Switching dual fuel provider every year saves the average consumer more than €1,400 over four years, according to the Commission for Regulation of Utilities.
The CRU's Energy Retail Markets annual report for 2017 shows there are now 12 suppliers active in the electricity market, up from five in 2013.
There are now eight suppliers active in the gas market, up from four in 2013.
It also noted that for the first time Electric Ireland has seen its market share fall below 50% for the first time with the company now holding 49.5% of the energy market.
Bord Gáis Energy kept the second biggest market share by consumption in the electricity market with 17.8% followed by SSE Airtricity with 15.36%. The remaining key suppliers are Energia with 7.9%, PrePayPower with 5.9%, Panda with 1.5% and Pinergy with 1.4%.
Bord Gáis Energy held the greatest market share in the domestic gas market with 47.2% of the market by customer numbers. This was followed by Electric Ireland with 21.3%, SSE Airtricity with 14.2%, Energia with 7% and Flogas with 5.6%.
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The CRU said the customer switching rates in the electricity and gas markets stood at 14% and 18% last year respectively.
Another 8% of customers in both markets re-negotiated with their current supplier in 2017.
It said that customers who switched or renegotiated every year for the last four years could have saved €670 on gas, €1,146 on electricity or €1,417 on their dual fuel costs.
The CRU also said that the end of 2017 saw a significant increase in both wholesale electricity and gas prices, although these increases were still lower on average than 2014 and 2015.
Six energy companies have increased their prices for domestic customers in recent days, while Bord Gáis said today it was also hiking its gas and electricity prices from next month.
The Commissioner with responsibility for the Retail Markets, Aoife MacEvilly said that the continued downward trend of market share of the largest supplier is a good indication that competition has continued to grow.
"While the recent price rises announced by suppliers will have an impact on customer bills, the data from this report shows that active consumers who either switch or renegotiate with their supplier could more than beat the recent price rises and still see a significant saving," Aoife MacEvilly said.
"Prices change regularly and the CRU encourages customers to shop around for the best deals every year," she added.