About Solar

Overview
Benefits of Solar
- Why Go Solar?
- Why Is Solar Energy Important?
- What Can Solar Do for You?
Brief History of Solar PV Technologies

Overview
What is Solar Energy?

Solar Energy is energy radiated from the sun, mainly in the form of heat and light. It is required for photosynthesis and is also harnessed as a renewable energy source, e.g. in photovoltaics (PV) to provide electricity or as solar thermal energy for heating and cooling systems. Solar energy can be used in homes, businesses, and industry as well as in distributed generation applications, such as street lighting or for back-up electricity generation. On a bright, sunny day, the sun provides approximately 1,000 watts of energy per square meter of the planet's surface, and if we could collect all of that energy we could easily power our homes and offices for free. [back]

Benefits of Solar
Why Go Solar?

1. Solar PV or solar hot water systems reduce, or can completely eliminate, the amount of electricity you have to purchase from your utility or electric service provider to power your home. Using solar power helps reduce our energy reliance on fossil fuels.
2. The electricity generated by your solar power system is clean, renewable and reliable. It will help reduce the amount of greenhouse gases – a major contributor to global climate change.
3. Solar PV or solar hot water systems save you money on your electricity or natural gas bill and act as a hedge against future price increases. Solar power systems can provide owners with fixed energy costs.
4. A growing solar industry provides local jobs and economic development opportunities for states and regions.
5. Using solar PV power helps your community by reducing electricity demand and providing additional electricity for the grid when you generate more than you use during the day, when the demand is highest. [back]

Why Is Solar Energy Important?

Solar energy systems have very little impact on the environment, making them one of the cleanest power-generating technologies available today. While they are converting the sun’s rays into electricity or hot fluids, they produce no air pollution, hazardous waste, or noise. The more electricity and heat that we convert from the sun’s rays decreases our reliance and dependence on fossil fuels and on imported sources of energy. Finally, solar energy can be an effective economic development driver. [back]

What Can Solar Do for You?

Photovoltaic (PV) power systems convert sunlight directly into electricity. A residential PV power system enables a homeowner to generate some or all of their daily electrical energy demand on their own roof, exchanging daytime excess power for future energy needs (i.e. night time usage). The house remains connected to the electric utility at all times, so any power needed above what the solar system can produce is simply drawn from the electric utility. Solar energy technologies can plan an important role in providing an alternative source of electricity, energy, and back-up power for homes, offices, commercial and industrial buildings. It can relieve demand pressures for electricity off from the grid during peak usage, which usually correlates to peak daylight, especially in the warmer months when demand for air conditioning can sky rocket.

Solar energy can also play an important role in lowering greenhouse gas (GHG) emissions by replacing coal-powered energy sources with clean, renewable solar PV technologies. These GHG emissions reductions will in turn improve air quality and lessen the harmful impacts that contribute to climate change.

Those who are putting solar on their homes, businesses or other buildings are making a difference. [back]

Brief History of Solar PV Technologies

Sunlight is the world’s largest energy source and for thousands of years, it has been human civilization's chief source of light and heat. Today, solar energy technologies are being developed and refined to more effectively use the sun’s power for producing electricity (photovoltaics), as well as steam and hot water for industrial processes (solar thermal technologies). In less than an hour, the U.S. receives more energy in the form of sunlight than it does from the fossil fuels it burns in a year.

The roots of PV energy grew out of experiments done over 150 years ago by the French physicist Antoine-Cesar Becquerel in 1839. He observed that he could produce an electric current by shining light on an electrolytic cell composed on an electrolyte and two electrodes. The German scientist Heinrich Hertz and other observed the PV effect – the conversion of light into electricity – in solids during the 1870’s, and the first primitive PV cells were built in the 1800s, with about 1-2 percent efficiencies. In 1954, Bell Labs in the U.S. introduced the first solar photovoltaic device that produced a useful amount of electricity, and by the late 1950s solar cells were being used in small-scale scientific and commercial applications, especially for the U.S. space program.

Photovoltaics, or PV for short, is a technology in which light is converted into electricity using photovoltaic modules that have no moving parts, operate quietly without emissions, and are capable on long-term use with minimal maintenance. Crystalline silicon, the same material commonly used by the semiconductor industry, is the material used in 94% of all PV modules today. PV modules generate direct current (DC) electricity. For residential use, the current is fed through an inverter to produce alternating current (AC) that can be used to power the home’s appliances. The main barrier to widespread use of this technology is the initial high equipment cost. PV technology was been advancing over the last few decades and prices have steadily declined.

Photovoltaics is a fast-growing market: The Compound Annual Growth Rate (CAGR) of cumulative PV installations including off-grid was 34% between year 2010 to 2020. In year 2020 producers from Asia count for 95% of total c-Si PV module production. China (mainland) holds the lead with a share of 67%. Europe contributed with a share of 3%; USA/CAN with 2%. Wafer size increased enabling larger PV module size allowing a power range from +600 W per module. In 2020, Europe's contribution to the total cumulative PV installations amounted to 22% (compared to 24% in 2019). In contrast, installations in China accounted for 33% (same value as the year before). Si-wafer based PV technology accounted for about 95% of the total production in 2020. The share of mono-crystalline technology is now about 84% (compared to 66% in 2019) of total c-Si production. Market shifts from subsidy driven to competitive pricing model (Power Purchase Agreements PPA).

The record lab cell efficiency is 26.7% for mono-crystalline and 24.4% for multi-crystalline silicon wafer-based technology. The highest lab efficiency in thin film technology is 23.4% for CIGS and 21.0% for CdTe solar cells. Record lab cell efficiency for Perovskite is 25.5%. In the last 10 years, the efficiency of average commercial wafer-based silicon modules increased from about 15% to 20%. At the same time, CdTe module efficiency increased from 9% to 19%. In the laboratory, best performing modules are based on mono-crystalline silicon with 24.4% efficiency. Record efficiencies demonstrate the potential for further efficiency increases at the production level. In the laboratory, high concentration multi-junction solar cells achieve an efficiency of up to 47.1% today. With concentrator technology, module efficiencies of up to 38.9% have been reached.

Material usage for silicon cells has been reduced significantly during the last 16 years from around 16 g/Wp to about 3 g/Wp due to increased efficiencies, thinner wafers and diamond wire sawing as well as larger ingots. The Energy Payback Time of PV systems is dependent on the geographical location: PV systems in Northern Europe need around 1.2 years to balance the input energy, while PV systems in the South equal their energy input after 1 year and less, depending on the technology installed and the grid efficiency. A PV system located in Sicily with wafer-based Silicon modules has an Energy Payback Time of around one year. Assuming 20 years lifespan, this kind of system can produce twenty times the energy needed to produce it.

Inverter efficiency for state-of-the art brand products is 98% and higher. The market share of string inverters is estimated to be 64%. These inverters are mostly used in residential, small and medium commercial applications in PV systems up to 150 kWp. The market share of central inverters, with applications mostly in large commercial and utility-scale systems, is about 34%. A small proportion of the market (about 1%) belongs to micro-inverters (used on the module level). The market share for DC / DC converters, also called "power optimizers", is estimated to be 5% of the total inverter market. Trends: Digitalisation, Repowering, new features for grid stabilization and optimization of selfconsumption; storage; utilization of innovative semiconductors (SiC or GaN) which allow very high efficiencies and compact designs; 1500 V maximum DC string voltage.

In Germany prices for a typical 10 to 100 kWp PV rooftop-system were around 14,000 €/kWp in 1990. At the end of 2020, such systems cost only 7.4% of the price in 1990. This is a net-price regression of about 92% over a period of 30 years. The Experience Curve – also called Learning Curve - shows that in the last 40 years the module price decreased by 26% with each doubling of the cumulated module production. Cost reduction results from economies of scale and technological improvements. [back]