HOW TO

Basically the following components would be required:

1. PV (PotoVoltaic) panels to turn the sun energy to DC electricity
2. Grid-Tie Inverter to turn the DC electricity to AC electricity (240V 50Hz in Mauritius)

By wiring the PV panels to the grid-tie inverter and the grid-tie inverter to the Grid you are done, you are already feeding electricity to your utility company. Seems simple but you better be wise by knowing whats really happening and the workings of the grid-tie inverter. On the Utility side there is nothing to be done except for the meters which will allow it to pay back your electricity production.

An analogy to what is happening, is water running back in your mechanical water meter and decrementing the counter, except for here in case of malfunction there can only be water spillage which is not as harmful as with electricity there may be risks of electrocution, fire, injury and death.

The GRID-TIE Inverter

There are quite a few features which are mandatory in such a type of Inverter and are required to be compliant with the "Grid Code". The Grid-Tie inverter will synchronise itself to the grid electricity frequency and produce a current with a slightly higher voltage to push back the power to the grid.

1. Electricity generated should only be pure Sine Wave and never modified one.
2. Anti-Islanding: Only when electricity is present in the Grid that it will produce its output. In other words when there is a blackout in the Grid it will shut off automatically, this is a very important feature which prevents Utility personnel from getting electrocuted during maintenance.
3. Protection against: Overload, Short-Circuit, Lightning (using appropriate surge arrestors)

Depending on its design the inverter can require a battery bank or be battery-less, an important aspect to be taken into consideration as batteries are not that cheap and will also need a charge controller.

The PV PhotoVoltaic Panels

There are 3 types of PV panels available on the market with different efficiencies and price ranges. The efficiency is the amount of sunlight energy a panel can transform into electrical energy. On a surface area of 1 square metre there is around 1000W of sunlight energy reaching the earth surface, of course figure is for a clear sunny day at noon.

1. Monocrsytalline panels, efficiency 15~30%, most expensive,
2. PolyCrystalline or MultiCrystalline panels, efficiency 13~20%, having a speckle reflective appearance, and less expensive than MonoCrystalline panels.
3. Amorphous panels or thin film panels are the least efficient and least expensive. Compared to the above 2 types they are flexible.

PV panels are connected in arrays, which can be in parallel or series or even a combination of both, to obtain the desired voltage for operating the grid-tie inverters or charge controllers. The total output in terms of power will be the sum of the individual panels output.