M A N U A L SOLAR ASSISTANT “New Generation” The modern experimenting set for energy generation with solar cells Explore - Comprehend – Understand MANUAL SOL-EXPERT group
Solar Assistant “New Generation” Explore - Comprehend – Understand The solar assistant “New Generation” shows the possibilities of photovoltaics in a simple way. In the theoretical part, the topics of sun, photovoltaics in general, energy generation with sun, test criteria, production of solar cells, etc. are explained. The different options, such as island systems and Grid feed-in, are also explained.
Index of content The experiment set Solar-assistant “New Generation” - The experiments Helpful aids - Parts list 4 Construction of the set Assembly motor mounting - assembly solar cell mounting The sun as a source of energy Photovoltaics The principle - The level of effectiveness - The different solar cells The production of solar cells The conversion of light into energy The function - Application examples of photovoltaics 5 6 7 8 9 Parallel systems Feed-in into the public power grid 10 Island sy
The experiment set Solar-assistant “New Generation” The experiment set provides the opportunity to explore the technology and the characteristics of solar cells for power generation in experiments. The target is to emphasize the topic of power generation through solar technology. The solar cells that serve as basis for all experiments consist of monocristalline silicium and are therefore of very high quality. This enables you to conduct the experiments inside without direct sunlight.
Construction of the set Assembly motor mounting Parts list A 1x 1x B 1x 2x A 1 2 B D 1x 3x C 2 A B 3 E 1x H 1x G F C D D H E E D 1x F 1 F 1x Parts list 1x 2x H 2x B D C Assembly solar cell mounting 1x A 1x E F B C 4 H G 5
The sun as source of energy The sun The sun has 333000 times the mass of the earth and the largest energy reservoir of our solar system. With a diameter of 1,392 million kilometres it is more than one hundred times as large as the earth. The average distance from the earth to the sun is 150 million kilometres. Every day, rays of the sun reach us after a travel time of 8 minutes. The light travels a distance of 299792.5 km per second. An incredibly hot gas all and very explosive.
Photovoltaics The principle The conversion of light into electrical energy is called photovoltaics. This term originates from Greek language and is composed of the two words "phos = light" and "Volt - unit of electrical current". Photovoltaics was discovered already in by the French physicist Becquerel. However, the first solar cell was not developed until 100 years later in the Bell-laboratories. This was in the year 1954.
The manufacture of solar cells Material The material that solar cells are made of is quartz sand. It is cleaned of contamination by a special procedure and then processed to a silicium block. Depending on the type of the cell, different procedures are necessary to do this. The Czochralski crystal-pulling process is applied for monocristalline cells. A silicium crystal is dipped into the hot, liquid silicium.
The conversion of light into energy The function The light consists of numerous tiny energy carriers, the photons. If these photons hit the solar cell, electrons are released on the n- layer. The electrons now attempt to wander to the p - layer. This wandering is called the current flow. This always takes place from to +. If a consumer is connected to the solar cell, the wandering of the electron leads through the consumer and drives the motor axis of a motor, for example.
Parallel connection Feed-in into the public power grid Parallel connections serve the purpose of feeding power generated by photovoltaics into the public power grid. Such a parallel connection consists of solar modules, a grid feeder, a main switch and if applicable a recording system for the evaluation of the feed-in data.
Island units 11 Power supply independent from the public power grid Island units are used for places where there is no public power grid available. As it is the case for example in RV´s, boats, or alpine cabins. In order to operate such an island unit one requires solar modules, charger regulators and batteries, and of course also consumers like lamps, radios or the like.
Application examples Examples parallel connection Photos: Copyright www.sunset-solar.
Information about the experiments 13 Notices: Adequate source of light Especially adequate as a source of light is the sunlight. In case of bad weather a desktop lamp with halogenous bulb can be used. The output of this lamp should be approx. 50 - 75 watts. Regarding the halogenous lamp the temperature development must be watched as these lamps can get very hot. ATTENTION: Burning hazard! Distance of the source of light to the solar cell (halogenous lamp) We recommend a safety distance of approx.
Different sources of light... ...and their effects of the solar cell performance Voltage range =2V Current range = 10 / 20 A Not every source of light is adequate for solar technology. The different sources of light that we want to use should have the same distance (approx. 30 cm) to the solar cells. Different sources of light produce different performances in solar cells. The best source of light for photovolatics is sunlight.
Light filters 15 Effects of light filters Voltage range =2V Current range = 10 / 20 A Conventional light filters in solar technology are mainly different conditions of cloudiness. The cloudiness range reaches from “clear sky” to light, medium, up to strong cloudiness Different light spectrums are lost through the filtering of the light. Depending on the foil colour, different light spectrums are filtered out. Therefore the solar cell releases a respectively different performance.
Increase of the voltage through series connection Series connection Voltage range =2V Current range = 10 / 20 A In order to increase the voltage of a solar unit, single solar cells must be connected in series. This is typical for example for standard modules, as they consists of 36 - 40 cells that are connected in series.
Increase of the voltage through parallel connection 17 Parallel connection Voltage range =2V Current range = 10 / 20 A In order to increase the power of a solar module, single solar cells must be connect in parallel. To prove this, we create the following connection. Please pay attention that only solar cells of the same type may be connected in parallel.
The partial shading of solar cells Cell shading Voltage range =2V Current range = 10 / 20 A Partial shading leads to significant performance loss of solar cells. We now want to determine the ratio of the percentual shading to the decrease in performance of the solar cells. Shading in 0 % Shading in 25 % Shading in 50 % Shading in 75 % Shading in 100 % The more a solar cell is shaded, the less power it produces.
The shading of solar cells in series connection 19 Cell shading Voltage range =2V Current range = 10 / 20 A Cell shading in series connection lead to a total performance failure of the system as the shaded solar cell reaches a high inner resistance and thus significantly reduced the power flow. This can be eliminated with the bypass diode! (see also page 20) If a cell is shaded in series connection, the total performance drops to zero.
The shading of solar cells in parallel connection Cell shading Voltage range =2V Current range = 10 / 20 A Partial shading in parallel connection of solar cells lead to a loss of performance, but not to a total performance failure of the system. We will now prove this with an experiment. If a solar cell is shaded in parallel connection, the total performance is reduced by this solar cell performance. = Kroko clamp Only if all solar cells are shaded does the total performance go back to zero.
Tips & tricks 21 1 The szenario: A leaf falls onto a single cell of a solar module. What happens to the total performance of the module? A solar module in a unit network is massively contaminated or there are leaves on it, for example. The solar module now generates significantly less power. This would cause the total performance of the network to be significantly impeded. To avoid this, a bypass diode is built into every solar module.
Horizontal axis movement Horizontal tracking Voltage range =2V Current range = 10 / 20 A This experiment shows that different roof inclines produce different performances of the solar cells. The angle “roof incline” can be read on the side of the solar cell mounting.
Vertical axis movement – Tracking units 23 Vertical tracking Voltage range =2V Current range = 10 / 20 A Is it profitable to track a solar unit vertically to the sun? And how is the ratio angle - performance? An interesting experiment with a spectacular result.
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