obviate the islanding circuitry of inverters or whether the inverters themselves are up to scratch,” he says. The utility wants to be in a position to forewarn its technicians that there could be alternative suppliers to a substation when the grid fails.

City Power is far less concerned about substation capacity constraints, estimating that it is already in a position to accommodate up to 500 MW of rooftop supply without the threat of voltage instability.

“What we are hoping to do is to find a sweet spot that encourages connections, while sustaining the revenue needed to maintain and expand the grid, which is our core future asset,” Vermeulen explains.