*3.2. Evaluation of Power Losses for two shaded panels*

The previously obtained performances only consider a shaded panel, and the logic is to maintain it (partially shaded) or exclude it (totally obscured). Now if two panels are shaded there is the possibility of placing in parallel. Panels named 6 and 7, can be re-configured to ensure the maximum current of the arrays. This feature requires a more evolved DRS, which can put in parallel panels belonging to different arrays, the sum of which currents is equal to the current of not obscured panels. This feature is useful only when it considers case 2 as shown in Table 13. The performances of different DRS are a mixture of the ones presented in Tables 12 and 13. For the economic analysis the increased power given by the reconfigurator is taken as an increase of the energy produced during the day.


**Table 13.** Electrical characteristic of the string in different shadow conditions.

#### **4. Economic Data**

In order to carry out a complete study, the economic analysis presented in this paper takes into account different aspects of a PV plant, such as PV technology, location of the installation, government incentives, component lifetime, aging and periodic maintenance costs.

This study is based on the use of economic a tool called net present value (NPV), in order to evaluate the benefits of an economic investment in PV field with innovative devices such as a DRS. The NPV allows to evaluate the economic convenience of an investment for a specific period from a sum of cash flows actualized at time zero. In (6) the mathematic expression to evaluate the NPV is reported:

$$\text{NPV} = -\mathcal{C}\_0 + \sum\_{y=1}^{n} \frac{\mathcal{C}\_y}{(1+i)^y} \tag{6}$$

With reference to expression (6), *C*<sup>0</sup> is the cash flow at time zero, *Cy* is the cash flow at the year *y*, *i* is the interest rate and *y* is the year of investment. Thus, the sign of the NPV, positive or negative, indicates the infeasibility of the investment and therefore the economic convenience. The interest rate *i*% considered in this work is equal to 5%. In this study, the technical-economic analysis has been carried out by considering an investment time equal to 20 years. In the following, detailed description of different aspects taken into account for the economic analysis and economic data are reported.
