Tonga's development partners discussed the Kingdom's future in renewable energy at a meeting last week, with biomass, wind and solar viewed as good options.
The Tongan government plans to lower its fossil fuel dependency for electricity generation from 100 to 50 percent in three years.
The kingdom's partners, including the Asian Development Bank and NZAid, presented an interim review of Tonga's energy sector in Vava'u last week.
NZAid's deputy director for Polynesian programmes, Guy Redding, says there's a big difference in cost.
"The first option is to look at a mixture of small scale solar demand side management and wind as well as biomass. They are talking about 35 million US dollars. And the higher cost option is to look at the larger solar plants, which will cost 100 million US dollars. But this would be over a lengthy period of time."
Guy Redding says more research is needed into wind generation.