## Lesson 21. Performance evaluation of solar street light systems

Nowadays, installation of solar street lights becomes common in remote as well as urban areas.  The evaluation of performance of the solar pumping system can be carried out based on the solar insolation as input and power consumption of street lights as output.

The required data are

• Average solar insolation, W m-2

• Average sun shine hours in the test day, h

• Area of one SPV module, m2

• Number of SPV modules

• Wattage of street light system, W

• Operating factor = 0.7 (considering the peak rated power of PV panel

Problem

A solar street light has two SPV panels of 37 Wp capacity.  Considering the peak rated power of the panel the operational factor of the panel is decided as 0.65 (including mismatch factor).  The average solar radiation in the experimental area is observed as 580 Wm-2 and the average sun shine period is 8 h.  The area of one module is 65.5 X 61 cm.  A 12 V battery of 75 Ah with C/10 discharge rate is used for storage purpose.  The light is fitted with 11 W CFL.  Assess the efficiency of the system.