What is Renewable Energy?
Most of our "renewable energies" get their basic energy from solar radiation.
Wind is caused by the heating action of the sun; hydro relies on the hydrologic cycle (which relies on the sun); and geothermal is technically
"stored solar energy."
In a more general sense, "renewable energy" is any energy that is self-replenishing. For example, we do not need to find new 'reservoirs' of wind,
solar or geothermal energy.
What is PV?
The photovoltaic (PV) process converts sunlight, the most abundant energy
source on the planet directly into electricity. The equipment required for this process has no moving parts and as a result requires minimal maintenance. In addition, the electricity is generated with no emissions and no noise.
A PV cell consists of two or more thin layers of semiconducting material, most commonly silicon. When the cell is exposed to light, electrical charges
are generated and this can be conducted away by metal contacts as direct current (DC).
The electrical output from a single cell is small, therefore multiple cells are connected together to provide a more useful output. Cells connected in
this way are encapsulated (usually behind glass) to form a weatherproof module or panel.
Multiple modules can likewise be connected together in order to provide sufficient power for common electrical appliances.
How do solar photovoltaic cells work?
Photovoltaic cells are comprised of a semiconductor material such as silicon.
Added to the silicon are the elements phosphorous and boron which create conductivity within the cell and activate the movement of electrons.
The electrons move across the cell when activated by the sunlight's energy into the electrical circuit hooked up to the solar panel.
What does "energy conversion efficiency" mean?
Energy conversion efficiency is an expression of the amount of energy produced
in proportion to the amount of energy consumed, or available to a device. The sun produces a lot of energy in a wide light spectrum, but we have so far
learned to capture only small portions of that spectrum and convert them to electricity using photovoltaics. So, today's commercial PV systems are about
15% efficient, which might seem low. And many PV systems degrade a little bit (lose efficiency) each year upon prolonged exposure to sunlight.
Will solar work in my location?
Solar is universal and will work virtually anywhere, however some locations are better than
others. Irradiance is a measure of the sun's power available at the surface of the earth and it averages about 1000 watts per square meter. With typical
crystalline solar cell efficiencies around 14-16%, that means we can expect to generate about 140-160W per square meter of solar cells placed in full sun.
Insolation is a measure of the available energy from the sun and is expressed in terms of "full sun hours"
(i.e. 4 full sun hours = 4 hours of sunlight at an irradiance level of 1000 watts per square meter).
What components do I need?
There are many components that make up a complete solar system, but the 4 main items are: solar modules, charge controller(s),
batteries and inverter(s).
The solar modules are physically mounted on a mount structureand the DC power they produce is wired through a charge controller before it goes on
to the battery bank where it is stored.
The two main functions of a charge controller are to prevent the battery from being overcharged and eliminate any reverse current flow
from the batteries back to the solar modules at night.
The battery bank stores the energy produced by the solar array during the day for use at anytime of day or night. The inverter takes
the DC energy stored in the battery bank and inverts it to VAC to run your AC appliances.
Why install a PV system?
There are many reasons to install a PV system:
It is the most practical and economically viable option for many applications in remote areas.
It is completely pollution free. Installing a small domestic system of around 1.5 kW would provide around 1000 kWh of electricity every year,
this would save around half a tonne of CO2 annually.
Solar electricity generates energy without polluting the environment: no emissions, no noise and no waste. Solar panels require very little maintenance.
The amount of electricity produced by a solar system varies depending on the amount of sunlight available yet it produces long-term, reliable electricity.
Do you really think solar and renewable energies are a good investment?
Yes. Solar energy and other forms of renewable energy (such as geothermal) will become cheaper as people continue to invest in them.
When people invest in them, this will drive down the cost- as it already has over the last few decades. This has a snowball effect: the technology becomes
increasingly usable, cheaper and convenient.
Why are PVs rated in Wp rather than watts?
Wp means peak Watts. In other words, a 100Wp panel will produce a maximum
of 100W in peak conditions (1kW/m2 solar irradiation) - this is equivalent to a bright sunny midsummer day UAE.
Should I wire my home for AC or DC loads?
It depends on the size of the system and what type of loads you want to run.
DC appliances are usually more efficient than AC since you don't have to worry about the loss through the inverter,
but DC loads are typically more expensive and harder to find than their AC counterparts. Small cabin and RV systems are typically wired DC while most
home systems are wired for AC loads exclusively. With improvements in inverter efficiency and reliability in the last 5 years,
AC is the way to go for a home system. Another advantage AC has over DC is that the voltage drop for a 120VAC circuit is much less than a
12VDC circuit carrying the same power, which allows you to use smaller gauge wire.
What is solar energy?
Solar energy takes advantage of the sun's rays to generate heat or electricity.
It is an infinitely renewable resource and unique for its ability to generate energy in a quiet, clean, and consistent manner.
Can't beat the sun for being oh-so-cool!