FAQ

Here you will find answers to the most frequently asked questions about our company and our products.

Peak load capping in off-grid applications: How does it work?

Our TS HV high voltage system can be combined with a diesel generator for use in hybrid off-grid systems, where it can be used to cap peak loads and reduce diesel consumption. In this application, the diesel generator supplies voltage for the system and the TS HV optimizes the operating characteristics of the generator in the diesel hybrid system in order to use as little diesel as possible. This increases efficiency and extends the service life of the generator.

Service life and cycles?

TESVOLT batteries have a chemical service life of over 30 years. This means that the storage system should function for at least 30 years on the basis of its technological configuration alone. Depending on the application, the service life of the battery is more than 8,000 cycles at a DOD of 100%. These figures have been confirmed in comprehensive tests.

Tesvolt provides detailed warranties for its storage systems. What exactly is covered and for how long?

TESVOLT offers a 10-year performance warranty on its batteries (reinsured by Samsung SDI). This includes the industry’s first ever DC efficiency warranty.

TESVOLT also offers a transparent cycle warranty which depends on the C-rate, temperature and frequencies in each individual application.

In addition, all TESVOLT components come with a 5-year electronics insurance (reinsured by a reputable German insurance company).

TESVOLT batteries have a chemical service life of over 30 years.

How can operators ensure that the storage system runs within the temperature range covered by the warranty? Does this require the system to have a permanent internet connection to monitor the temperature?

Our transparent warranties allow each customer to decide for themselves whether they would like to operate their storage system in the Arctic Circle or in the desert. The storage systems take temperature readings which are continuously charted, even without an internet connection.

How do partial discharges affect the guaranteed number of cycles?

A cycle is defined as the discharge and recharge of all the energy in a cell (100% DOD). Microcycles (partial discharges) are accumulated into full cycles.

What is the ideal temperature range at the installation site?

Ideal temperatures for the storage system are between 15°C and 28°C. Due to the prismatic construction of our cells and the use of NMC technology, thermal loads are lower during the charging and discharging process. That’s why our warranties cover a broader range of temperatures.

To what extent do rapid charges and discharges as well as deep discharges of up to 100% stress the storage system? If the storage system is subjected to less stress, does this extend its service life?

TESVOLT uses Samsung SDI cells, which were developed for the automotive industry and are designed to withstand heavy loads. It makes little difference whether the cell is discharged at a rate of 0.3C or 2C. It is important that lithium batteries are continuously cycled, i.e. charged and discharged. Completely discharging 100% of the energy is not critical. Lithium cells age more quickly at high states of charge.

What are the advantages of a TS HV 70 high voltage storage system?

System efficiency increases. Due to higher voltages, significantly less electricity is needed, which makes it possible to reduce the cross sections of the cables, thereby also reducing losses in the cables. For example: at an output of 24 kW, the current is approx. 500 A at 48 V; accordingly, a copper cross section of at least 120 mm2 is needed. At an output of 24 kW, the current at 700 V is only approx. 35 A, so a copper cross section of 10 mm2 is sufficient.

In addition, the battery inverters are significantly more efficient thanks to their transformerless design. This makes it possible to achieve a round-trip efficiency from around 80% to over 90% for the entire system (charge controller + battery and hardware).

What are the response times and settling time of the TS HV 70?

The response time is approx. 20 ms and the settling time does not exceed 200 ms. During these 200 ms it is still possible to demand 100% power from the system. This means that the storage system is suitable for balancing power applications.

Is there a simple empirical formula used to calculate electricity generation costs of under 10 cents/kWh with a photovoltaic installation and a TESVOLT storage system?

To calculate production costs (electricity generation costs), i.e. the cost per kWh of self-generated electricity for the operator, the total investment costs are divided by the power generated over the entire service life of the PV installation, wind turbine, CHP plant etc. This is because the storage system is charged by the energy source and increases self-consumption.

When these figures are entered into the empirical formula shown below, the result is a price of 10 euro cents per stored kilowatt-hour. A detailed representation that takes into account inflation, degradation, the EEG levy, maintenance, insurance and metering costs, etc. can be transparently calculated using PV-Kalk, an online tool for calculating PV profitability (only available in German).

Storage temperature of the battery modules?

The battery modules can be stored at temperatures between -20°C and 60°C without any loss in operational capability.

Does the monitoring system really depict each cell individually?

Yes – during monitoring, the voltage of each cell is measured individually. These values are then used to determine the state of charge (SOC) and the state of health (SOH).

How does battery recycling work?

The batteries are recycled by the GRS Batterien Foundation, which operates a common collection scheme for lithium batteries. As part of this program, TESVOLT pays a fee for each battery module sold. GRS Batterien guarantees that the battery module and the Active Battery Optimizer will be collected.

Currently this program is only available in Germany, but an expansion to include all of Europe as well as North America and Australia is planned from 2018.

How does the TS 48 volt system achieve standby consumption of one watt?

The system has been technically optimized to minimize losses. The single watt is consumed by a processor. Instead of using relays, which have a holding current, the system relies on a static switch to isolate the battery from the charge controller. The power dissipation of the static switch is calculated by the equation P=I2 * R. If no current is flowing, the static switch does not require any power. Moreover the system forgoes passive balancing, which is prone to losses, in favour of an energy-efficient active balancing process, which is the only of its kind worldwide (Active Battery Optimizer – made by TESVOLT).

Can the battery modules and racks be expanded years later?

Our TS and TS HV 70 storage systems not only offer flexible configuration options at the moment of purchase – thanks to the innovative Active Battery Optimizer technology, the capacity can also be expanded years later.

The Active Battery Optimizer optimizes all the cells within the battery modules, as well as the individual battery modules in relation to one another. This process is the only one of its kind worldwide and, for the first time, ensures that the system can be adjusted to reflect customer requirements, making an investment in a modular lithium storage system both safe and sustainable.

What is the Active Battery Optimizer (ABO)?

Der Active Battery Optimizer (ABO) ist eine technologische Innovation Made in Germany by TESVOLT.

The Active Battery Optimizer (ABO) is a technological innovation “Made in Germany” by TESVOLT. The ABO not only optimizes all the cells within the battery modules, but also the individual battery modules in relation to one another. This process is the only one of its kind worldwide and, for the first time, ensures that an investment in a modular lithium storage system is both safe and sustainable. The ABO is located on the front of each battery module.

What is the Active Power Unit (APU)?

The Active Power Unit (APU) is a technological innovation “Made in Germany” by TESVOLT. In the high voltage and 48 V TESVOLT storage systems, the APU serves as the interface between the battery modules and the inverter.

This system includes the following technological innovations:
  1. In order to isolate the battery from the charge controller, relays, which have a holding current, have been replaced by a static switch. The power dissipation of the static switch is calculated using the equation P=I2 * R. If no current is flowing, the static switch does not require any power – this increases the efficiency of the system.
  2. The rack, battery module and every individual cell is monitored.
  3. All battery modules are optimized via the individual Active Battery Optimizers on the battery modules.