PV Panels or modules are undoubtedly among the best suited sustainable energy devices for your home power needs. There are many different types of PV Panels who differ chemically as well as physically. Further the mode of operation too differs in several others. Inspite of all these developments, the most popular and still the best compromise for economy and performance for your home seems to be the Mono crystalline silicon modules, closely followed by Poly (or Multi) crystalline and Ribbon Silicon modules.

The first named is the one with the highest efficiency but is the most expensive out of the lot. It so happens that these are also the best mass produced PV panels the world over, thus lowering the production cost over the past years. Accordingly there are hundreds of brands and thousands of models in the market today.

How would you filter out the best suited Mono crystalline silicon PV modules for your installation?

There are at least seven major facets one has to look in to. These are;

• Specification

• Tolerance

• Electrical Performance

• Connections and terminations

• Physical dimensions and weight

• Characteristic performance curves

• Warranty and de-rating details over the useful lifetime

Specification

The specification would give you;

• the type of solar cells and their physical characteristics.

• The number of cells and the manner they are interconnected

• Typical nominal output voltage in DC

• Maximum voltage in DC

• Module dimensions (height x width x thickness)

• Structural details

• Thickness of glass front

• Cell efficiency %

Tolerance

The performance of the module will depend and vary between different parameters due to environmental and usage fluctuations. Therefore just like in other machinery there are tolerances it is possible and recommended too, to operate within. Some of the important ones are;

• Operating Temperature

• Hail dimensions the module can withstand against standard wind velocity

• Continued Wind Velocity tolerance

Electrical Performance

This is one of the most important set of data to evaluate suitability of solar PV modules for your specific requirements.

• Power rating (Pm) in watts

• Tolerance

• Rated current (Im) in amperes

• Rated voltage (Vm) in volts

• Short Circuit current (Isc) in amperes

• Open circuit voltage(Voc) in volts

• Nominal operating cell temperature(NOCT)

• Electrical Connections and cable terminations

Characteristic Performance curves

A reputed manufacturer will provide the electrical performance of a PV solar module in graphical form. This performance curve data is obtained under test conditions against a measured incidence of solar energy (such as 1000w/m2) and at a controlled cell temperature (such as of 25 0C)

Dimensions

Dimensions of PV modules along with their weight are very critical for example when installed on roofs, slabs and support structures. Another important fact is that the available mounting space may not be enough for the total number of modules needed for a particular building load depending on the module dimensions. Also it is critical to note whether the structural metal is of non- ferrous material and how bimetallic corrosion is avoided.

Warranty

Even a reliable product needs a warranty against at least manufacturing defects. It is your safe guard against a valuable investment.

While it is good for an owner interested in a renewable energy source for his home to understand what he can expect from a particular PV panel installation, it is always important to let the professionals handle the design, equipment selection, installation, commissioning etc.