| Pgen | Generator power |
| Ppanel | Power of available panel on the market |
| Psh | Number of peak sunshine hours per day |
| PWP | Permanent Weitling Point |
| Q | Flow rate |
| Qe | Emitters flow rate |
| r | Interest rate |
| Re | Reynolds number |
| Rn | Net radiation |
| SAT | Saturation |
| T | Mean daily air temperature |
| TAW | Total Available Water |
| u2 | Wind speed measured at 2 m height |
| γ | Psychometric constant |
| Δ | Slope of the saturated vapor pressure curve |
| ΔZ | Difference in elevation between the water source and the most unfavorable supply inlet |