Canberra's first solar farm goes live south of Tuggeranong on Wednesday as construction is poised to begin on the second.
The second solar array will border the Monaro Highway and Mugga Lane, opposite Hume and adjacent to Rose Cottage on 49 hectares currently used for horse paddocks. Chinese firm Zhenfa is negotiating to buy the land from the ACT government.
The 13MW array will produce enough electricity to power 3250 households from 53,000 solar panels; fixed arrays at two metres high, and tracker arrays up to seven metres high.
It is set to be approved by planning authorities after changes to its bushfire plan – the government will not release details of the new requirements but a bushfire assessment with the company's development application points to a significant risk if vegetation around the array is not carefully managed.
The company has also done detailed work on whether glare from the solar panels will impact pilots on approach or take off from the airport, 10 kilometres away, and motorists on the adjacent highway.
The work suggests only one point at which pilots could be subject to glare – at 5000 feet on take-off to the south as they pass over the array.
The glare would come from the tracking array, which moves to track the sun, not the fixed array, and would only impact planes taking off to the south from the little used runway 17.
Planes taking off to the south about 4.30pm could pass through the zone of reflection at 5000 feet (1500 metres), but at a speed of 200 knots the duration of exposure would be only about six seconds. The view towards the array would be downwards at 25 degrees and between 60 and 120 degrees away from the direction of travel.
The glare time would be a few minutes after takeoff and even in the worst conceivable scenario where the pilot was so distracted that the plane lost directional stability there would be time to regain control, the report says.
It comments that pilots are routinely subjected to momentary glare from much larger surfaces, including Lake Burley Griffin.
It concludes that the likelihood of glare was remote, the consequences minor, and the overall risk negligible. The Civil Aviation Safety Authority confirmed it had no concerns about the solar farm.
The work also concludes that the risk to drivers is negligible, with drivers on the Monaro Highway and Mugga Lane only at risk of glare very late in the afternoon when the sun is low in the sky. But the chance of distraction is remote, the report concludes, with a much greater risk posed by direct glare from the sun itself.
The bushfire report rates a severe bushfire as possible in the area, with major consequences in a severe event. The last major bushfire in the area was in 1952 when a fire was pushed by a northwesterly wind. That possibility remained, as did a west or south-west-driven fire, which could impact on the Monaro Highway. The risk of fire impact in the Monaro Highway corridor was real, especially if the road verges were not maintained to reduce fuel loadings, it said, pointing also to the risk of ignition from cigarettes.
It recommended metal conduit for cables to prevent damage and arcing, fire retardant plantings and clear zones around the array, grassland kept to 10 centimetres under the array, as well as emergency access, and a fire-fighting water supply.
The Spanish Foreign Minister, Jose Manuel Garcia-Margallo, will attend the opening of the 83,000-panel Royalla solar farm off the Monaro Highway at Williamsdale on Wednesday, which is operated by Spanish company Fotowatio Renewable Ventures.