In work package 1, the action has investigated the control of modular converters with a PV panel connected to each module. It is shown that the converter is capable of Maximum Power Point Tracking (MPPT) on each PV panel without the need for any additional hardware such as a dc-dc converter which is typically used for MPPT. On the PV panel level, the Levelized Cost of Energy (LCOE) and energy yield are studied when the Lithium-ion battery is integrated. In the traditional system the need for an additional power converter for battery energy management results in increased LCOE. Despite high performance, it is seen that such a system may not be economical. Therefore, a solution with high efficiency and lower LCOE is desired despite higher capital expenditure.
In work package 2, the action has investigated innovative ways of integrating PV panel and battery pack such that the need for the additional dc-dc converter is eliminated. Such a solution not only results in high efficiency in the range of 99-99.6% but the reduced cost due to the elimination of dc-dc converters leads to a reduction in LCOE. The aim of doing so is to achieve a scalable, high-efficiency integrated PV-battery solution with decreased LCOE compared to traditional solutions in the market despite higher CAPEX. At the same time, it is observed that the performance of the battery is also enhanced due to the inherent pulsation current through the battery cells.
In work package 3, the action has studied the close interaction between the pulsating current through the battery due to the new configuration. It was initially thought that the pulsed current produced by the proposed solution would improve the battery charging performance. However, this was not found to be true. Through experiment, it was observed that the degradation of the lithium-ion battery in case of pulsed current charging was lower when compared to the traditional charging method (constant current - constant voltage. The proposed solution inherently generated pulsed current. The improvement in the lifetime of the battery was higher than 20% and for the specific case, a 50% higher cycle life was observed for NMC batteries. Such an extension in the lifetime of the battery will prove to benefit applications such as photovoltaic systems in bringing the LCOE lower than the current state-of-the-art systems with Lithium-ion battery storage.
