The carbon intensity of the UK power system fell to a record low on 23 May, according to research by Drax Electric Insights.
Average carbon intensity reached 61 grams of carbon dioxide per kilowatt-hour (kWh), beating the previous record of 76g of CO2/kWh set on 17 August last year.
Drax Electric Insights said increased solar and wind power pushed the intensity level downwards.
At one point on Saturday, the lowest grid carbon moment was recorded at 33g of CO2/kWh, it added.
Drax Electric Insights said in a report in February that total UK power emissions had fallen by about two-thirds between 2019 and 2010 to 54 million tonnes from 161 million tonnes, as generators had shifted away from coal and natural gas to renewables.
Electric Insights is a series of reports commissioned by Drax and delivered by a team of independent academics from Imperial College London.