2 for the price of 1. The emergence of Agrivoltaics

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As the renewable energy juggernaut continues to roll out across Australia, a new model is emerging for solar farms. Agrivoltaics, or the European spelling, agrovoltaics, can best be described as dual use for suitable parcels of land, that being for solar power production and crop production. While these two distinct uses may seem incompatible at first, closer inspection reveals a viable alternative to traditional solar farm developments that, when broadly considered, can bring additional benefits to neighbouring communities that were otherwise off the table. I’ll discuss some of these benefits in more detail below.

First flagged and tested by Adolf Goetzberger and Armin Zastrow back in 1981, an agrivoltaic model falls into three categories. 1. Solar arrays with enough space between each for the growing of crops. 2. Solar arrays on stilts (up to 3 metres) that allow crops to grow underneath and 3. Greenhouse style where the solar panels are roof mounted onto a greenhouse building. Greg Barron Gafford has continued to carry the flame for dual use agrivoltaic solar projects by continually updating his findings from his research facility in Arizona.

Now knowing the large scale Australian solar landscape as I do, model number 1 is more than likely the only model we would ever see adopted in our wide, brown land. We do not have a shortage of space here in Oz so the second model is an unnecessary expense – unlike many European countries where arable land is scarcer than here. The greenhouse model has legs but for the sake of this column, I’ll focus on the first model.

Solar 101 tells us a solar farm is a series of panels in lines, tilted towards the sun. These panels produce shade and maintain cooler temperatures in the soil underneath, due to that shade. The space between panels is just that-space. With dirt. Both environments, therefore, present the possibility of plant and or crop production, thereby creating the dual use tag. Electricity and food. 2 for the price of 1.

Of the studies undertaken so far, and to be honest, they’ve not been carried out on massive solar farms, several benefits are emerging that may create secondary or Tier 2 income streams for communities nearby as well as mitigate heating issues around large scale solar arrays.

Firstly, Barron Gafford has coined the phrase PVHI or photo voltaic heat islanding, meaning just as what happens in cities, the cumulative effect of the sun hitting the solar array can increase the immediate ambient temperature above the farm – up to 4 degrees Celsius. In rural Australia, where 45 degree days are not uncommon, a few extra degrees is not on. Barron Gafford then suspected the lack of plant life under the arrays was exacerbating the PVHI effect. Sure enough, once plant life has been established under the panels, the subsequent temperature of a. the panels and b. the ambient temperature was markedly lower. In turn, the shading provided by the panels reduced evaporation in the crops and water consumption decreased.

So, for the horticultural entrepreneurs out there, these findings present some immediate opportunities. Naturally, crops such as wheat are not going to be any use, but what about say…corn between the arrays and cucumbers, lettuces or watermelons under the panels? Peas, beans and even herbs could work. Looking further afield, and outside of plants, could not a flock of high grade Merino sheep keep the grasses in check, saving on solar farm maintenance and be in a safe environment? Rounding them up would be a pain…

From my city bound, rurally ignorant perspective the benefits of a dual use, agrivoltaic solar farm are severalfold:

  • the potentiality of generating secondary income streams from otherwise unused land by growing and/or cultivating ‘boutique’ vegetable products (micro herbs, for example) can benefit local communities
  • the educational opportunities for school kids – go to the solar farm, sit under the panels and learn about renewable energy and veggie patches
  • the mitigation of heat islanding
  • the cooling of the panels for increased efficiency
  • THIS IS THE BIG ONE – Pollinators. Bees, butterflies, insects. It’s been said if we lose the bees, humanity runs out of food in 4 years. By dual using these solar farm sites we are regenerating otherwise derelict land, stripped of all vegetation, void of any of Nature’s natural checks and balances. By revitalising otherwise desolate landscapes that harbour only solar power generators (as important as they are) we are trying to correct the imbalance of industrialised farming practices inflicted on the land for decades. An agrivoltaic installed solar farm can help to redress this imbalance by giving bee, butterfly, insect and small fauna populations the chance to repopulate otherwise barren parcels of land. And that’s a good thing (apart from the stings…)

PowerVault Global has led the charge in Australia towards this new way of looking at things by factoring in the agrivoltaic model into its proposed solar farms in Mildura. These agrivoltaic farms are the first of their kind in Australia and should set a new benchmark in environmental, corporate and community responsibility. Each of the proposed farms will not only incorporate the planting of local floral species into its ground cover throughout each farm but also surround each farm with its own ‘vegetation fence’ – 4 metres high when fully developed that will run the perimeter of each farm. These initiatives will a) provide a natural fence around each farm to reduce the visual impact of the farm from street level. b) reduce the heat islanding effect. c) reduce the panels ambient temperatures for greater efficiencies. d) present otherwise unforeseen small business opportunities for local communities. e) provide educational opportunities and f) THE BIG ONE regenerate pollinator populations to the areas to be developed, returning bee, butterfly, insect and small fauna to the otherwise industrial landscapes, which in turn will benefit everybody in the long run – and it is a long run.

Smashing out solar farms because you can is one thing. Actually looking at the bigger picture, both environmentally and socially responsibly, is quite another. Depending on the particular circumstances incumbent with each unique solar farm project, the agrivoltaic model can offer communities extra bang for the buck, and we all love freebies.

Solar power is not going away, neither are the stresses associated with feeding a growing population. Both of these will feature large in the coming decades. As we transition to 100% renewables and address the issues with feeding 8 billion people, I’m of the opinion we will be seeing a lot more of the agrivoltaic modelling. Good. Very good. Simple idea, great results.

 

 

 

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