It is worth praising Qormi local council for implementing a solar lighting system for a monument and open space area (TMID, 30 May)

but I would also like to comment on some technical inaccuracies reported in this article. The statement that “The energy stored inside the solar panels will be used to illuminate the open spaces” is misleading.

Solar electric cells known as photovoltaic cells convert solar energy to electricity but unlike batteries, they cannot store electricity within. Any generated power that is not utilised immediately is automatically converted to heat. For the benefit of the readers, it is worth mentioning that there are mainly three types of solar electric systems, namely:

a. Stand-alone systems that could essentially consist of solar modules (panels) and, say, a dc-powered water pump. When the sun shines, water is automatically pumped into a reservoir for later use.

b. Stand-alone systems with battery storage, that is, solar modules are connected to rechargeable batteries via a control box. During the day, the batteries are charged and at night, the energy accumulated in the batteries is used to power the lights.

c. Grid-connected systems whereby solar modules are connected to an electronic inverter that interfaces with the electricity grid. In this case, the solar generated electricity is either consumed on site by electric appliances or fed back to the electricity grid. At the moment, Enemalta is offering a 2c/kWh rebate on any extra electricity units fed into its power lines.

For the said Qormi council project, it is important to stress the need for continuous monitoring and maintenance of the batteries. From experience, such systems need extra care especially due to the fact that they are operating outdoors. It is important to be vigilant so as not to fall into the same pitfalls experienced by previous systems installed in public spaces around Malta.

Charles Yousif

Secretary General

Malta Energy Efficiency and Renewable Energies Association