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Case Study

Weak grid: sustainable production with PV hybrid systems

Setting the scene

Rwanda, in East Africa, has seen steady economic growth over recent decades. It has great untapped potential for renewable energy, with high solar radiation and plenty of opportunity for hydro power.

However, much of the rural population remains without electricity and for those people and businesses lucky enough to be connected to the grid, supply can be intermittent and unpredictable.

This is where renewable energy is playing a fundamental role in Rwanda’s future, and The Sorwathe Tea Factory is a great example of this. Here, we’ve installed a bespoke solar diesel hybrid system for Rwanda’s only FAIRTRADE-certified tea factory, which every year produces an incredible 3.2 million kg of tea.

This project is part of the worldwide ‘dena’ Renewable Energy Solutions Programme coordinated by Deutsche Energie-Agentur (dena), the German Energy Agency, and co-financed by the German Federal Ministry for Economic Affairs and Energy.

What we did

Only electricity from the national grid or diesel generators had been used for tea production previously. This created issues with reliability and was costly both economically and environmentally.

But to introduce renewables into the energy mix, we needed to design a tailored system to meet the Tea factory’s key energy requirements - a stable and secure supply.

To deliver this project, we worked in close partnership with our specialist subsidiary company, OneShore Energy, now fully incorporated into BayWa r.e. The team specialises in the design of solar diesel hybrid systems and has a huge amount of experience.

This enabled us to create the perfect solution for the Tea factory, which brought together OneShore’s advanced software-based analysis and planning tools, and BayWa r.e.’s extensive portfolio of photovoltaic (PV) products.

To ensure we designed the most efficient system, the entire process was digitised using an intelligent measurement and software solution. This involved analysing the actual electrical loads, as well as the complete design of the hybrid system and ensured the optimal energy supply mix.

In this way, we were able to guarantee that electricity supplied from the PV system, the public power grid and the diesel generators, at all times, covered the tea factory’s total energy requirements of 72,000 kWh.

Getting the result

The installation of the solar diesel hybrid system at the Sorwathe Tea Factory, is the first ever weak-grid project delivered in Rwanda.

Thanks to the digitally controlled system, our installation not only saves nearly 22,000 kg of CO2 each year, but it has significantly reduced the factory’s diesel fuel consumption and reliance on Rwanda’s national grid. This translates into cost savings of up to €11,500 per year.

The Tea Factory now has a more sustainable, round the clock secure power supply. Production is on the rise and profits on the increase. That’s good news for the tea factory, the country’s economy and the people it employs.

The PV diesel hybrid system is the optimum solution for our tea factory because it significantly increases the proportion of environmentally responsible solar power […]. We are delighted to be able to establish Sorwathe as a producer of on-site cleaner, more innovative energy in East Africa.

Rohith Peiris
General director, Sorwathe Ltd

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