## 3 Results
### Feasibility Assessment
For the diesel-powered \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline  & & & & & & & & & & & & & & \\ \hline
**Crops** & **Area (ha)** & **Jan** & **Feb** & **Mar** & **Apr** & **May** & **Jun** & **Jul** & **Aug** & **Sep** & **Oct** & **Nov** & **Dec** \\ \hline Tomato & 0.5 & 10.1 & 22.1 & 29.9 & 12.1 & - & - & - & - & - & - & - & - & 7.2 \\ Tomato & 0.5 & - & - & - & - & 10.4 & 15.3 & 19.8 & 27.8 & 24.8 & 6.9 & - & - \\ Tomato & 0.5 & 19.8 & 4.8 & - & - & - & - & - & - & - & 13.4 & 20.6 & 26.2 \\ Total & 1.5 & 29.9 & 26.9 & 29.9 & 12.1 & 10.4 & 15.3 & 19.8 & 27.8 & 24.8 & 20.3 & 20.6 & 33.4 \\ \hline \hline \multicolumn{10}{c}{**Livestock water requirements (m\({}^{3}\) d\({}^{-1}\))**} \\ \hline \hline \multicolumn{10}{c}{Livestock heads} \\ \hline \hline \multicolumn{10}{c}{Cattle (adult, dry)} \\ \hline \hline \multicolumn{10}{c}{**Total water requirements (m\({}^{3}\) d\({}^{-1}\))**} \\ \hline \hline Total & 30.4 & 27.4 & 30.4 & 12.3 & 10.7 & 15.5 & 20.0 & 28.0 & 25.0 & 20.8 & 21.1 & 33.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Farm water requirements generated with the Water Requirements Tool of SPIS [50] showing daily water requirements for crop production, livestock and total for each month of the year. pumping system, the additional inputs were the fuel demand of the power generator, estimated to be 1 L/h, and the cost of fuel, assumed to be 18 ZAR/L. The financial feasibility performed with the Payback Tool indicated that the grid-powered system has the highest IRR, whereas the solar-powered system has the highest NPV and accumulated cash flow over 25 years (Table 3). The life cycle cost is the lowest for the solar-powered system, which will take 4 years to pay back compared to 3 years for the grid-powered system. With the current input data, the diesel-powered pumping system is not financially viable (Table 3). For diesel-powered pumping to be viable, the gross profit of the farm should be at least ZAR 390,000 per year. Likewise, if a proportion of the profit for payback is <20%, none of the systems would be feasible. Emissions of CO\({}_{2}\) will occur from the grid-powered system and especially from the diesel-powered system (Table 3). The cumulative income and system costs over 25 years are shown in the graph in Figure 3. The solar-powered system has the highest capital investment cost that is reflected in the first few years on the graph. The solar-powered capital investment is paid back after 4 years and, starting from year 7, the cumulative costs become lower than for the grid-powered system. From then on, the solar-powered system has the lowest cost throughout the lifespan of 25 years, amounting at >ZAR 400,000 lower cost than the grid-powered system at year 24. Fluctuations of the curves depend on the replacement value and life span of the various components. The cumulative costs of solar-powered systems increase sharply \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Financial Indicator** & **Solar-Powered** & **Grid Electricity** & **Diesel** \\ \hline Internal rate of return over 25 years & 25\% & 43\% & Not feasible \\ Net present value over 25 years (ZAR) & 4,063,542 & 2,962,363 & \(-\)2,870,302 \\ Accumulated cash flow after 25 years (ZAR) & 412,398 & 385,915 & \(-\)984,141 \\ System life cycle cost (25 years) (ZAR) & 1,422,232 & 1,448715 & 2,818,771 \\ Years to payback & 4 & 3 & No payback \\ CO\({}_{2}\) emissions per year (kg:a\({}^{-1}\)) & 0 & 956 & 3869 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Financial feasibility of three different groundwater pumping options calculated with the Payback Tool of SPIS [50]. Figure 3: Accumulated income and system costs for groundwater pumping using solar panels, grid electricity and diesel over 25 years generated with the Payback Tool of SPIS [50]. after 25 years, which is the time span of solar panels when these will have to be replaced. The cost of diesel-powered systems is by far the highest over-shooting the adjusted capital investment value from year 9 (Figure 3).