The company said it was increasing its standard electricity tariff by 14.9% from 28 April but holding its gas prices for domestic customers.
SSE said the move equated to a 6.9% – or £73 – annual increase for a typical dual fuel customer.
The price rise will affect 2.8 million households in the UK unless they switch to a different tariff or provider.
Four of the other big six suppliers have already announced price rises this year, while British Gas has held prices until August.
- Scottish Power’s standard electricity prices will increase by an average of 10.8% and gas by 4.7% on 31 March.
- Npoweris raising its standard tariff electricity prices by 15% from 16 March, and gas prices by 4.8%
- EDF Energycut its gas prices by 5.2% in January, but its electricity prices rose by 8.4% on 1 March
- British Gasis freezing its gas and electricity prices until August
- E.On is increasing electricity prices by an average of 13.8%, and gas prices by 3.8%, on 26 April
While making its announcement, SSE said it was launching a £5m fund to provide “additional financial support for those who need it most.”
The managing director of its retail division, Will Morris, said: “We deeply regret having to raise electricity prices.
“This is the first increase since 2013 and we’ve worked hard to keep them down for as long as possible by cutting our own costs, putting in place a winter price freeze and holding gas prices, but we have seen significant increases in electricity costs which are outside our control.
“Without an increase we would have been supplying electricity to domestic customers at a loss.”
National fuel poverty charity Energy Action Scotland said having had a string of energy companies increase their prices recently, it was “almost inevitable” that others would follow.
Deputy director Elizabeth Gore added: “Many customers would have been fervently hoping that SSE would buck the trend and not announce price rises, however, the announcement today of electricity price increases of around 14.9 per cent will undoubtedly come as a shock, despite a hold on gas prices.
“For customers already struggling to afford basic bills such as energy, this price increase will have a real impact.
“Households reliant on electric heating will be particularly worried about the effect this price increase will have on their ability to afford to keep warm at home and to run basic appliances such as a washing machine and fridge.
“There needs to be more transparency in general about why energy prices rise and fall so that government and others can design policies that have least impact on those who can least afford it.
“Once again the volatilities of the energy market highlight the importance of having supports in place to assist the most vulnerable and these include cross-industry initiatives such as the Warm Home Discount. The news today that SSE will open a new £5 million fund to support customers who may be most affected by this price increase also welcome and will make a practical difference to these customers.
“We would always encourage customers to contact their supplier if they are experiencing difficulties with their energy bills. Customers should ask their energy supplier if they could make savings by moving to a different tariff or payment method. In addition, it’s worth shopping around to check the best deals available that suit customers’ own circumstances.”
Jamie Stewart, energy spokesman for the Consumer Futures Unit at Citizens Advice Scotland, said: “With many energy customers still struggling to make ends meet due to high fuel bills, today’s announcement is concerning. SSE is one of the largest suppliers in Scotland, with the majority of its customers on the more expensive standard variable tariff.
“Given the electricity price rise is substantially higher than that of gas, these increases will have the greatest impact on SSE’s customers who are not connected to the mains gas grid. This is particularly concerning as 16% of Scottish households are off-gas and fuel poverty rates are highest for households who use expensive electric heating.
“With many of the big suppliers increasing their standard variable tariffs it is essential that energy customers remember they are able to shop around to see who has the best deal on offer. The Citizens Advice Service independent online price comparison tool can help people work out how to save money on their energy bills.”