Fascinating finding from Parliamentary Commissioner from the Environment Jan Wright that solar panels are not all they’re cracked up to be.
Turns out that if you’re putting solar panels on your home for water heating—their primary use—you’re doing to more to show your friends you’re “right on” than you are to reduce environmental costs.
The reason? In the New Zealand climate at least, most of the power load occurs in winter when solar water heating is less effective and back-up power is generated largely by coal and gas stations, whereas in the summer solar heating is more effective but far less useful—and any backup power needed is generated mostly by renewable hydro power.
RADIO NZ: Solar water panels are generally lauded by the green movement because they use the rays of the sun, rather than electricity or gas, to heat water.
But in a new report, the commissioner says solar panels do little to reduce the demand for new power stations or new transmission lines.
Jan Wright's report says solar panels work best in summer, or on sunny days, when renewable electricity is already plentiful.
They are less effective in winter, or on cloudy days, because the water they heat starts off colder and the rays of the sun are weaker.
That coincides with times when fossil fuel plants are used most and the environmental costs of electricity are greatest, but solar panels are least able to help out.
The report quotes figures showing solar panels use one kilowatt of back-up electricity a day in summer, and seven kilowatts of electricity a day in winter.
The most effective thing you can do to limit emissions and save yourself money, says Wright, is to install a ripple switch so your water can be heated with cheap off-peak power.
Not very sexy.
And if you have a pool, one which you’d like to warm up by a few degrees, I’d imagine solar tubing—simple back rubber tubing arrayed across your roof—would still be a good option.
Otherwise, it seems they’re not worth the candle.