»Energy Storage Inspection« first tests two independently purchased systems – with poor results

As part of their »Perform« research project, the Karlsruhe Institute of Technology (KIT) and the Solar Storage Systems Research Group of the Berlin University of Applied Sciences (HTW) have placed two solar power storage systems on the KIT test stand and evaluated them according to the criteria of the »Energy Storage Inspection« (Stromspeicher-Inspektion). This annual test series, the results of which KIT and HTW last published in February of this year, has so far been based only on voluntary participation by manufacturers, some of whom do not allow their products to be named. For the two tests now carried out, however, »two frequently installed solar power storage systems were acquired and examined more closely«. Nevertheless, KIT and HTW refrain from naming them here as well.
The test field of 18 devices from the last Energy Storage Inspection thus expands to 20, and the two newcomers – both 10-kilowatt systems with hybrid inverters and lithium-ion storage – occupy 16th and 20th place in this classification sorted by overall energy efficiency. The reasons for the poor performance are »manifold,« according to a statement from the HTW. However, the very low conversion efficiency of 84 percent at low utilization is highlighted for one of the two systems; the most efficient systems are ten percentage points higher at the same utilization. The second system showed indisputable values with 64 watts standby consumption and a »settling time« (the time span for adapting to new performance values) of almost eleven seconds; very good systems are at 2 watts and less than 0.2 seconds, respectively, here.
The results for the two newly tested systems are also integrated into the online tool of the Energy Storage Inspection, which can be used to compare important properties of the systems with each other.
© PHOTON