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Solar expert says heat might not spread

By Country News

A solar energy expert has told a planning panel that solar farms could generate a heat island effect but the heat may be dissipated beyond the boundary of the properties.

The potential for solar arrays to generate heat has been a sticking point for farmers objecting to the location of solar farms in the Goulburn Valley.

Some farmers believe the heat generated by the solar farms could have a negative effect on budding of fruit trees, which require a certain number of chill hours during winter.

Greater Shepparton City Council commissioned engineer Ken Guthrie to complete a report on the heat island effect and other impacts of solar farms.

‘‘Any impact of heat that may build up during daylight hours can be mitigated by facilitating overnight radiative cooling of the ground by turning the PV (photovoltaic) array to maximum tilt overnight so that heat can be radiated to the cold night sky from the warmer ground,’’ Mr Guthrie said in his report.

‘‘A vegetation buffer may assist with cooling of the solar farm due to transpiration, however, it may also reduce cooling winds across the panels during the day.

‘‘On balance, the impact on heat build-up within the array will vary from a tendency to increase or decrease depending on the particular conditions at a particular time.

‘‘However, a vegetation buffer will reduce impacts of radiation to the surrounding area in all conditions.

‘‘Whilst decreasing heat build-up will be important to the operator of the solar farm, as PV output reduces as temperature of the panels increase, for neighbours the major issue will be to reduce the potential for heat transmission out of the solar farm into neighbouring properties.

‘‘An effective strategy to mitigate heat transmission out of the solar farm is to provide a buffer of dense vegetation surrounding the solar farm.

‘‘The vegetation should be visually dense from the ground to higher than the top of the PV array at its highest point.

‘‘In my opinion a dense vegetation buffer will effectively stop heat transmission to neighbouring properties.

‘‘There will be minimal effect on temperatures more than 100m from the outside of the vegetation.’’

Mr Guthrie found summer-time temperatures could be 0.1°C to 4°C higher above the panels.

In the soil under the PV panels, temperatures are cooler during the day and warmer at night, than outside the PV field. PV installations shade a portion of the ground and therefore reduce heat absorption in surface soils.

Mr Guthrie said tracking collectors intercepted more solar irradiance than fixed arrays, and therefore provided shade to the ground under the array.