Ways to avoid sun, and capture it

On average, New Zealand receives around 2000 hours of bright sunshine a year, providing a solar energy resource of about four kilowatt hours per square metre per day. Photo / Thinkstock

Sophisticated apps from Niwa forecast UV dangers and show the amount of solar energy available for power.

Real-time technology developed by Niwa reveals when we should avoid the worst of the sun and harness the best of it this summer.

Tools on the National Institute of Water and Atmospheric Research's site can be used to gauge UV index forecasts, available for nearly 40 centres around the country, or show the amount of solar energy your home receives.

A check on Niwa's UVI forecaster shows in most centres UV reaches "extreme" levels between noon and 3pm, although it is often high enough to warrant sun protection as early as 9am and as late as 6pm.

Levels are considered extreme when they pass 10 on the UV index.

In a typical summer, levels reach maximums of 12 on the index but could exceed 13 in areas in the far north.

More in-depth analysis can be found in Niwa's UV atlas, which has hourly temperature, sea level pressure, measured broadband radiation and humidity data from the National Climate Database.

Solar View, another application, allows homeowners using solar power to check the amount of energy available where they live.

The technology can depict the sun's path from sunrise to sunset - even factoring in local terrain.

Niwa's system draws on Google Maps to find latitude and longitude based on the address of a home, and then combines topographical data and many years of climate data from climate stations to give a month-by-month calculation of solar energy.

"One of the great things you can do with Solar View is ask the information for a panel of any tilt and bearing," said Solar View creator and Niwa scientist Dr Ben Liley. "You can look at how much solar energy you get from a vertical wall, from a west-facing wall or on a flat surface."

There had been an uptake in solar water heating systems, while there was now a "big focus" among homeowners from direct electricity production from panels, Dr Liley said.

On average, New Zealand received around 2000 hours of bright sunshine a year, providing a solar energy resource of about four kilowatt hours per square metre per day.

Many homes were exposed to 20 to 30 times more energy from the sun annually than they used in electricity or gas - and if all Kiwis harnessed a three-kilowatt solar panel array, they could collectively generate enough power in a year to satisfy more than a quarter of annual residential electricity needs.

Other features available through Niwa include a tide forecaster, predicting high and low tide times and heights for all open coastal and ocean waters for up to 28 days ahead, and Cam-Era, providing hourly or half-hourly screen shots from cameras mounted at Tairua, Pauanui, Raglan, Ashburton and New Brighton.

While scientists use the resource for gauging beach processes, the cameras can be used by fishermen, surfers and people who just want to go for a swim.

Get smart

Daily UV forecasts: tinyurl.com/bqr5cb7

UV atlas: tinyurl.com/c7t2q9e

Solar view: tinyurl.com/cokow9a

Tide forecaster: tinyurl.com/d7z49c4

Cam-era: tinyurl.com/chmhhnn