Grain Aeration with Photovoltaic Solar Energy (and 3)

Silo à grain peint

Grain Silo (Wikipedia)

How to aerate GRAIN with SOLAR energy?

In this last post # 3 of this series, I’d like to share with you some ideas about solar PV to ventilate cereals

(See post # 1 and post # 2 of this series for further understanding).

DRYING Process.

If you have opted for a small investment (fans of 0.1 to 0.2 m3, min, ton of grain), it is not enough to really dry, as it requires 10 times more power (and investment!). But something will!

- Enter the grain inside the silo reasonably dried (<20% moisture). If you enter it very moist, the small fans will no be able to really dry out and your grain will rot.

- Make operate the small fans only during the day, when shine. At night, nothing at all. The long summer days help to ventilate many hours a day.

- In summer season you can enter the ambient air in the silo, which will likely be warmer than inside. This will help to finish drying, to a moisture content <15 ° C.

- Be careful not to maintain high humidity together with high temperature for more than two or three months, or you will lose the whole crop!

According to this chart, in the weeks of summer days, the outside temperatures will be high, which will contribute to raise the temperature of the grain and so, dry slowly.


When the objective of low moisture is achieved, you should change to cool mode.

You need two temperature sensors: one for indoor air and the other for outdoor air. When the outside temperature is 5 ° less than the inside, fans will be implemented, if there is sun. Conversely, if the outside temperature is higher than the interior, not be put in place to avoid overheating the grain. Since it is moving progressively towards winter, there will be many times when it may inject cold air. But again, only by day when sun.

Whatever the internal temperature is, if you inject air when it is at least 5° below, it will cool the grain every week. For example 77ºF outside and 66ºF inside  take about 73ºF inside after a while. If you are already at 72°F internal and blow 61°F external, you should get about 68°F. So on, day by day throughout all autumn and winter you will get at the end indoor temperatures below 60ºF, ideal for the preservation of long-term grain without fungi or insects.

This option would be ideal cooling it during fresh overnight, but then it would require an expensive battery system, hardly profitable for this function and decreasing the overall performance.

The collaboration between the local agronomist expert, the specialist in ventilation of silos and the photovoltaic energy professional can help you properly size your local case.

Use Photovoltaic System for the entire Farm

If you think the investment in photovoltaic modules to ventilate only a grain silo is too high, you can get a broader approach:

Use the installed capacity to ventilate the silo directly and also, with battery support,  for electric power needs of YOUR off-grid home or farm. There are many possibilities to make a profitable solar PV investment in your farm isolated from the mains.

We are very much interested in your opinions!

1 comment
  1. Donald said:

    Many thanks for taking some time in order to compose “Grain Aeration with Photovoltaic Solar Energy
    (and 3) | Rural Renewable Energies for Farmers”.
    Thank you so much once again ,Elsie

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