Categories: Know HowSolar Energy

Solar Power | Electrical energy from the sun

Solar Power – Electrical energy from the sun. As humans we need sunsine to live. Our technology also “lives” largely from it. Solar radiation and wind are free to collect. They are always there to make a use for it. It’s a part of renewable energies sources for the future.

Sun energy in Portugal is a fast upcoming market. Enjoy it with a small scale solar energy battery storage production on your roof or backyard.

Solar Power | Electrical energy from the sun

It comes through nuclear fusion, when hydrogen is converted into helium. Sun is the source for geological processes on earth. Without it there would be no wind, there would be no water cycle, and no life would be possible. The amount of power that it produces is gigantic.

Every second there is enough free fuel production to provide the Europe with 50 million years of solar electricity.

The sun provides direct fuel sources in two forms, light and heat. It's generated by the enormous pressure exerted on the core. These two forms together with the secondary structures, such as wind, tides, hydropower and biomass, make up 99.9% of the power on earth.

The atmosphere and magnetosphere protect the earth against the most harmful radiation. However, the released energy that reaches us is still 9000 times greater than the needs of all earthlings combined.

Solar power is the conversion of energy from sunlight into electricity, either directly using photovoltaics (PV), indirectly using concentrated solar instalations, or a combination. Photovoltaic cells convert light into an electric current using the photovoltaic effect.[1]

What is sunlight energy.

Sunlight consists of different colours that are absorbed by the photovoltaic cell. The size of absorption is determined by the semiconductor material used. From which a photovoltaic cell is built. Such a material is not equally sensitive to all colours.

PV panels mainly use visible light (about 45% of the light), light that we can observe with our eyes. Light consists of photons (= the light particles from the radiation = energy packages) that determine the colour.

The photon must have a minimum amount needed to release electrons in the semiconductor material. If the power is higher than the required minimum, the excess thermal energy is published in the form of heat. Approximately 55% is lost in the light in this process. Then the electrons will fall back to their old state.

The theoretically possible conversion efficiency is therefore not higher than 20-30%.

At the moment, the very best small photovoltaic cells with an optimal colour sensitivity at laboratory level have a yield of at most 32%. The commercially produced photovoltaic cells currently have a return of between 6% and 16%. Amorphous silicon photovoltaic panels (thin film) have a yield of between 6% and 8%, mono-crystalline PV panels give 15% to 16%, and polycrystalline PV panels give an efficiency of approximately 14%.

Solar Power | Electrical Energy from the sun

Solar power is the most direct way to harvest the energy. We do this via photovoltaic panels and collectors. The wind is created because it is warmer in one place than on the other.
Even water power depends on it. Hydropower plants use the flow or fall of water from top to bottom. Just as water mills used to do.

But who brings the water up? Thanks to the heat of the sun, the water evaporates. The water rises and when the clouds cool down it rains or snows. That water flows down from the mountains again and there we build our hydropower plants.

PV panels convert sunlight into electricity (PV power). It is a readily applicable and environmentally friendly technique for generating electricity. Too much electricity generated can easily be supplied to the electricity grid.

There are also more and more products on the market, in which photovoltaic cells are integrated into building materials, such as roofing, façade panels or roof tiles. PV panels last 30 – 35 years. Generally, the PV panel manufacturers guarantee that the PV panels will still produce at least 80% of the original yield after 25 years.

Photovoltaic energy power systems.

There are two types:

  1. Autonomous systems: these solar systems are not connected to the grid, the electricity is supplied to a battery or directly to a device, for example, a pump or a vehicle to grid car. This involves direct current (DC = Direct Current).
  2. Network-connected PV systems: the electricity is supplied to the public electricity grid. To be able to do this, the direct current must first be converted into 230 volts alternating current (AC) using an inverter.

Portuguese sunlight is ideally suited to generate sustainable electricity. It delivers clean energy that never runs out. Solar cells convert that light into clean and free energy. Good for the global warming and for your wallet.

Germany, Spain and Portugal are investing in the energy companies. There are photovoltaic power plants. Huge installations of PV panels that generate electricity. Portugal has thermal plants. The word thermal indicates that they use the heat to eventually make electricity.

The power plants consist of hollow mirrors that combine the sunlight to heat up liquid and develop steam. Turbines will be driven by the steam force. There are also thermal plants in Spain. Another name for it is Concentrated Power plants.

A disadvantage of thermal plants (Concentrated Power plants) is that they require a lot of water to cool the steam in the turbine. Every 1,000 kWh costs 3 m3 of water, which can not be reused because it just evaporates.

Large-scale solar panels (‘solar parks’).

In Spain and Germany, large plants with thousands of square meters of photovoltaic panels have been built with a subsidy. The capacity of such solar PV systems amounts to more than 1 MWp (megawatt peak). One MWp is 1 million watt peak.

In Portugal, more and more such large parks are now being built, from every Wp to dozens of MWp. The photovoltaic cell systems are arranged in rows or in a so-called tracker system. Trackers each contain 12 panels and rotate along with the position of the sun so that the light is always optimal.

Concentrated Power plant with mirrors.

A Concentrated power plant is a thermal system that uses that heat. When you combine sunlight at one small point, the light energy concentrates and the temperature can rise quickly. This allows you to bring water to the boil, which produces steam. Steam power can drive a turbine again.

That is in short how Concentrated Solar Power (CSP) works. Since electricity comes from heat and not from a photovoltaic reaction, it is called a solar thermal power plant.

In Spain, for example, curved mirrors are in the form of a feeding trough. The mirrors direct sunlight on a pipe that is filled with thermal oil.

The oil, therefore, becomes heated to more than 400 degrees Celsius. Through a heat exchanger, the oil transfers the heat to water, which starts to boil. The pressure created by the steam then drives a turbine, which finally produces electricity.

Concentrated solar photovoltaic plants.

As with Concentrated power electricity plants, they use light bundling to concentrate on a small surface. They do this with mirrors in the form of dishes. The difference with CSP is that electricity is generated by a photovoltaic reaction, not by heat. The mirrors reflect the light at a small collection point of specialised, highly efficient photovoltaic cells.

Larger energy productions yield with dishes.

With concentrated plants you can generate a high energy production with a minimal panel surface. A 35-watt peak panel (35 kWp) requires a panel of only 0.23 m2. While a traditional system for the same power requires about 350 m2 of cells. Each photovoltaic panel has its own cooling. The efficiency of light conversion to electricity decreases rapidly as the cells warm up.

Do humans use too much solar energy?

Concentrated solar projects plants have a capacity between a 10-megawatt peak (10 million watt peak) and some gigawatt peak (1-gigawatt peak is 1 billion watt peak).

  • Saving or balancing solar electricity:
    More and more households generate electricity with photovoltaic systems themselves. The feed in tariffs are an important rol for youre investment. But in that way you are doing well for the environment, because the energy is clean and sustainable.
    But it only shines during the day, while you also use electricity in the evening. Fortunately, you can return power that you do not use during the day to the power supply. You will receive compensation for this.
  • Store in water:
    In Lagos Algarve a trial with 200 households is running under the name ‘City of the Sun’, which immediately converts energy with a new technique. By, for example, heating up water during the day and using it at night, the residents deal more efficiently with their self-generated energy.
    The nice thing is, they don't have to do anything for it. The equipment itself will figure out what the best way is to park and to retrieve it.
  • Store in batteries:
    Car manufacturers have been experimenting for years with batteries to drive electric cars. The same technique is used at home to store electricity. There are a few drawbacks here. For example, the capacity of the batteries is somewhat limited. Moreover, they are still quite expensive.
    Also, its production and the final processing of the battery (when it breaks down for example) is damaging to the environment. Scientist try to improve this technique every day. Sometimes they break through.

What are advantages of solar energy?

Not all the sunlight can be used to generate solar energy. The materials from which photovoltaic cells are made reflect or absorb a large part of the light. As a result, a commercial solar panel now has an efficiency of about 27%. So only about one-sixth of all the light that reaches the panel.

Improving the efficiency is one of the areas that researchers are now focusing on. The progress in efficiency that is been achieved, is impressive. The first photovoltaic cells, built in the fifties, had an efficiency of only 4%, or less.

The different forms of solar technology offer many applications. In principle, it is possible to get all the energy that you use at home, electricity and thermal heating! In the Algarve portugal it is commen to heat up swimming pools.

The ongoing innovation in the sustainable energy sector and the fact that it is competitive with power from fossil fuels, it is expected that the share of photovoltaic power will continue to grow strongly.

Up to the horizon solar panels that rotate, or hollow mirrors that power steam engines. Such power stations already exist in Europe. Green electrical energy system is the future!

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