Field trial on Söderfjärden in summer 2021 show that sub-irrigation with a solar pump resulted in a 47% increase in yield.
In summer 2021, sub-irrigation with a solar-powered water pump was tested on Söderfjärden. The trial fields were divided into 3 different plots. One plot was left unirrigated, one plot was irrigated with a gasoline pump and the third plot was continuously irrigated for 48 days with a 17 m3 solar powered water pump. The results of the trials are shown below.
Crop: KWS Mistral spring wheat, sowing density: 670 plants/m2
Fertilization: 75 kg N/ha
| Irrigation | Harvest kg/ha | Additional yield kg/ha | Increase |
| Solar pump | 8 144 | 2 619 | 47 % |
| Petrol pump | 6 965 | 1 440 | 26 % |
| Unirrigated | 5 525 | 0 | 0 |
The results show that the additional yield was as much as 2,619 kg/ha with a solar-powered water pump. The harvest increase gives a net of 644 €/ha according to the wheat price in week 42 and the whole experimental field of 7.5 ha gave 4 832 € more in hand compared to the non-irrigated parcel.