In annual terms, the country's power output was up by 17%, the office of statistics said in a statement, citing provisional data.
The January output of the country's hydropower plants went down 10% monthly and grew 25% yearly to 438 GWh.
The output of the thermal power plants in Slovenia totalled 368 GWh in January, up 35% on the year and 23% month-on-month, while Slovenia's sole nuclear power plant, Krsko, produced 519 GWh of electricity last month, flat both on annual comparison basis and monthly.
In January, Slovenia imported 902 GWh of electricity and exported 974 GWh. Imports remained unchanged compared to the previous month, while exports decreased 7%.
On an annual comparison basis, imports declined 6% and exports went up 12%.
Nuclear energy had the largest share of 39% in Slovenia's total power production in January, followed by hydro energy with 36.6%, thermal with 22.6%, and solar and wind power with 1.8%.