A range of technologies exist to generate electricity on the basis of solar energy. The predominant one used today is photovoltaic (PV) technology. All current Origis Energy projects use solar PV technology.
What is solar energy?
The term photovoltaic is a combination of two words: “photo,” meaning light, and “voltaic,” meaning electricity. Photovoltaic technology is the term used to describe the hardware that converts solar energy into usable power, which generates electricity from light.
At the heart of PV technology is a semi-conductor material which can be adapted to release electrons, the negatively charged particles that form the basis of electricity. The main semi-conductor material used in photovoltaic cells is silicon, an element most commonly found in sand. There is no limitation to its availability as a raw material as silicon is the second most abundant material in the earth’s mass.
All PV cells have two layers of semi-conductors, one positively charged and one negatively charged. When light shines on the semi-conductor, the electric field across the junction between these two layers causes electricity to flow, generating DC (direct current). The greater the intensity of the light, the greater the flow of electricity.
A photovoltaic system therefore does not need bright sunlight in order to operate. It can also generate electricity on cloudy days. Due to the reflection of sunlight, slightly clouded days can even result in higher energy yields than days with a completely cloudless sky.
How does a grid connected photovoltaic system work?
How does a PV system work?
The basis of a photovoltaic system is a set of panel(s). Different panels are linked in a series called a “string.” The current created by the string or a combination of strings is routed to an inverter. An inverter inverts direct current (DC) into alternating current (AC). The AC current is metered and up-scaled to the voltage required for direct use on the premises or to be fed into the public grid.
The main characteristics of a PV system
The electricity produced by a photovoltaic system is dependent on its size, location and the quality of materials and installation. The output of a photovoltaic system in the short run depends on the weather conditions with direct sunlight being the main driver but temperature also has an impact (the hotter, the lower the production). Hence, predictability in the short run (daily basis) is low, except in regions with a very stable climate and predictable weather conditions. In the longer run, e.g. on a yearly basis, the output of a photovoltaic system is much more predictable. The variation in sunlight on a yearly basis is limited to about 5%.
A photovoltaic system requires low maintenance: periodic checkup and cleaning and incident intervention. Over time, the system is likely to be subject to a slight degradation of its performance. The panels usually come with a performance guarantee of 80% over 25 years. As a result of the above, the long term electricity produced by a photovoltaic system is highly predictable.
A photovoltaic system is not harmful to its environment since it doesn’t create noise, smell or pollution in any way.
How does a PV project make a positive contribution to the environment?
The production of electricity on the basis of PV-technology does not create any CO2-emissions. As the PV industry is a new industry with recently installed and efficient manufacturing processes, the CO2 created during the production is limited.
The electricity produced by the PV project replaces electricity otherwise produced by nuclear or gas or coal fired plants. Depending on the location of the project a PV system will reduce annual CO2 emissions between 600 tons and 1,400 tons per MWp installed, or the equivalent of 450 cars (driving an average annually of 15,000 km or some 9,000 miles).
Attractiveness of a PV project as a financial investment
Spurred by the threat of global warming and in order to reduce their dependence on nuclear power or fossil fuels, different countries have put in place incentive mechanisms to support the investment in PV projects. These incentives vary from country to country but most EU countries provide for a guaranteed price and off-take for the electricity produced by a PV system for a certain period of time, mostly 20 years. In the US, the incentives are more tax driven and require utilities to have a minimum volume of renewable energy in their production mix. The combination of such incentive programs with the operational characteristics of a PV system provide an excellent investment opportunity. Once the project is operational and enjoys the guaranteed off-take at the agreed price, the cash flow characteristics and hence the risk-reward relationship falls somewhere in between that of an investment in high quality real estate and an investment grade bond.
Key global and U.S. climate initiatives and solar
There are many ways solar energy generation contributes to a healthy environment.
The most important offset, key to all climate and clean energy initiatives, is the avoidance of further carbon dioxide (CO2) emissions, the most important greenhouse gas (GHG) pollutant.
- Calls for countries to reduce emissions enough so that global temperatures rise no more than 2 degrees Celsius, or 3.6 degrees Fahrenheit, by 2100.
- Outlines a global transition from fossil fuel industrial structure to renewable energy
- Each country committed to phasing out the use of fossil fuels while increasing renewable energy.
- Solar energy reduces GHG emissions compared with most other sources of energy. Carbon dioxide (CO2) is the most important GHG. Source: http://www1.eere.energy.gov/solar/pdfs/47927_chapter7.pdf
U.S. Clean Power Plan
Source: AWEA and SEIA, A HANDBOOK FOR STATES: INCORPORATING RENEWABLE ENERGY INTO STATE COMPLIANCE PLANS FOR EPA’S CLEAN POWER PLAN http://www.seia.org/sites/default/files/Handbook%20for%20States%20final_0.pdf
- States will need to use renewable energy emission reduction strategies in their section 111(d) compliance plans as part of an overall balanced energy portfolio
- Solar energy generation: one GWh of solar generation eliminates 690 metric tons of carbon dioxide (CO2) emissions.
- Solar energy generation has other environment benefits including the reduction of sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions however this level of environment offset information is not necessary to report in our opinion
- “SEIA urges states to recognize the speed of solar deployment, along with the modularity of solar, which makes it a great choice for meeting incremental generation needs and assisting states in quickly achieving compliance with EPA regulations under §111(d)”
U.S. Renewable Portfolio Standard (RPS)
- States across the country are enacting RPS policy.
- Not only are renewable energy policies, like the RPS, a cost-effective means to deploying renewable energy, but renewable energy is also a reasonable cost to utilities and ratepayers.
- A May 2014 joint study from LBNL and NREL analyzing the state level cost and benefits estimates from RPS policies found that “over the 2010-2012 period, average estimated incremental RPS compliance costs in the U.S. were equivalent to 0.9% of retail electricity rates when calculated as a weighted-average (based on revenues from retail electricity sales in each RPS state) or 1.2% when calculated as a simple average.
- Utilities are increasingly procuring solar energy because solar energy technologies, including utility PV, distributed PV, and CSP, have become reasonable cost resources when compared to other resources.
- Solar projects being offered and installed today show that solar is already cost-competitive with new and existing fossil generation in certain circumstances.
- Some of the most well-run and efficient companies are turning to solar energy to reduce their carbon footprint and hedge against risks associated with energy prices and climate change.