GENERAL Q.: > What is renewable energy?
- Renewable energy refers to power harvested from natural resources, such as the sunlight, wind, water, and geothermal heat, which are renewable (naturally replenished) and are not in danger of being depleted. The five fundamental renewable energy sources are:
- Solar: radiant light and heat absorbed from the sun and converted to electricity through photovoltaics or to thermal energy
- Wind: energy harnessed from wind by wind turbines for electricity, wind mills for mechanical power, and wind pumps for pumping water or drainage
- Geothermal: power extracted from heat stored in the earth
- Hydropower: energy derived from the force of moving water
- Biomass: electricity or heat produced from living, or recently living organisms, such as wood, waste, (hydrogen) gas, and alcohol fuels
SOLAR Q.: > What is PV?
- PV stands for photo (light) and voltaic (electricity). Solar electric panels are made of photovoltaics cells–PV for short. Photovoltaic (PV) cells convert sunlight to electricity. The basic building block is known as a cell. Many cells put together form a module, and many modules an array. A PV system consists of an array of modules generating DC electricity, an inverter, and sometimes battery storage as a backup. A single module is enough to power an emergency telephone, but for a house or a power plant the modules must be arranged in multiples as arrays.
SOLAR Q.: > Why solar and what is power of the sun?
- Solar because almost all of the energy that drives the various systems (climate systems, ecosystems, hydrologic systems, etc.) found on the Earth originates from the sun. Solar electricity is abundant, unlimited and free; clean; reliable and efficient; silent; renewable; provides energy security and independence; and needs no maintenance. The usage of renewable power reduce volatility and lower cost of electricity.
- The Sun is the source of almost all energy used on Earth. Every hour the Earth receives more energy from the Sun than the world uses in a whole year. The energy from the sun varies from place to place and depends on the geographic location, time of day, time of year, and weather conditions. Without an atmosphere 1.4 KW/m2 per hour is available, but with an atmosphere we can only count on 1KW/m2 per hour in the absence of clouds. All energy stored in Earth's reserves of coal, oil, and natural gas is matched by the energy from just 20 days of sunshine. Averaged over Earth's surface, each square meter collects the approximate equivalent of almost one barrel of oil each year, or 4.2 kWh (kilowatt-hour) of energy every day. If we combine this powerful energy source with other renewables, like wind, hydropower, geothermal, and biomass it seems unbelievable that human population depends on fossil fuels to meet our energy demands.
SOLAR Q.: > What are types of solar energy?
- Solar energy can be converted into other forms of energy, such as heat and electricity. Solar energy converted to thermal (or heat) energy can be used to heat water and spaces. Sun's energy converted to electricity by photovoltaic (PV devices), also called solar cells, converts sunlight into direct current. Solar power plants indirectly generate electricity when the heat from solar thermal collectors is used to heat a fluid which produces steam that is used to power generator. Depending on the way solar technologies capture, storage, convert, and distribute sunlight they are called active or passive. The technology evolution for capturing solar energy began with passive solar centuries ago. Next was the origination of solar thermal technology and lastly photovoltaic development.
SOLAR Q.: > How does a solar panel work and how is it different from a solar collector?
- The sunlight that hits the solar panel is converted into direct current (DC). To be compatible with power appliances and synchronized with utility power or to recharge a battery and be stored as a backup, DC power is converted into alternating current (AC) by inverter. If more electricity is generated than consumed then the utility meter spins backward, sending unused power back to the electric supplier for credit.
- Solar Collectors transform short wavelengths into long wavelengths and trap this energy in the form of heat which is transferred and transported into a heat storage vault.
- Solar panels convert selected wavelengths of light into electricity.
SOLAR Q.: > What are the main components of the solar system?
- The main components of the on-grid solar system are:
- Solar panels (photovoltaic (PV) cells assembled together in modules and arrays) that generate direct current (DC) electricity;
- DC-AC power inverter that transforms DC into alternating current (AC) electricity and provides safety functions;
- Meter to provide energy usage and system performance indication;
- Surge protection and disconnect devices, such as manual safety switch to disconnect building's electricity installation from the solar system if needed;
- Monitoring and reporting system to link all components and measure and monitor the generated power;
- Other components depending on local conditions.
- Batteries are often used in PV systems as a backup to store energy generated by PV system or to keep stable voltages. Battery charge controllers are often used to protect the battery from overcharge and overdischarge.
SOLAR Q.: > What is an inverter?
- Solar inverter or PV inverter is an electrical device that converts direct current (DC) electricity from a photovoltaic array into alternating current (AC) for use with appliances and a utility grid. The converted AC can be at any voltage and frequency with the use of appropriate transformers, switching, and control circuits. The DC side is called an input and AC side – output. Utility companies provide AC electricity to power buildings. DC is used by batteries, e.g. in flashlights, small radios and vehicles. An inverter converts the DC electricity from batteries, solar panels, or fuel cells to AC electricity. Inverters use batteries (UPS) or the utility grid as power storage (Grid-tied). Grid tie inverters can feed energy back into the distribution network because they produce alternating current with the same wave shape and frequency as supplied by the distribution system. They can also switch off automatically in the event of a blackout. Micro-inverters convert direct current from individual solar panels into alternating current for the electric grid.
SOLAR Q.: > What is solar panel efficiency?
- Since the amount of available electricity depends on location, time, and weather, the amount of power generated is proportional to the number of panels and the type/efficiency of the panels. Solar panel efficiency is the percentage of the solar energy converted into electricity and collected in the circuit. The efficiency of a solar cell may be broken down into reflectance efficiency, thermodynamic efficiency, charge carrier separation efficiency and conductive efficiency. The overall efficiency is the product of each of these individual efficiencies. The mono-crystalline cells have the highest efficiency about 14-17% (up to 25% in lab) but the manufacturing process is energy-intensive and wasteful. The multi-crystalline cells efficiency range from 13-15% (up to 18% in lab) and production costs are lower. The amorphous (thin film) cells efficiency range from 5-7% (up to 13% in lab), so they are the least efficient but much simpler and cheaper to manufacture. String ribbon, the new proprietary technology has an efficiency of 7-8% and it's relatively inexpensive. Currently there are many other than silicon materials under development and researches are focused on obtaining higher efficiencies to reduce the cost of solar electric power.
SOLAR Q.: > What is SPPA?
- Solar Power Purchase Agreement (SPPA) is a long-term arrangement between an electricity provider and a power purchaser. Solar PPA providers own, install, operate and maintain photovoltaic (PV) systems on customer rooftops and properties. Host customers receive stable, and often low-cost electricity and pay for the generated electricity only, while the solar services provider or another party acquires valuable financial benefits such as tax credits and income generated from the sale of electricity to the host customer.
SOLAR Q.: > Is my building ideal for solar electricity (photovoltaic)?
- Typically, an unobstructed south facing roof space makes an ideal site for a solar system. Whether the facility has a flat or slant roof solar photovoltaic technology can easily be integrated. Often an east-west roof with good exposure, or even a ground mounted system can work just as well. Shading on the surface that is intended to install solar panels on, may reduce the effectiveness of the PV system.