Battery system for dynamic electricity tariffs only: 1Komma5° PowerHarvester

The solar company 1Komma5° is presenting a battery system designed for households without a solar system, the "PowerHarvester". The battery will cost at least 8900 euros for the smallest battery size of 7.7 kWh, including the "Heartbeat AI" energy manager, a smart meter and all installation costs. According to the provider, this price should pay for itself in just six years for households with consumption of over 10,000 kWh per year. The battery is therefore particularly suitable for households with electric cars and heat pumps. The PowerHarvester is available in the sizes 7.7 kWh, 11.6 kWh, 15.5 kWh, 19.4 kWh, 23.3 kWh and 27.2 kWh.

In addition to the hardware, customers need a dynamic electricity tariff and a subscription to the "Energy Trader", which calculates the charging/discharging forecasts on the server side. It costs 9.90 euros per month. The system is AC-coupled, i.e. equipped with its own battery inverter. This allows extensive compatibility with the rest of the home's electrical system.

The maximum efficiency of the silicon carbide inverter is 98.2 percent. This occurs when charging the battery from the mains. The Heartbeat device incorporates the lower efficiencies of the lower partial load range (i.e. mainly house base load) into the battery schedule. 1Komma5° has not yet provided any information on the rated power.

Households help the energy market

"At the moment, Germany regularly gives away surplus clean electricity from wind and solar power abroad. We then later buy electricity back at high prices when solar and wind are not available. This is economic madness," says Philipp Schröder, CEO and co-founder of 1Komma5°. "With the PowerHarvester battery, we are now enabling all electricity customers to benefit directly from these electricity volumes and become part of the permanent solution to this problem."

Agora Energiewende also firmly believes that private households will buy the expensive storage systems because commercial investors will only do so if the return on investment is right. However, households should also calculate whether they are at least reasonably well served economically.

As of April 14, 2025, the average German electricity costs are 27 ct/kWh. If, for the sake of simplicity, we calculate with 30 cents and the promised maximum reduction by half, the PowerHarvester has an average spread of 15 cents. Not including losses, even in an ideal scenario it would have to pump through almost 60,000 kWh to amortize the minimum price of 8900 euros.

The average charge-discharge efficiency ("round-trip" efficiency) of inverters is between 75 and 85 percent (due to the partial load component). The Energy Trader costs 118.80 euros per year. Including average losses and a six-year software subscription, the battery would have to process over 80,000 kWh in six years to pay for itself. For the 7.7 kWh battery estimated here, this means well over 10,000 full cycles just to reach zero return.

(cgl)