## 4 Results and Discussion
### Financial Analysis Grid-Connected Photovoltaic Systems (On Grid-PV)  
It is important to note that the economic variables are generally accepted for the evaluation of investment projects; an evaluation period of 15 years was considered, where the results confirm the economic viability of the design, and these results are shown in Table 9. The financial results indicate that an investment of USD 30,062.61 is sufficient to obtain an average cost of 1.36 USD/Watt of the installed, proving that On Grid-PV systems for aquaculture farms offer attractive economic indicators. Figure 13: Photovoltaic system design target, 24% reduction in CO\({}_{2}\) eq emissions. The criteria for accepting or rejecting investment projects are as follows: NPV must be positive, IRR must be better than that offered by treasury certificates (CETES), for the Mexican case this is 6.52% [85], and BCR must always be higher than unity. When these three indicators are met, it is possible to consider the projects as viable [71; 72; 76]. Net Present Value (NPV) is the present value of future cash flows discounted at a given rate or discount rate. NPV measures the economic value of the investment as the sum of all discounted future net cash flows, all future cash inflows and outflows, and the investment cash flows are discounted in the base year using an appropriate discount rate and summed. When NPV \(>0\) (positive), the project will give a return in excess of the required discount rate and therefore the project is attractive to the investor; the higher the NPV, the more attractive the project [76]. The Net Present Value (NPV) obtained was MXN 911,723 (USD 41,517.44). The Internal Rate of Return (IRR) is the discount rate at which the NPV of the project equals zero; it is the sum of the discounted net cash inflows, equivalent to the sum of the net cash outflows over the life of the project [76]. In our case, the result was 33.8%. In the case of Mexico, there is a tax incentive of zero-income tax rate (ISR) for the promotion of investments in photovoltaic energy projects. The IRR is a convenient way to compare the profitability of projects with other types of investments, such as bonds and other financial investments, being a popular measure among managers and decision makers. The Benefit-Cost Ratio (BCR) is the ratio between the sum of the discounted net operating cash flow and the investment flow, and when the BCR \(>1\) it indicates that the project is feasible, since the net present value of benefits is greater than the costs. The higher the BCR value above 1, the more attractive the project [76]; the BCR of the distributed generation for aquaculture systems (DG-AQS) obtained was USD 5.6. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Financial Parameters** & **Unit** & **Amount** \\ \hline Inflation Rate & \% & 3.24 \\ Project duration & Years & 15 \\ Debt Ratio & \% & 70 \\ Debt Interest rate & \% & 8 \\ Debt duration & Years & 5 \\ Initial investment & USD & 30,062.61 \\ \hline Annual costs and debt payments & \\ \hline Annual costs & USD & \(-\)3664.96 \\ Debt payments/5 years & USD & 5269.17 \\ Total annual costs & USD & 1689.54 \\ \hline Annual savings and income & \\ \hline Annual savings & USD & 2738.79 \\ Income from greenhouse & USD & NA \\ gas reduction & & \\ \hline Financial viability & & Investment acceptance \\  & & criteria \\ \hline Internal Rate of Return IRR & \% & 33.8 & Higher yield obtained with \\ before taxes (capital) & & & CETES (6.68\%) \\ Internal Rate of Return IRR & \% & 13.5 & Higher yield obtained with \\ before taxes (assets) & & & CETES (6.68\%) \\ Return of capital & Year & 4.7 & Short investment payback \\  & & period \\ Capital repayment & Year & 5.1 & Short investment payback \\ Benefit–Cost Ratio (BCR) & USD & 5.6 & BCR \(>1\) \\ Net Present Value (NPV) & USD & 41,517.44 & NPV \(>0\) and positive \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Financial results of On Grid-PV systems for Nile Tilapia farm aquaculture. The capital investment is recovered in 4.7 years.