Disgruntled solar electricity users/providers dominated the question and answer session at the end of Hawke's Bay Power Consumers' Trust's annual public meeting on Friday.
The trust owns Unison Group on behalf of its lines company's Napier and Hastings consumers.
Unison had a user-pays model of lines charges that was being increasingly undermined by the advent of home solar electricity.
In April, Unison introduced a higher tariff for solar electricity generators connected to its network.
It said home electricity generators paid about $300 less in lines charges than other customers annually but received the same level of service, typically using electricity during peak demand on cold winter nights when solar electricity was unavailable.
The increased tariff is for new installations. Existing solar customers remain on their current rate until March 2019.
Unison Group chief executive Ken Sutherland told the meeting the company had to invest to cater for "the coldest, darkest night" when solar generators used Unison's network, to which they were not contributing their fair share to its cost - the mainstream electricity supply was being subsidised by non-solar users.
Unison's general manager of business assurance Nathan Strong told Hawke's Bay Today there were 568 Unison consumers with solar generation in Hawke's Bay, Taupo and Rotorua and the assumption was they all availed themselves of the national grid on cold winter nights, despite battery technology.
He said the company was unaware of any customers with solar and batteries connected to the network, apart from those involved in a Unison solar-generation trial using batteries in Fitzroy Ave in Hastings.
"Batteries are only just coming into the market and, because they are so expensive, it is not currently economic for customers to install them with solar," he said.
"Over the longer term, when the prices come down, we think batteries will have significant potential to help reduce peak demands, so we'll be looking at ways in which prices can be set to encourage their deployment."
Unison declared a $9.683 million dividend for the year ended March 31, 2016, up from the previous year's $9.55 million dividend.
"The Unison Group achieved a strong performance during the year, both financially and operationally," Unison chairman Kevin Atkinson said.
Net profit after tax was $24.6 million, 10.5 per cent down on the previous years' profit. It was impacted by "unfavourable valuation movements on financial movements" linked to low interest rates. Operating earnings before interest and tax grew 4.1 per cent from $57.8 million to $60.2 million.
Mr Atkinson said last year's cold winter and increased commercial activity resulted in line revenue $2.8 million ahead of budget but this year's warm winter, to date, meant Unison was behind so far this year.