Solar Energy Facts

Solar energy facts category is a collection of articles relating to solar energy with a focus on interesting facts about solar energy and green power. Sub categories include solar technologies such as solar panels, solar energy findings for 2012, information regarding solar panels cost, home solar panels and facts about solar energy systems. The following solar energy facts have been summarized under different group headings and organized in short bullet form; standalone facts about solar energy:

Interesting facts about solar energy and the sun

  • The size of the sun is about 1 million times larger than Earth – that is the diameter of the sun is 1,392,000 km compared to the diameter of earth being just 12,756 km – which is about 109 times smaller; for comparison you may consider that the sun can contain upto 1,000,000 earths!
  • The speed of light travels at about 299,792,458 meters per second – i.e. approximately 300,000 km per second or (1 billion km per hour!)
  • Light traveling from the sun takes about 8.2 minutes to enter the earth atmosphere covering a distance of approximately 150 million kilometers – or 8.2 light minutes.
  • Assuming 100% absorption of solar energy, it takes about 88 minutes of solar radiation to cover for overall human energy consumption for a whole year!  However, actual absorption of solar radiation is limited to about 1% leaving 99% of solar radiation energy being wasted – see: solar energy potential in solar energy facts.
  • Solar energy striking the Earth goes about 50% absorbed by Earth itself while 30% of solar energy is being reflected back into space.
  • The average direct solar radiation (subject to exact location and angle of solar radiance) is estimated at about 1.37 kw per square meter (1370 watts per square meter).

 Solar Power facts and solar energy systems – Green house gas equivalents

  • Solar energy can be used with renewable solar technologies to replace conventional energy systems that consume fossil fuels, thus help reduce harmful emissions into the atmosphere and help reduce greenhouse effect and global warming.
  • A 10 kw solar panel installation (under certain conditions) is estimated to generate about 17,000 kwh in a year. In environmental terms, this is equivalent to avoiding the emission of 11.7 metric tons of Carbon Dioxide (CO2) into the atmosphere. To help you understand this in real terms consider the following equivalent statements:
  • Equivalent to the greenhouse gas emissions of approximately 2.3 cars in a year.
  • Equivalent to CO2 emissions from burning 27.3 barrels of oil
  • Equivalent to the CO2 emissions from the annual energy use of a house.
  • Solar energy can be used indirectly as stored thermal energy or directly for generating electricity with solar photovoltaic panels; stored thermal energy can in turn be used for supplying hot water for use, for space heating ( and cooling – solar cooling) or for indirect electricity generation – as in concentrated solar power (CSP).
  • An example of direct and indirect solar energy system is by comparing solar Photovoltaic panels (PV) and Concentrated Solar Power (CSP) technologies, in CSP vs PV.

Facts about Solar energy systems and usage

  • Solar Energy is used in a variety of applications through different technological configurations such as:
  • Solar hot-water heater – solar heating elements: for heating of water for supply of hot water in buildings, or for heating of water or other liquid for space heating in buildings (e.g. in under-floor heating elements)
  • Solar Photovoltaic panels (PV panels) for generation of electricity through a direct solar energy system – Such applications may range from small domestic solar panel systems (pros and cons of home solar panels) to large utility scale systems (for the production of electricity at the community level).
  • Concentrated solar power (CSP) – for the generation of electricity mainly at large scale; this is an indirect electricity generation process as solar energy is converted into thermal energy and is stored in thermal tanks. Thermal energy is then used to generate hot steam to drive a steam turbine and generate electricity.
  • Passive solar energy systems – for increasing the efficiency of the energy performance in buildings. Passive solar energy systems do not use any ‘active’ or mechanical parts (as in the case of solar panels); instead they utilise thermal solar energy ‘passively’ – e.g. a thermal wall which is ‘charged’ by solar radiation.
  • Some other Solar energy system applications include solar lighting (indoor and outdoor), supplying power to electrical devices at all sizes – e.g. from small calculators to large power boats, planes or cars. Another use of solar power is for cooking food; this can be accomplished by using special cooking pans designed to amplify solar heat for cooking food  – solar (heating) pans, etc.

Facts about solar energy systems for home

  • Grid-tide solar panels installations for homes are estimated to cost about $3-$4 per wattage of installed capacity – see solar panels for home
  • Remote solar panels installations have a higher cost than grid-tied solar energy systems as they require extra equipment to store electricity in batteries.
  • Feed-in-tariffs (Fits) are subsidy schemes to motivate installations of solar energy panels for the production of solar energy (electricity). FITs aim to provide an incentive
  •  towards promotion and adoption of solar energy systems through offsetting the cost of extra investment for installing the solar panels– A feed in tariff is the rate in $/kw at which the government or other authority pays for the production of electricity produced from solar energy – a renewable energy source.
  • 45% of residential energy consumption in the US was for space heating and 18% for water heating – (total of 53%). The rest 47% was consumed for space cooling, lighting, electronics, refrigeration, computer and others (source residential site energy consumption by use – US – DOE – data for 2009).

 Facts about Photovoltaic solar panels

  • Solar PV panels have an efficiency of about 15% – i.e. they are able to convert to electricity only 15% of the solar energy (sunlight) they are exposed to.
  • The lifetime of solar panels (photovoltaic panels) on average ranges between 20-25 years – different solar panel companies may give different guaranties for the performance and operation of their solar panels.
  • Solar panel efficiency is a function of surrounding temperature and panel age – solar panels may have a reduction in their efficiency equal to 1% for every degree Celsius rise in temperature above standard conditions (specified by manufacturer of the solar panel).
  • Solar panel companies may give performance guaranties for the efficiency of their solar panels across the panel’s lifetime; an indicative performance guaranty is 10 years with maximum loss of 10% on power rating and 25 years with maximum loss of 20% on power rating.
  • Solar panels cost in 2012 ranged between $1,700 to $2,500 per kw of installed capacity – prices refer to solar panels for residential solar panels in 2012 – see article on solar panels cost.
  • A solar panel with capacity of 1kw can produce, on average, between 1,500kwh and 1,750 kwh in one year – these figures refer to conditions similar to California and Southern EU.

 Some interesting solar energy facts for kids

  • The basic solar energy systems include:
  • Solar Thermal systems for water and space heating in buildings (used in houses or commercially)
  • Solar Panels (solar Photovoltaic (PV) panels for generation of electricity (used in both utility scale and residential solar energy applications)
  • Solar Thermal systems (CSP – concentrated solar power) for electricity generation (used in power generation and large electricity generation applications)
  • Other configurations exist, combining solar energy systems with other renewable energy technologies or with other conventional power systems (e.g. co generation of electricity).
  • A recap of the main advantages of solar energy systems:
  • Solar energy is free and abundant energy supplied by nature itself
  • Solar energy systems are environmentally friendly – as an alternative green energy source.
  • Solar panels (photovoltaic PV panels) can be easily placed in residential areas (residential solar panels) in on or off grid installations
  • On grid solar panel installations supply generated electricity to the power network
  • Off-grid solar panels store generated electricity for own use – e.g. in country farms and remote areas.
  • Solar panels cost has been falling and is expected to continue on a diminishing turn in the future; this means that PV panels will gradually become economically more viable – not in need of any subsidy incentives.
  • Solar Photovoltaic (PV) panels constitute a mature technology; PV panels are a reliable technology
  • A recap of the main disadvantages of solar energy systems:
  • Solar energy is directly dependent on weather conditions; thus solar energy without any energy storage equipment (especially in cloudy, rainy weather conditions) is considered highly unstable and unreliable energy source.
  • The cost of solar panels (cost of solar energy systems in general), though on a diminishing trend, is still high compared to conventional alternatives – that is why, solar energy systems need to be supported by financial incentives for solar energy initiatives – to off-set their initial investment.
  • Not all advantages of solar energy sources apply to all solar energy technologies; e.g. Solar Photovoltaic panels exhibit different behaviour than solar thermal systems – you may refer to solar energy pros and cons.

Learn solar energy facts

You can test what you have learned by having a go at these simple questions listed below:

(hint: try giving an answer before scrolling back in the article to find an answer).

  •  In theory, how many earths can you fit in the sun?
  • What is the sun diameter?
  • What is the speed of light?
  • What are the main uses of thermal energy?
  • Name (3) three different solar energy systems utilizing solar energy
  • What are FITs?
  • What is the main source of energy consumption in residential energy consumption?
  • What is the efficiency of PV panels?
  • What is the recently updated cost of solar panels per kw?
  • How many Kwh can a 1 kw solar panel produce in a year?
  • What are 2 main advantages of solar panels?
  • What are 2 main disadvantages of solar panels?