Prepay customers could be paying as much as 17 per cent more for electricity, Consumer NZ research has found.

The watchdog compared the cost of prepay and pay-monthly power plans for a range of household scenarios on the Powerswitch price comparison site.

It found prepay customers could be paying significantly more for electricity, with those in Auckland and Wellington potentially paying 11 per cent and 15 per cent more, respectively, than their pay-monthly counterparts.

Price differences were even greater in Christchurch, where residents on prepay could be charged as much as 17 per cent more for their power.

On average, there were 15 cheaper power plans ahead of Globug, the single prepay option on the Powerswitch site, Consumer NZ campaigns manager, Jessica Walker​ says.

'Households on prepay pay more because they are excluded from the cost savings offered by other plans in the market, including the time-conditional plans which offer significant savings,” she says.

'It seems remarkably unfair that people already struggling to keep their lights on are forced to pay more for their power. Prepay customers pose no financial risk to their retailer.”

Prepay customers are automatically disconnected from their power supply every time they run out of credit.

However, there are no official records of how many households on prepay are going without power, as electricity retailers are not required to report those numbers, Walker says.

Based on statistics shared by a prepay power provider last year, Consumer NZ estimated about around 50 prepay households were without access to heat, light, hot water and cooking facilities every night.

Walker says there was a risk more households would switch to prepay as the cost of living crisis deepened.

Consumer's 2023 power company satisfaction survey found 6 per cent of households had switched to prepay because they had trouble paying their power bill.

In the same survey, 2 per cent of households reported their power supply was cut off in the last twelve months because they could not pay their bill.

'Our survey findings equate to around 40,000 households going without power at some point, because they could not afford it.

'We believe more investigation is needed so that regulators and policy makers have a clearer understanding of what's going on. No one should be shivering in the dark this winter, or ever, because they can't afford to pay their power bill.”

- Esther Taunton/Stuff.