LITTLETON, Colorado, June 3 (Reuters) - Eastern Europe is often overlooked in discussions about solar power generation in Europe, where the likes of Germany and Spain dominate the growth in deployed solar electricity production.

But solar capacity across the nine largest solar producers in Eastern Europe has grown at over twice the pace of Europe as a whole over the past five years, and has helped Eastern Europe double its share of regional solar production since 2019.

At least six Eastern European nations will generate over 20% of their total monthly utility-supplied electricity from solar farms this summer, when regional solar radiation levels hit their annual peak.

In many of these countries, the rapid solar growth is displacing or curtailing output from coal and natural gas power plants, and is leading to a steeper fall in power sector emissions in Eastern Europe than across the overall continent.

Continued growth in solar capacity is expected across Eastern Europe over the medium term as nations there try to curb reliance on imported fossil fuels.

This in turn should further elevate the area's importance in driving Europe's broader energy transition momentum.

REGIONAL LEADERS

Nine nations across Eastern Europe are driving the region's solar expansion, according to data from energy think tank Ember.

In descending order of embedded utility-scale solar capacity at the end of 2024, those nations are: Poland (20.2 gigawatts of capacity); Hungary (7.7 GW); Romania (4.7 GW); Czech Republic (4.2 GW); Bulgaria (4 GW); Lithuania (2.6 GW); Estonia (1.3 GW); Slovakia (1 GW) and Latvia (0.5 GW).

Combined solar capacity of those countries was roughly 46 GW at the end of 2024, or roughly 13% of Europe's total 361 GW of solar capacity, data from think tank Ember shows.

That collective solar capacity footprint compares to just 9 GW in the same countries in 2019, and so represents a more than 450% jump in utility solar capacity in those countries in just the past five years.

Over the same period, solar capacity across Europe as a whole increased by a more modest 145%, and included an 89% rise in German solar capacity and a 246% climb in solar capacity in Spain.

OUTPUT IMPACT

The volume of utility-scale electricity production from solar farms has surged across Eastern Europe in response to the higher capacity footprint.

In 2019, total solar electricity output across the nine top solar producers in Eastern Europe was around 9 terawatt hours, but was nearly 42 TWh in 2024.

That nearly fivefold rise in Eastern European solar output contrasted with just over a doubling in solar output for Europe as a whole over the same period, from around 153 TWh to 361 TWh in 2024.

The share of solar power within Eastern Europe's combined electricity generation mix has also sharply climbed since 2019, and exceeds the solar share of electricity production within Europe overall.

Solar accounted for just 2% of Eastern Europe's electricity supplies in 2019, but topped 10% for the first time in 2024.

For Europe as a whole, solar accounted for a 7% share in 2024, up from a 3% share in 2019.

GROWTH MARKETS

Several Eastern European nations generated over 20% of total monthly electricity supplies from solar farms during the peak summer months of 2024, and are primed to generate even larger solar shares this summer following further capacity growth.

Lithuania, Hungary and Estonia all generated more than a third of their total monthly utility-supplied electricity from solar farms during June through August in 2024, Ember data shows.

Bulgaria, Latvia and Poland generated 20% or more of their electricity from solar farms.

This summer, following the build-out of further capacity across all of Europe, solar's share of the generation mix looks set to swell further - especially in Poland where installed capacity has grown by more than 25% since early 2024.

This expanded solar footprint will not only help push Poland's total solar electricity output to a new record this year, but will also serve to further reduce the country's overall power emissions.

Coal remains Poland's primary power source, but a near doubling in clean electricity output since 2019 - largely due to a nearly 2,000% rise in solar generation - has helped the country's utilities cut coal power output by 26% in that period.

Lower coal-fired generation has in turn cut Poland's power sector emissions from fossil fuel use by 23% or by 22 million metric tons of CO2 since 2019.

As Poland is Eastern Europe's largest polluter, the drop in the country's discharge has helped lower regional pollution, too, by 26% since 2019 to 163 million tons of CO2 in 2024.

This year, thanks to further increases in solar generation and additional cuts to coal power production, overall emissions across Eastern Europe could fall further and play a key role in advancing Europe-wide energy transition efforts.

The opinions expressed here are those of the author, a columnist for Reuters.