By Jan TenBruggencate
Advertiser Columnist

Solar photovoltaics are a technology that some mainstream power folks have loved to hate.

There are lots of reasons to ignore it. It's expensive. It doesn't produce power unless the sun's shining. It takes up a lot of space for the amount of electricity produced. All those things.

But little by little, applications have appeared for which solar seemed made-to-order.

Cabins in the hills, where a few lights and perhaps a radio were all that was required seemed perfect for solar panels.

They showed up on satellites, where access to sunshine was easier, and fuel trucks were in short supply.

They appeared on top of poles to power Hawai'i's tsunami warning sirens, where you'd want electricity even if local utility lines were down.

Remote communications stations no longer needed generators that required regular fueling and maintenance. Most solar systems last years, and need maintenance only when batteries wear out.

Light fixtures out in the country. Emergency telephones far from the nearest power source. Trickle power sources to keep a car battery charged when parked for long periods, and to keep boat batteries topped off.

Basically, anywhere you couldn't readily fuel, or couldn't readily run a power line, if the power needs were not too large, solar photovoltaics made sense.

Now a group of researchers has developed a new application. It's a combination of satellite and remote communications antenna technology.

The Pathfinder-Plus is a solar-powered aircraft that has been tested this summer in the skies over Kaua'i, flying from the runway at the Pacific Missile Range Facility.

It builds on previous solar plane models, but this one carries an interesting cargo.

The remotely controlled plane carries communications gear that lets it relay cell phone signals and send out television and even Internet transmissions.

Aircraft builder AeroVironment, the Japanese Ministry of Communications and NASA flew the plane three times over Kaua'i and proved that the communications technology can work. AeroVironment is working on battery and solar panel technology that will allow the plane to store enough power during the day to keep the plane aloft all night.

The successor to Pathfinder-Plus would essentially become a permanently flying plane — one that never needs refueling. It's not a cheap plane, but it ends up being substantially more financially efficient than sending up satellites.

The goal is to have a plane that can stay aloft for up to six months at a time, as an all-purpose regional communications platform whose signals aren't affected by the roll of the terrain.

Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. You can call him at (808) 245-3074 or e-mail jant@honoluluadvertiser.com.