## 3 Results
### Cost per Litre of Water Produced  
It is possible to estimate the cost per litre or the cost of generating a litre of water with the maximum and minimum values of water harvested. As is well known, for the case studies photovoltaic panels were used as the AWG power source; in order to estimate the cost we will consider electrical power to have been supplied by the local power company, CFE, at the corresponding rate (1A). Rates for the Matehuala region have three levels: Basic (is the first 150 kWh of usage, charged at a rate of 0.062 USD), intermediate (the following 150 kWh of usage after the basic rate, charged at a rate of 0.077 USD) and surplus (any usage exceeding the intermediate rate, charged at a rate of 0.221 USD per kWh).  
To calculate the cost per litre of water produced by the AWG, the following equation was used:  
\[\text{USD}/\text{litre}=\frac{(\text{Watts produced})(\$\,\text{per KWh})}{\text{Litres of water produced}} \tag{14}\]  
For this analysis, the maximum and minimum amounts of water harvested during the months of the year (January and February) were taken into account and the cost of water production in the region was estimated using the different refrigeration packages. Results are shown in Figure 10.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Month**} & \multicolumn{4}{c}{**Water Harvested with 1/4 Ton of Refrigeration (Litres)**} \\ \cline{2-7}  & \multicolumn{2}{c}{**25\% Reduction**} & \multicolumn{2}{c}{**50\% Reduction**} & \multicolumn{2}{c}{**75\% Reduction**} \\ \cline{2-7}  & **Max** & **Min** & **Max** & **Min** & **Max** & **Min** \\ \hline January & 1.35 & 0.89 & 1.79 & 1.24 & 2.54 & 1.87 \\ February & 1.61 & 1.06 & 2.14 & 1.49 & 3.05 & 2.24 \\ March & 2.02 & 1.33 & 2.69 & 1.87 & 3.82 & 2.81 \\ April & 2.31 & 1.52 & 3.06 & 2.13 & 4.35 & 3.20 \\ May & 2.35 & 1.55 & 3.12 & 2.17 & 4.44 & 3.27 \\ June & 2.38 & 1.57 & 3.15 & 2.20 & 4.48 & 3.30 \\ July & 2.25 & 1.48 & 2.98 & 2.08 & 4.24 & 3.12 \\ August & 2.41 & 1.59 & 3.20 & 2.23 & 4.54 & 3.34 \\ September & 2.07 & 1.36 & 2.75 & 1.91 & 3.90 & 2.87 \\ October & 2.03 & 1.34 & 2.70 & 1.88 & 3.84 & 2.83 \\ November & 1.56 & 1.03 & 2.08 & 1.45 & 2.95 & 2.17 \\ December & 1.37 & 0.90 & 1.82 & 1.27 & 2.58 & 1.90 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Maximum and minimum amounts of water harvested in the months of the year with a compressor with \(\frac{1}{4}\) ton of refrigeration capacity.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Month**} & \multicolumn{4}{c}{**Water Harvested with 1/2 Ton of Refrigeration (Litres)**} \\ \cline{2-7}  & \multicolumn{2}{c}{**25\% Reduction**} & \multicolumn{2}{c}{**50\% Reduction**} & \multicolumn{2}{c}{**75\% Reduction**} \\ \cline{2-7}  & **Max** & **Min** & **Max** & **Min** & **Max** & **Min** \\ \hline January & 2.7 & 1.78 & 3.58 & 2.49 & 5.09 & 3.74 \\ February & 3.23 & 2.13 & 4.29 & 2.99 & 6.10 & 4.49 \\ March &  
The results show that the cost per litre of water was very low, even when an average consumption was maintained (average rate), in a range of $ 0.0093 and $ 0.038 USD/L of water harvested by the AWG. The costs obtained per litre harvested were affordable to any type of population that lacks water services.