A Tongan organisation, the Women's Action Group for Change, says many families won't be able to pay more for their power bills.
This comes after Tonga Power put up charges by a further 23 percent to offset rising fuel costs.
Six months ago, the price of electricity was raised by 21 percent.
The organisation's spokesperson, Ofa Guttenbeil-Likiliki, says the price increase will be too steep for many Tongans.
"Our concerns are mainly the short period of time that the power has increased twice and the impact that this will have on women and families as other costs are going up as well. It's getting more and more expensive to transport children to school and to put food on the table. It's having a huge impact on many Tongan families."
Ofa Guttenbeil-Likiliki says the government should consider alternative energy generation to become less dependent on oil.