Date post: | 13-Aug-2015 |
Category: |
Environment |
Upload: | mathy-mpassy-isinki |
View: | 299 times |
Download: | 8 times |
Solar PV basics
Energy One Ltd
By Mathy Mpassy Isinki
Off Grid Energy Solutions Business andTechnical Sales Professional
Grid connected solar PV systemsbenefit from grid's energy while;Off grid solar PV systems benefit fromenergy stored into batteries.
When the sun is not available:
Photovoltaic (PV) cells are made oflight sensitive semiconductor materialsusing photons to dislodge electrons anddrive an electric current.
Mono-crystalline silicon;Poly- crystalline;Thin films
There are three main type of PV cellstechnology in use:
Crystalline silicon is made from ultrapure silicon material such as the one usedfor semiconductor chips;
Thin films is made by depositing layers ofsemiconductors material onto glass orstainless steel substrate.
Mono-crystalline silicon: 12.5-15%Poly-crystalline silicon: 11-14%Copper Indium Gallium Selenide (CIGS): 10-13%Cadmium Telluride (CdTe): 9-12%Amorphous Silicon (a-Si): 5-7%
Solar cells conversion efficiency:
Crystalline silicon: -0.4 to -0.5CIGS: -0.32 to -0.36CdTe: -0.25a-Si: -0.21
Solar cells temperature coefficient:
Solar power terms:
Pmax: The maximum power a solarmodule can produce.Vpmax: The voltage at whichmaximum power is produced.Ipmax: The current at which maximumpower is produced.
Voc: The maximum possible voltageacross the solar module when current iszero.Isc: The maximum possible currentflowing through the solar panel whenno load is connected and voltage iszero.
Standard Test Conditions (STC):
Temperature of the cell – 25°C.Solar Irradiance – 1000 Watts persquare meter.
PV modules are connected in series into PVstrings;
PV arrays are formed by the parallelaggregation of PV strings.