Oct 2017

Robben Island battery bank

Robben Island’s 666.4 kW solar PV and battery storage microgrid

Last week, the Minister of Tourism opened the Robben Island solar PV microgrid, designed and constructed by SOLA Future Energy. This system, incorporating one of the southern Hemisphere’s largest battery banks, is made of 1960 mono crystalline solar modules, ready to produce 666.4 kW of power and 2420 lithium-ion battery cells, able to store 837 kWh worth of electricity and supply 500 kW worth of peak power.

Designing a smart grid

SOLA Future Energy designed Robben Island’s Microgrid over the course of two months. Designing the PV plant incorporated several phases, including the replacement of a mini-substation to adequately incorporate PV into Robben Island’s existing grid, designing of the ground-mounted solar farm and placement, the battery bank and controls.

Phase 1 – Understanding the island’s energy requirements and solar resource

Robben Island Tourism - Robben Island Solar PV System

Robben Island attracts thousands of tourists each day

The first phase of the designing a solar PV microgrid was to understand the energy requirements of the island – and what solar resource is available. With thousands of tourists visiting Robben Island each day, as well as 100 staff living permanently on the island, a lighthouse and a desalination plant, the island’s energy requirements are quite significant. Understanding these requirements was the first phase to knowing what type and size of system to design.

Typically, when designing rooftop solar systems, it is important to consider shading from other buildings or large trees, but with Robben Island’s placement and shrubby vegetation, the solar resource is excellent and relatively undisturbed. In addition, the ability to place the modules at a fixed-tilt axis in a north facing area, made them ideal for solar penetration, right into the late afternoon.

Phase 2 – Understanding the existing grid and how to incorporate into it

robben island solar power supply

Robben Island power supply was traditionally provided by diesel generators. Last week, the Island officially announced it’s conversion to solar energy

Solar PV usually powers a building directly by turning its Direct Current electricity (DC) into Alternating Current electricity (AC), through solar inverters. This power is usually supplied in 400kV size, which is the power that typically supplies plug-points and electric outlets in buildings. However, incorporating into an energy grid requires a different kind of connection.

Robben Island’s energy grid runs off of a historically-erected 11kV line. In order to incorporate the PV system into the island’s grid (as opposed to, for example, a single building), a mini-substation needed to be designed and built in order to convert the PV plant’s supply of 400 kV to the grid’s 11kV. This substation replaced one of the island’s existing, but too small, substations. Once erected, it allowed the PV farm to feed into the island’s grid.

Phase 3 – Modelling and simulating the PV and battery resource

Microgrid performance on Robben Island Solar Microgrid

Data insight helps to monitor the microgrid’s performance

Once the solar farm was designed, based on the energy needs of the island, the design needed to incorporate the battery system to store excess solar power, taking into account the scope of the project. The battery bank is made up of 2420 lithium-ion battery cells. Like cell phone or laptop batteries, lithium-ion batteries have a long life and have a higher threshold to discharge and charge with larger power. Unlike their lead acid counterparts, lithium-ion batteries can use up to 96% of their capacity, making them a highly efficient choice to support the longevity of the solar PV farm, which will last over 25 years.

A large part of designing the battery system to incorporate fully with PV is the programming of the actual microgrid. The programming consists of scheduling the generators to switch off when the batteries reach 30% State of Charge (SOC). When the batteries reach 15% SOC, the generators are scheduled to switch on, making sure that there is a continuous source of power on the island. The wireless system between the three different components allows the batteries to “talk” to the PV. This decision-making ability, and intelligent control in each device, makes the microgrid a smart grid that ensures seamless power to the island.

Helping not only the efficiency, but the quality, of energy supply

Diesel generators on Robben Island Solar System

Diesel generators to provide energy when battery bank is depleted

One of the unexpected outcomes for Robben Island is a better quality energy supply for the island’s operations. Previously, the quality of supply had peaks and troughs, meaning that equipment could be affected by unbalanced supply. However, the new battery inverters are able to stabilise the grid, making the power better quality overall, and in turn affect equipment and machinery less.

Although the microgrid contains diesel generators, the Robben Island microgrid is unique because it does not rely on the diesel generators to function. Usually, solar PV works by attaching to an existing grid – or diesel generators. However, with a special inverter, the microgrid contains a virtual generator machine (VGM), which allows the PV to run without any generators at all.

Robben Island Solar Energy Microgrid Infographic

In conclusion

SOLA Future Energy has carried out the design and construction over the last year and a half on Robben Island. Although the design of the system took about two months of non-stop design time, there were several other considerations in working on the World Heritage Site. The video of the Robben Island Solar Project tells the story of the island’s symbolic transformation and its relevance as a microcosm of South Africa. The future of Africa is powered by the sun, and we’re there to make it happen.

Robben Island Tourism

Video clip shows the transformation of Robben Island into a beacon of hope

When SOLA found out that they had won the contract to build a solar PV microgrid on Robben Island, commissioned by the National Department of Tourism, they were determined to spread the story of the project far and wide. With the help of video-experts Lima Bean, they created a short film that tells the story of Robben Island’s transformation.

A perfect set for a transformation story

Robben Island is known for many things, but particularly for being world heritage site on the tip of South Africa, and “a symbol of the triumph of the human spirit over adversity”. It is also known for its beautiful, stark scenery and ecological diversity. Yet the island still requires energy – the ongoing tourism, desalination plant, and local community use 2 million kWh per year. This power was historically supplied only by diesel generators, but since July 2017, is being supplied by the sun. It is the perfect setting for a story of transformation and hope.

Robben Island solar PV microgrid

Robben Island solar PV microgrid

A symbolic transformation

“We wanted to show that Robben Island is a great example of how a difficult historical context does not prevent a brighter future,” said James Bisset, the short film’s director. A key component to the symbolic side of the story was the input from Vusumzi Mcongo, an ex-political prisoner who arrived on Robben Island in 1978. Now 63 years old, Mr Mcongo still lives on Robben Island, and works in the Robben Island Museum, taking tours through the prison. “I have a passion for this place,” he states.

As someone who not only works, but also lives on the island, Mr Mcongo is part of the new energy story: he is part of Robben Island’s transformation from old power to the new, and will benefit from the new system. Robben Island has a difficult history – one of banishment and imprisonment – but, like Mr Mcongo, the future of the island is one of hope rather than pain.

“Telling the story of the Robben Island Microgrid was very important to us,” SOLA CEO Dom Wills stated. “The transformation of Robben Island is symbolic: it shows that there is hope and inspiration for South Africa and potential for innovation in the future. We want South Africa and the region to see that affordable, clean energy is here today.”

Robben Island Tourism

Robben Island attracts thousands of tourists each day

Solar PV and batteries: the future of energy

The Robben Island solar PV microgrid is a story of hope because of the technological innovation at its core. Solar energy uses the sun’s power to create electricity. Traditionally, solar PV works during the day and requires additional power sources at night, when the sun doesn’t shine. However, with the strides in battery technology over the last few years, battery storage has huge potential to change the game and make solar a viable option for going completely off-grid.

The Robben Island solar microgrid is an example of such a game-changer. The generators on the island historically used an expensive and fossil resource, diesel, which was shipped to the island in order to generate the electricity required. The new solar microgrid stores the excess energy created by the sun in the middle of the day in lithium ion batteries, powering the island well into the night. By the time the generators kick in, the consumption of the energy is low, and ultimately Robben Island can significantly reduce its reliance on diesel, even during the winter months.

Robben Island solar PV construction

Construction of the Robben Island solar PV farm

Partnerships make the video possible

Suppliers to the project partnered with SOLA and Lima Bean to make the creation of the video story possible. ABB, the inverter supplier to the project, and Canadian Solar, who supplied the solar modules, were both key partners in enabling the video to take place. “Making a video like this is not cheap, and we were grateful for the support of our partners to make the video possible,” said Dom Wills.

The Robben Island solar microgrid shows the power of solar PV and batteries

It has been almost a year and a half since the Robben Island Solar Microgrid project was awarded to SOLA Future Energy. After a thorough process of designing, planning and implementing, the project has been launched – and is a demonstration of how solar PV, combined with batteries, can make an excellent combination. This blog post describes just why the solar microgrid is so effective, and how the rest of South Africa can follow suit.

A microgrid on a historic monument

Many people know Robben Island for its reputation as the prison that held several high-profile political prisoners such as Walter Sisulu, Ahmed Kathrada and Nelson Mandela. Over the years, the island has also been a leper colony and a host site of WW2 garrisons. The island, therefore, has a rich political history – one which draws the thousands of tourists to its shores daily.

In addition to the historical significance, Robben island is also a biodiversity hotspot, with several bird species finding refuge and breeding grounds on the rocky shore. The African penguin – an endangered bird found only on the southern coast of Africa – also calls the island home.

Robben Island Solar Microgrid protects islands biological diversity - Penguins

Robben Island is a world heritage site with biological diversity

Energy to Robben Island has historically been supplied by diesel generators. To fulfil the energy requirements of the island, around 600 000 litres of diesel were consumed on an annual basis – at great cost to the island’s administration, and at great cost to the sensitive environment on the island.

The solar microgrid was commissioned by the National Department of Tourism in order to promote sustainable tourism at key monuments around South Africa, as part of their Tourism Incentive Programme. The microgrid, consisting of a 666.4 kW solar farm, 837 kW powerstore and multiple controllers, will move the island away from its reliance on diesel generators and toward the sustainable resource of the sun.

The World Heritage status of the island made it a very sensitive area to carry out construction, and environmental and political considerations meant that the site for the PV farm was carefully chosen. SOLA staff had to also be sent for training to handle penguins, snakes and wildlife and how to handle archaeological artifacts that might be discovered underground.

What’s so great about a solar microgrid?

A combination of tourism, desalination plant and local community means that Robben Island uses over 2 Million kWh of electricity annually. The solar microgrid consists of several elements that will produce almost 1Million kWh of electricity annually, significantly reducing costs of buying diesel, ferrying it to the island and burning it for electricity generation.

The solar microgrid uses the most abundant resource on the island – the sun – and converts this energy seamlessly into electricity, which can be used for operations. In combination, the battery system stores any excess energy produced by the sun, for use during the night or on cloudy days. If both the battery system and the sun are low, the smart microgrid controllers trigger the diesel generators to start up, ensuring that the island never experiences energy shortages or blackouts.

Robben Island Replace Diesel Generators With Solar Power PV Microgrid

Robben Island has historically used diesel generators to provide the power needed on the island.

The combination of solar and batteries, a revolutionary step, is the key aspect of the return on investment for the island. The solar microgrid will ensure that the island reduces its fossil fuel consumption dramatically, by nearly 250 000 litres of diesel per annum. This will result in a reduction the Island’s carbon emissions by 820 tons, as well as a significant monetary saving. The system will last over 20 years.

How a smart solar microgrid works

Usually, solar systems are grid-tied – meaning that they supplement power supply and remain connected to the central electricity grid. Some also produce excess power which feeds back into the grid. A microgrid, in contrast, works independent of a centralised electricity grid, yet retains the functionality of it. This means that it contains multiple controllers that switch power sources as and when necessary, without ever interrupting the power supply.

In the Robben Island Microgrid, there are three key power production aspects. The first of these is a solar farm, consisting of 1960 mono-crystalline modules that produces 666.4 kW of power.

Robben Island Solar Microgrid Uses 1960 solar modules

1960 solar modules to provide energy on Robben Island

The second is a battery bank, consisting of 2420 lithium-ion battery cells, ready to store 837 kWh worth of electricity and supply 500 kV worth of peak power.

Robben Island Solar Power PV Microgrid battery bank

2420 lithium-ion batteries store solar energy for use after hours

The third aspect is the diesel generators, which supply power to the island when the solar farm is not producing energy (for example at night), and the battery bank is depleted.

Old Diesel generators on Robben Island Replaced With Solar Power

Diesel generators to provide energy when battery bank is depleted

Combined, these three power production elements, coupled with a set of smart controllers, supply Robben Island power – all of the time.

Microgrid controls a smart approach to energy management

The microgrid control system is based on a distributed intelligence approach which ensures that the grid behaves smartly for seamless power production. Each of the points of power production have a logic controller that controls the power output at each of these points, whilst reporting back to the other controllers. The system monitors the current load by adding the current production of each of the power sources; each of the controllers then adds a safety factor to the current load and always makes sure it has enough power, immediately available, to supply the load and handle sudden increases in load, such as the operation of the 200 kW desalination plant. The only centralised component in the system is a data-collection system, similar to a small SCADA (Supervisory Control and Data Acquisition), which allows for set points to be altered and measured values to be recorded.

The potential of solar and batteries: a Robben Island case study

Solar PV has long been a more cost-effective energy source than the central grid in South Africa, but it’s the combination of solar with batteries that will make the technology truly disruptive, as it has the potential to make the centralised grid redundant. The Robben Island Microgrid is a great case study to explore the true value of solar PV and battery combinations, because it is already independent of the central grid. During its first two months of operation, the island produced 187 000 kWh clean electricity through solar power, resulting in 53 685 litres of diesel being saved, an equivalent of 495 tons CO2 emissions.

Solar PV Microgrid performance on Robben Island

Data insight helps to monitor the microgrid’s performance

The above graph shows Robben Island’s energy demand (blue line), supported by the generator through the evening. Around 6.30 am, the solar system (green line) starts to produce power, and by 9.30 am, the solar system starts to supply the entire island’s energy demand. By 10am, the solar power starts to surpass the island’s demand, and charges the batteries. Once the batteries are full, the solar power curtails to meet the demand of the island. Once the power starts to go down at 6pm, the batteries are activated and start to discharge, finishing their power around 8.30 pm when the generators start up again.

This graph demonstrates that the solar farm can easily meet – and exceed – the needs of the island during hours of light, even in winter. The rate at which the battery bank charges suggests that an even bigger battery bank could be possible – and the island could rely even less on the diesel generators.

The rapidly decreasing price of battery tech

Based on the above graph, it is clear that an even bigger battery bank on Robben Island would further decrease the already substantially reduced spend on diesel and its accompanied environmental degradation. As such, how can projects start to install solar PV and batteries to meet enough demand to go off grid entirely? The future is closer than we think.

In 2016, the costs of a lithium-ion battery cell had come down 73% from 7 years prior. Even during the building of the project over 12 months, the cost of the tech went down significantly. The graph below, published by Bloomberg New Energy Finance, demonstrates the cost reduction of batteries over the last 7 years.

decreasing costs of lithium-ion batteries with Solar PV Microgrids

Source: Bloomberg New Energy Finance

 Conclusion: how South Africans can learn from Robben Island’s Example

Robben Island has a difficult history – one of banishment and pain – yet today it serves as a heritage site and a reminder to thousands of the triumph of the human spirit over adversity. In a similar vein, Robben Island’s energy history is one marred by reliance on fossil fuels and environmental degradation. The Robben Island solar microgrid shows an inspiring example of the way in which communities can adopt clean, efficient and more affordable energy – to the benefit of the local community and the surrounding environment.

“It’s been inspiring to work on a project like Robben Island,” said SOLA CEO, Dom Wills. “The island is in many ways a microcosm of South Africa, and we hope that its example will inspire other African communities to follow suit. Adopting clean energy is not only possible – it is now affordable. What Robben Island has taught us is that the future of efficient energy is within our reach.”

Robben Island Microgrid Infographic

Do you know of a community who could benefit from solar microgrid technology? Contact us or use our solar calculator to find out if it is viable. The future of Africa is powered by the sun.