Forsyth Barr's Harvey-Green said the reduced demand was more pronounced on the east coast of the South Island, and to a lesser extent in the North Island, with Auckland's expanding population underpinning demand in the country's biggest city.
"It's hard to see what's going to turn it around. It tends to be the big things that move demand in a big way, either up or down," he said.
The latest operating reports show generation across the four companies was up 2.5 per cent to 18,219 GWh, due largely to a 7.5 per cent increase in Meridian's generation to 7,029 GWh, reflecting ample water supplies in hydro storage lakes. Genesis's total generation shrank 7.9 per cent to 3,110 GWh in the half as coal-fired generation was scaled back almost completely, while Contact generation dropped 7.7 per cent to 4,310 GWh on lower thermal and geothermal generation. Mercury's generation dipped 0.2 per cent to 2,367 GWh.
In a note, Morningstar analysts said Mercury had a "fairly soft" December quarter with energy margins down on the prior period and was tracking slightly below the firm's forecasts, with the lower sales price "a key detractor from earnings" reflecting "additional commercial and industrial sales re-contracting at lower prices than achieved historically". It retained its $3.10 share price target and 'hold' recommendation on the stock, which recently traded unchanged at $3.08.
In a separate note, Morningstar said Meridian's first-half energy margin would only be slightly higher than a year earlier due to a soft December quarter, although increased storage levels in hydro-dams put it in "a good position to maximise hydroelectric output in the near term" even it did weigh on wholesale prices. Morningstar was also upbeat about Meridian's Powershop Australia retail brand, which it said was performing well. The research house also kept its price target at $2.72 and 'hold' recommendation for Meridian, which recently traded at $2.75, unchanged on the day.
Genesis shares slipped 0.2 per cent to $2.155.