The two bidders for wind farm builder Tilt Renewables have struggled to convince investors to sell up.

Infratil and Mercury NZ — both Kiwi power operators — made the $2.30 cash bid in August.

Tilt’s (ASX:TLT) board shot it down as being inadequate — despite being a 31 per cent premium to the pre-bid share price.

But it’s been tough going.

The bidders already owned 77.8 per cent of Tilt and have only managed to convince a handful of shareholders that it’s worthwhile selling.

On Tuesday the bidders said they had 79.31 per cent.

An independent advisor valued Tilt at $2.56 to $3.01 a share.

Fiona Oliver, chair of Tilt’s Independent Directors Committee, has consistently said the Victoria government-backed Dundonnell wind farm as well as a pipeline of other projects meant the company’s potential was worth more than $2.30 a share.

Tilt is also a Kiwi company and dual listed on both exchanges. In New Zealand it was trading at $NZ2.31, while in Australia the stock has fallen back to $2.01.