TESVOLT supplies Rwanda with the world’s largest off-grid battery system


The German commercial storage system manufacturer Tesvolt has been awarded the contract to supply the world’s largest decentralized off-grid storage system, which acts as a mini-grid during power cuts. The company is set to deliver a lithium storage system with a total capacity of 2.68 megawatt-hours (MWh) which will provide water pumps in an agricultural project in Rwanda’s Eastern Province with emergency power. The 3.3 MW solar power plant and the storage system are being engineered and constructed by the international system integrator IdeemaSun energy.

High charging speeds at low costs

“In Rwanda, the power supply fails three or four times a day for between 5 and 45 minutes. For this reason, an important criterion in the call for tender was that the storage system is able to absorb electricity from the PV power plant and release it again as quickly as possible. Only very powerful off-grid storage systems can supply the necessary emergency power several times per day, and there are only a few storage systems on the market which meet these requirements”, explains Simon Schandert, Director of Engineering at Tesvolt. “A further selection criterion was the necessity for the entire storage solution to be as reasonably priced as possible.”

Tesvolt has developed storage systems which use prismatic battery cells, which enable high charging speeds through their particular design and chemical composition. The intelligent control system ensures that each individual cell is charged and discharged at the optimal rate for a particularly long service life.

Tesvolt battery storage container TLC 500 with 0,5 MWh capacity

134 lithium storage systems for water pumps

Tesvolt is set to supply a total of 134 fully assembled lithium storage systems for the 44 water pumps. The storage system will supply the irrigation project with clean and safe emergency power, also boosting yields in local agriculture. This should improve the living conditions of around 2,000 farmers, who currently live in extreme poverty. In total, 402 Sunny Island charge controllers from SMA are to be deployed for the project. In the event of power cuts, the storage system will act as a mini-grid, enabling the PV power plant to continue running.

Every cell in the storage system is monitored

The Tesvolt battery management system monitors each individual cell when the system is in operation so that any damaged cells are identified before they completely fail. If a cell is defective, the installer only needs to exchange that single cell, unlike in conventional storage systems where the entire battery block has to be replaced.

Suitable for all applications

Tesvolt offers storage systems in six different size categories with capacities ranging from 10 to 60 kWh. They can be combined flexibly depending on the desired storage size – for example, to form a large-scale storage system with a capacity of 1 MWh, which Tesvolt supplies as a ready-to-use container. The client also can decide how quickly the storage system should charge. For high charging speeds, the storage system is combined with several Sunny Island charge controllers from SMA. The greater the number of stand-alone inverters and the higher their output, the greater the amount of energy stored and the faster the system can supply it. Regardless of whether the storage system is connected to the power grid, this highly flexible system concept makes Tesvolt storage systems ideally suited to any application.

Tesvolt will be introducing its storage systems at Intersolar Europe in Munich from June 22–24, 2016.


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