Four major changes are needed to fix New Zealand's electricity market, Consumer NZ says.It has released a new report, which outlines what it says a four main drivers of high power bills, and suggests four solutions.It said household power bills had risen at nearly twice the rate of wider inflation since the electricity market was reformed 27 years ago, and households were suffering. More than 30,000 had their power disconnected at least once in the past financial year because they could not pay their bills."We've been concerned for some time that the electricity sector is not showing up well for consumers … it's doing great things for gentailers, it's doing good things for dividends paid to the government and other shareholders, but increasing numbers of New Zealanders are struggling to pay their power bill," chief executive Jon Duffy said."I think there's more than 60 reports that have been written on the electricity sector over the last couple of decades, and none of them was actually written from a consumer's perspective, so we wanted to put something out there that sent the message, particularly in election year, to the government to say something needs to be done to change how the sector's treating consumers."The report said the big power companies were too dominant in the market. "Contact, Genesis, Mercury and Meridian control most of the retail market and own substantial generation assets, giving them advantages that smaller independent retailers and generators do not have."It said power prices did not reflect real costs, there had not been enough investment in homegrown energy and politics had got in the way of having a long-term plan.To tackle that, Consumer said the dominance of the gentailers needed to be reduced, power prices should better reflect the cost of generation, there should be more investment in local power sources so that New Zealand was not reliant on coal and gas, and there should be a cross-party energy strategy to put affordability, security and emissions reductions first.Duffy said he was not suggesting the gentailers had to be broken up, but there needed to be more competition. "It's really difficult for a new entrant to come into the retail part of the market knowing they have to buy power off the very companies they're competing with. Something needs to be done to shift that imbalance of power."Secondly, we have a system that prices electricity at the cost of the most expensive fuel."So if 95 percent of our generation on a given day is generated by hydro, wind, and solar, which is free fuel, but 5 percent is generated by burning gas and coal, [that drives] the price for all of the electricity generated that day. We don't think that market model, which was actually designed more for European jurisdictions where there's a much lower percentage of renewables, is right for a really highly renewable grid like we have."He said gentailers were now investing more in generation because of the growing demand from data centres."That's cold comfort for the 25 percent of New Zealand households struggling with their power bill."Duffy said it was a hard issue for politicians to tackle."They call it the trilemma in the electricity sector where you've got to balance security of supply, so keeping the lights on, with sustainability, we want to reduce emissions generated by electricity generation, and affordability. You have those three factors, all of which have high importance, but security of supply tends to trump all of them, and I guess if you're a Minister of Energy sitting there, and a gentailer turns up and says, 'well, if you make these changes to the market, we won't be able to supply power, and you're going to have people who vote for you sitting in the dark not able to heat their homes, because we can't get power to them', that scares you into what has actually been over multiple terms of government, basic inaction."He said it was disappointing that no political parties had released comprehensive policies covering the whole energy system."That's why we need a strategy. The challenge for political parties is to go back to the drawing board, do some more thinking, come up with some decent policy to help people out of the situation that politicians have allowed to evolve."Sign up for Money with Susan Edmunds, a weekly newsletter covering all the things that affect how we make and spend money.