Analysis of charging capacity for electric vehicles in soviet-era apartment districts from the perspective of substation power availability

J. Lumi* and A. Tooming

Estonian University of Life Sciences, Institute on Forestry and Engineering,
Chair of Energy Application Engineering, F.R. Kreutzwaldi 1, EE51006 Tartu, Estonia
*Correspondence: janek.lumi@emu.ee

Abstract:

This article analyses the potential for electric vehicle (EV) home charging in a Soviet-era apartment district powered by the Lammi substation in Tartu, Estonia. Using one year of hourly electricity consumption data from 360 apartments, the study evaluates three load management scenarios to determine how many EVs can be supported without overloading the existing transformer infrastructure. The analysis is based on a worst-case winter week, reflecting realistic household consumption patterns and typical EV charging behaviour, which does not require daily charging. Three load control strategies are compared: (1) dynamic load management limited by weekly peak load; (2) fixed nighttime charging within a capped substation load; and (3) full dynamic charging for all apartments. The results show that up to 96, 218, and 360 EVs could be supported under these respective scenarios. The findings highlight how the choice of charging strategy significantly affects infrastructure demands and demonstrate that coordinated load management can enable broader EV integration without immediate large-scale investment. The study contributes practical insight for energy planners and housing associations seeking to align smart charging systems with the technical limits of existing substations.

Key words:

charging, electric vehicles, load management, residential charging, substation capacity

Analysis of the power balance of a solar catamaran

D. Berjoza¹*, I. Jurgena²* and A. Einstals¹

¹Latvia University of Life Sciences and Technologies, Faculty of Engineering,
Motor Vehicle Institute, J. Cakstes blvd 5, LV3001 Jelgava, Latvia
²Latvia University of Life Sciences and Technologies, Faculty of Economics and
Social Development, Institute of Business and Management Science, Svetes street 18, LV3001 Jelgava, Latvia
*Correspondence: dainis.berjoza@llu.lv; inara.jurgena@llu.lv

Abstract:

Significant changes are expected in the percentage distribution of vehicles in the world over the next decade. It is planned to gradually replace conventional internal combustion vehicles with electric drive ones, thereby reducing environment impacts and the production of gases contributing to the greenhouse effect. It is necessary to foster similar trends regarding watercraft, replacing the internal combustion engines with electric motors. An experiment used a solar-powered catamaran equipped with a standard electric motor Minn Kota Endura 34, a 450 W monocrystalline solar cell and a 40 Ah lithium iron 12 V battery. A pyranometer was used to measure solar energy. The experiment used a data logger GL 220 that measured the energy flow to the battery and the electric motor. The experiment was conducted in Jelgava on 5 July 2022, with the maximum altitude of the sun reaching 56.7°. The experiment identified that at an average solar intensity of 500 W m^-2 on a sunny day, the solar catamaran could be moved by means of solar energy without discharging the batteries at all power settings.

Key words: