Solar Energy Conversion
Drops of energy …
Light is made of photons, carrying enough energy to extract electrons (electrical charges) from semiconductors like silicon.
Unlike thermal collectors, that convert sunlight into heat, the solar cells and the photovoltaic modules produce DC (direct current) electricity directly when exposed to sunlight.
Why “Light” & solar energy ? Because any source of light can be converted into electricity, even indoor artificial light see our Indoor solar cells.
Amorphous / crystalline silicon & other materials
Why sand loves sun … and not only in the desert…
The most common photovoltaic material is mono- or poly-crystalline silicon, because of its huge availability on earth (in the sand), its good electronic quality and its higher efficiency under sun exposure. It well suited for more than 20-50Wc modules and high illumination conditions.
But, its little brother the amorphous silicon and its derivatives (microcrystalline and polymorph silicon, all in film films) have very specific features :
Excellent sensitivity under medium and low illumination (artificial light, cloudy weather…)
Easy production on small sizes at any voltage and dimensions
Less drop of efficiency at high temperature (unless crystalline silicon)
Energy storage for off-grid systems
Why store into a rechargeable battery ?
As the light into electricity energy conversion is in real time only, itis necessary to store the energy as soon as electricity is needed in the dark, or when the consumption at a given moment is higher than the production coming out the solar converter.
The role of a battery in solar power system :
- It feeds the equipments during the night
- It absorbs current peaks (during a motor start for ex.)
- It feeds partly the equipments in case of bad weather.
Description of a solar off-grid power system
A photovoltaic power system contains :
- A (or several) solar photovoltaic module(s)
- A charge regulator adapted to the solar power
- A Lead acid battery, sealed or not; according to the expected lifetime, the required capacity, and the possible maintenance
- DC/DC or DC/AC converters if necessary
SOLEMS designs your solar systems according to YOUR SPECIFICATIONS :
- reliability first,
- and cost effectivenes.
What is the regulator for ?
Sometimes, a photovoltaic system provides more energy than required, especially during summer. If the solar panel is connected directly to the battery, it can damage it by overcharge.
Besides, when an incident occurs that leads to an energy deficit : excessive consumption, broken panel, …etc… the battery can be in a situation of excessive discharge. In some cases, it is better to cut the service than to damage the battery by deep discharge. Because a very deep discharge can destroy it completely.
The regulators, or controllers, or charge limitors are meant to avoid these problems, they protect the battery. It is also a way to get an overall lifetime of pv off-grid systems. Because the panels generally have a natural longer lifetime than the battery.