Condor Solar News Blog

Learning from Cape Town’s largest PV rooftop installation: Black River Park

Black River Park’s solar PV installation is one of the largest rooftop installations in the country (Image Source: Jonathan Ramayia)

In one of Cape Town’s oldest suburbs, Observatory, lies an uber-modern office park powered by cutting edge solar photovoltaic technology.

The Black River Park (BRP) solar PV plant, which currently stands at a capacity of 700 kWp adds to a growing number of commercial solar PV installations popping up on roofs across the Mother City. 

The project is currently in Phase 2 which will increase its capacity by a further 500 kWp making it the largest Solar PV Plant in the country.

The plant employs the use of polycrystalline solar PV, a mature technology chosen for its reliability and cost-effectiveness.

The first phase saw 2,875 panels installed, with a further 2,050 panels being installed in Phase 2.

The entire system will be larger in area than a rugby field, topping 8000 square metres and is predicted to generate 1.9 million GWh per annum, or enough power for 1000 average sized houses.

Apart from its size, the project is unique because it sets a precedent for office park property developers who seek to attract rental in a number of competitive areas, one of which being the provision of a ‘greener’ office environment.

“There is a benefit for tenants to say they operate from a greener production facility."

"It seems to be a major consideration for prospective tenants looking for space as well as for our current tenants, come renewal time, “says Matt Rich, Facilities Manager of Black River Park.

The tenants are a mix of companies that include Brandhouse, Dimension Data, the Naartjie Company, Adidas and the Green Building Council of South Africa (GBCSA).
Financial feasibility

The project when completed will cost R22 million in total and is being overseen by SOLA Future Energy with the installation and electrics being handled by Besamandla.

In spite of the high capital costs of the entire project, there are a number of incentives the project either took advantage of or hopes to capitalise on in the future, all contributing to its financial feasibility.

Phase 1 received the Eskom renewable energy subsidy which helped finance a proportion of the project through the Standard Offer programme.

According to Rich, Phase 2 will have to stand on its own legs as the Eskom subsidy for renewable energy projects has run out.

BRP is also currently investigating selling carbon credits from the project but concedes that the actual exchange of carbon credits will be about two years away.

“It’s not the reason we went for the project but selling carbon credits will definitely help the business case for future development,” said Rich.

The main financial benefits for BRP is that its electricity bill has been reduced by a fifth due to the majority of the electricity being produced at the same time as it is needed explains Rich, “... our consumption, or demand curve fits in nicely with energy production from the installation”.

The major usage at the office park, which house more than 110 tenants in over 76,000 m2 of lettable space, is air-conditioning and this has helped the financial feasibility of the project.

“Everyone wants to turn on their air-conditioning when the sun is out which luckily for us is when we are producing the most amount of electricity,” he explained.

With the completion of Phase 2 the electricity savings is set to almost double.


North Park roof installation (Image Source: Black River Park)

Limitations of the system

The size of Phase 1 would have been bigger, however the North and South Parks of BRP have separate connections to the electricity grid and the City of Cape Town does not currently allow electricity to be wheeled across the grid in circumstances like this.  

“The North Park is on one Erf but has the most conducive roof space to take the PV installation. We are limited for roof space on the South Park which is on a separate Erf. This is where the current installation of smaller Phase 2 is taking place,” explains Rich. 

Another significant constraint is that since the BRP Solar PV system is connected to the City of Cape Town electricity grid and does not have its own battery it cannot be used during a power outage. 

Grid-connected system needs to turn off when the grid goes down, known as anti-islanding, for the safety of municipal workers who might be trying to repair power outages, or doing routine maintenance.

Rich has been in discussion with service providers to work out how to use the electricity generated by the  PV system during times of power outages.

“It could take a re-wiring of the office park and even then we would only run the basic essentials like plugs and lighting for our tenants to operate their businesses,” said Rich.

He added that there hasn’t been that many outages since the rolling blackouts of 2008 but if blackouts start to occur more frequently it would make sense for BRP to investigate further for the benefit of their tenants. 

BRP management has made sure to inform every new tenant about anti-islanding in order for there to be no false expectations of what the PV system is able to deliver in times of power outages.

BRP is also not able to export any excess energy  that is produced, e.g. during weekends and public holidays, to  the City of Cape Town’s grid. This is because the City of Cape Town has not yet finalised a net-metering process.

Net metering refers to the practice allowing users with their own energy generation facilities to both draw energy from the grid and to generate onto the grid and to then charge uses for the amount of energy they draw from the grid minus the amount they have exported.

This limitation could soon change with Phase 2 of the project and BRP may become the first commercially approved net-metering project in Cape Town. It’s understood however, that the City will seek to only approve projects where consumption is equal to or more than the amount of electricity generated.

This will however not be an obstacle for BRP as the Solar PV system can only produce electricity during the day and there is demand for night time usage, for lighting and for tenants who sometimes work at night.

Another solar PV rooftop project located 12 km north east of BRP is theVodacom Century City solar PV installation which faces the same problem of ‘wasted’ electricity and is considering  building an ice maker for their air-conditioning requirements.

“We’ve looked into this, but because of the make-up of this business park and the way it runs, we don’t control tenants usage, there isn’t a centralised air-con plant, so it’s not possible to have a big centralised chiller room as there are too many smaller units,” said Rich.

He added that companies like Vodacom or hospitals e.g. could set a standard for temperature for example but that it would be difficult for BRP to do so with so many different businesses at the park as they each have different demands.


Central Park roof installation (Image Source: Black River Park)

Performance and maintenance contracts

A performance contract was signed between Aurora and BRP which guarantees the amount of electricity that will be produced each year, given historical weather data and the performance of the PV system.

A remote monitoring system accessible by Aurora allows them to ensure they are achieving the targets stipulated in the performance contract.

"... if they [Aurora] see that they’re not getting that performance, there’s going to be an issue…so they are often out here making sure everything’s going according to what they have forecasted,” said Rich.

Luckily for Aurora it’s going better than expected with plant running at 118% production at the moment, or 18% more production than the given historical weather data.

“Obviously we are in the middle of summer, the figures might be slightly inflated, and going into winter, may normalise a little,” added Rich.

The maintenance contract which cost in the region of R230,000 per annum has been important for both BRP and Aurora.

“As a property manager I don’t know the first thing about how to maintain a PV system, which is quite a substantial asset on our roof,” said Rich.

The maintenance involves getting the panels cleaned of salt which is a problem in the area as well as bird faeces and also makes sure the system is running smoothly without interruption.

According to Rich if one panel is obscured by the sun or if a module goes offline, this affects the entire 24 module chain.  This problem was observed last year when a small antenna cast a shadow on one of the panels.

“If we didn’t have the maintenance contract in place it would have probably taken a year for us to figure out, we’re not up there, to see the shading of strings and such, the whole thing is monitored off site.

As soon as there’s a problem they [Aurora] are the ones telling us they’re coming to do some fixes to this that or the other, which is one of the benefits of a full remote monitoring system,” said Rich.

Another benefit of the monitoring system is that it’s helped engage tenants with the project as BRP management has displayed the performance of the system onto big screens at the entrance of North Park.

The display shows consumption and production graphs for the last week as well as the carbon that has been saved.

The project has proven an important impetus for other projects at BRP that aren’t related to solar PV explains Rich.

“This whole greening journey we’re going on has stemmed from the solar PV project, it’s not only got the benefit of the cost savings, the idea of being green and the efficiencies of the park, it’s pushed us into this greening way of thinking.”

Apart from recycling and water initiatives BRP is embarking on a training and awareness programme for tenants which focusses on behavioural changes such as switching off lights and air-conditioning when not in use.

But it is their landmark solar PV installation that will put them in good stead for their application to become a green-star rated building later this year, within GBCSA’s pilot toolkit for existing buildings.


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