Tag Archives: energia solar fotovoltaica

PV Modules Support Structure

Regarding situation of photovoltaic modules, there are the following general possibilities:

Flooring: It is the most usual way of installing modules groups (especially in solar farms) and has great advantages in terms of wind resistance, accessibility and ease assembly.
However, it is more susceptible to being buried by snow, flooding or being broken by animals or people.

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Pole: very used in small dimension systems, if it has a mast. It is the typical assembly type of isolated communication equipment or lampposts feeding.

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Wall: good anchor points must be available on a built building. Accessibility can present some problems.

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Roof: one of the most common because generally enough space is available. It also presents problems of snow cover and risks in roof fasteners waterproofing.

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If system is located in an urban area, most common is to place the module on the roof.

In structure assembly, roof sealing must be ensured by waterproofing elements use.

A study must also be carried out to determine if ceiling will support modules and support structure weight.

However, main factor when fixing the structure is wind strength. Structure must withstand winds of at least 150 km / h.

On terraces or floors, the structure should allow a minimum height of the module of about 30 cm. In mountain areas or where there is abundant snowfall, it must be higher.

The structure and supports should preferably be anodized aluminum, stainless steel or galvanized iron and stainless steel fasteners.

Anodized aluminum is lightweight and highly resistant.

Stainless steel is suitable for very corrosive environments and has a longer useful life but its cost is high.

Galvanized iron structures offer good protection against external corrosive agents with the advantage that zinc is chemically compatible with lime and cement mortar, once these are dry.

Structures come in kits or standard profiles that are on the market and a specific system structure can be built.

Supports designed for a specific solar module are usually cheaper than those manufactured in order to be able to hold any type of module. However, it will surely be the latter that will end up developing in greater numbers in near future.

Normally, a solar modules support has the following characteristics: it has a plate provided on its upper face with quick coupling means for modules and one or more holes for the screws to be introduced and thus join the plate to the support. The support also has fastening means attached to plate lower face for fastening to lower structure.

Orientation will always be towards the equator and the following inclinations are recommended:

Systems with priority function in winter (eg: mountain lodge): 20º higher than place latitude.

Systems with uniform operation throughout the year (p.e .: home electrification): 15º greater than place latitude.

Systems with priority operation in spring and summer (p.e .: campings): same as place latitude.

Systems whose objective is to produce the greatest amount of energy throughout the year (eg: connection to the grid): 85% of place latitude.

The reason for inclination increasing, compared to that recommended for solar thermal collectors, is that generally in the case of photovoltaic systems there is no auxiliary energy system and it is necessary to capture all the energy possible in the most unfavorable period (winter).

Sopelia has developed Solar Layout, the Android App that allows you to obtain the inclination, orientation and distance between rows of photovoltaic modules at the installation site.

This content was extracted from the Solar Photovoltaic Energy Technical-Commercial Manual and is part of Solar e-learning.

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Mexico Solar PV

Mexico is part of the solar belt, an area that considers countries with the highest solar radiation in the world.

The country set itself the goal of generating, by 2024, 35% of electricity with clean energy (currently 80% is generated with hydrocarbons).

It is estimated that solar energy will represent 13% of all energy for next year, and that their participation will gradually grow.

However, solar technology development, as in all Latin American countries (and almost entire world), presents a huge imbalance between large-scale projects and distributed generation.

As far as large-scale projects are concerned, with 37 solar power plants under construction and an estimated investment of US$ 5,000 million, Mexico aims to become a solar power thanks to regulatory support and enviable geographic conditions.

In Coahuila is the largest solar park in Latin America with an investment of US$ 650 million generates about 754 MW.

By the end of 2020, the country will have 5,000 MW of installed capacity.

This impulse is due to the Energy Reform that opened the sector to private initiative, the Energy Transition Law and the three electric auctions held to date.

Average price obtained in the third solar auction (in which contracts were assigned to 9 projects) represented a downward world record for all energies.

In sector, presence of foreign actors stands out, winning approximately 90% of the bids.

The other side of the coin is that of distributed generation.

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Although since 2007 it is possible to install solar panels in homes, shops and industries and connect them to the electricity grid; until 2017, necessary conditions distributed generation development were not created. It represents less than 0.3% of total electricity generation in Mexico.

Before Energy Reform, distributed generation could only be used for self-consumption (and surpluses were lost after 12 months), without it being possible to buy or sell photovoltaic solar energy.

Regulations approved in March 2017 regulate the following compensation models: 1) Net metering; 2) Net billing; 3) Total sale.

In addition, due to ignorance advantages of using solar energy, which could supply a home with high electricity consumption, with only 16 square meters of photovoltaic panels, are lost in Mexico.

Most people are unaware that installing a renewable technology system based on solar panels in their homes is legal, simple and accessible,

Another challenge to face trained personnel lack both technically, to install panels, and engineering, for systems design.

Betting only on large-scale projects is an absurd and non-logical proposal that makes renewables a financial product and not an energy policy tool that promotes employment and technological and industrial development at national level.

It favors macro projects and deepens energy sector convcentration.

Low prices concentration in auctions, with the consequent creation of a dominant position in a few actors (usually foreign companies), will in long term dilute the advantages of low short-term prices.

If we consider auctions as the only tool to increase renewables participation, we will be maintaining an obsolete energy matrix paradigm and committing a very serious error.

The future energy matrix is based on 3 pillars:

1) Energy efficiency

2) Renewable energies

3) Distributed generation

The path of energy revolution and citizen empowerment goes through prosumer figure development and energy cooperativism.

The way of concentration and centralization involves only changing fossils for renewables to maintain the “status quo” for benefit of those who always will continue to act as a collection agency in collusion with political party in government.

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Solar Wiring

Cables, both direct current (DC) and alternating current (AC), if correctly sized, will minimize energy losses and protect the installation.

For a photovoltaic system, DC cables must meet some requirements:

* Have grounding line and protection against short circuit.
* Be resistant to UV rays and adverse weather conditions with a wide range of temperatures (approximately between -40ºC and 110ºC).
* Possess a wide voltage range (more than 2000 V).
* Be simple and easy to manipulate.
* Be non-flammable, of low toxic level in case of fire and without halogens.
* Have a very low conduction loss (up to 1%).

Photovoltaic installation cables must have certain characteristics that differentiate them from conventional cables, although many argue that differences are not very large.

Since voltage in a photovoltaic system is low DC voltage, 12 or 24 V, currents that will flow through the cables are much higher than those in systems with 110 or 220 V AC voltage.

Power amount in Watts produced by the battery or photovoltaic panel is given by the following formula: P = V. I

V = voltage in Volts
I = current in Amperes

This means that to supply a power at 12 V current will be almost 20 times higher than in a 220 V system. It implies that much thicker cables must be attached to prevent overheating or even a fire.

Following table indicates recommended cable section according to power and for different voltage levels.

For very low voltages and low power demands, very thick cables must be used. For example, to reach a power of approximately 1 Kw at 12 V we would need a 25 mm2 section cable. The same as to supply 20 Kw at 220 V.

This increases system price drastically because thicker cables are more expensive.

That is why it is very important that the lengths of DC wiring are as short as possible.

When designing large systems, a cost / performance analysis must be performed to choose most suitable operating voltage. It would be advisable to gather small groups of modules and if possible to make operating voltage higher than 12 or 24 V.

To verify cable section values recommended in tables, maximum voltage drops compared to voltage at which you are working should be below the 3% / 5% limit.

To calculate the relationship between conductor section and its length we can apply following formula:

S = 2 r. l. i / ΔV

Being:

r Conductive material resistivity (0.018 in case of copper conductors)
l Cable section length
i Current intensity
ΔV Voltmeter reading difference

Let’s see an example:

Battery terminals output voltage is 13.1 V. The main line between it and a device, which consumes 60 W, measures 12 m of 6 mm2 cable.

We must find the voltage value at device input to verify that we are within maximum recommended values of voltage drop.

The intensity i = P / V = 60 / 13.1 = 4.6 A

S = 6 = 2. 0.018. 12 4.6 / ΔV

ΔV = 0.33 V

Therefore, voltage at device input will be: 13.1 – 0.33 = 12.8 V

Voltage drop is 2.34% (maximum recommended value: 3%).

It is normal to use tables to select recommended section and use the formula to calculate the voltage drop and perform the verification.

In case that voltage recommended maximum values drop are exceeded, we will select section immediately above and we will carry out verification again.

Cables for photovoltaic applications have a designation, according to regulations, which is composed of a set of letters and numbers, each with a meaning.

Cables designation refers to a series of characteristics (construction materials, nominal voltages, etc.) that facilitate the selection of the most suitable to the need or application.

This is an extract of contents included in Technical-Commercial Photovoltaic Solar Energy Manual and Sopelia e-learning training.

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The Solar Converter

They are equipment capable of altering voltage and characteristics of electric current they receive to transform it into suitable for specific uses.

Those that receive direct current and transform it into direct current with a different voltage are called DC-DC converters. They are not widely used in photovoltaic systems.

Those that receive direct current and transform it into alternating current are called DC-AC converters or inverters. The function of an inverter is to change a DC input voltage to a symmetrical AC output voltage, with the magnitude and frequency desired by user.

They allow to transform 12V or 24V direct current that modules produce and store batteries, in 125V or 220V alternating current.

This allows use of electrical devices designed to work with AC.

A simple inverter consists of an oscillator that controls a transistor, which is used to interrupt incoming current and generate a square wave. This square wave feeds a transformer that softens its shape, making it look like a more sinusoidal wave and producing the necessary output voltaje.

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The voltage output waveforms of an ideal inverter should be sinusoidal.

This gives rise to different types of inverters:

1) Square wave inverters: they are cheaper, but less efficient. They produce too many harmonics that generate interference (noise). They are not suitable for induction motors.

Recommended if you want AC power only for a TV, a computer or a small electrical device. Inverter power will depend on device nominal power (for a 19 ” TV a 200 W inverter is enough).

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2) Modified sine wave inverters: they are more sophisticated and expensive. They use pulse width modulation techniques.

Wave width is modified to bring it as close as possible to a sine wave. Harmonics content is less than in square wave.

They are the ones that offer best quality / price ratio for lighting, television or frequency inverters connection.

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3) Pure sine wave inverters: with a more elaborate electronics, a pure sine wave can be achieved.

Until recently these investors were large, expensive and inefficient; but lately, has been developed equipment with 90% or more efficiency, telecontrol, energy consumption measurement and battery selection.

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Since only induction motors and most sophisticated devices or loads require a pure sine wave form, it is usually preferable to use modified sine wave inverters; which are cheaper.

Inverters must be dimensioned from two variables.

First is considering electrical power wattages that inverter can continuously supply during its normal operation.

Inverters are less efficient when used at a low percentage of their capacity. For this reason it is not advisable to oversize them and they must be chosen with a power as close as possible to that of load consumption.

Second is starting power. Some inverters can supply more than their nominal capacity for short time periods. This capacity is important when using motors or other loads that require 2 to 7 times more power to start than to stay running once they have started (induction motors, high power lamps).

Incorporating an inverter is not always the best option from energy efficiency point of view. It may seem an easy solution to convert all solar system output to a standard AC power but it has several disadvantages.

First is that it increases system cost and complexity.

An inverter also consumes energy (in addition to 15% for performance loss) and therefore decreases overall system efficiency.

For a small house electrification (light points, TV and a small appliance) it is possible and profitable to do without the inverter.

For lighting it is better to invest in low voltage lights instead of investing in an inverter.

Laying of 2 lines can be interesting: one connected to batteries to feed points of low consumption lighting or LED and devices that consume DC and another connected to inverter to power appliances that consume AC.

The advantage of the inverter is that operating voltage is much higher and therefore the use of thick cables can be avoided. Especially when wiring is extremely long it may be economically feasible to use an inverter.

A feature that incorporates most modern converters is possibility of operating as battery chargers, taking alternating current from a generator or grid.

This is an extract of contents included in Technical-Commercial Photovoltaic Solar Energy Manual and Sopelia e-learning training.

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Free Solar Tools (IV)

On Internet we can find free tools for basic or low complexity solar systems dimensioning and for certain components or accessories estimation.

Sopelia research team has carried out an exhaustive search and testing from which a new corporate website section called Free Solar Tools has been created.

Selected tools were classified into 4 categories.

Today we will analyze the fourth of them: Solar Photovoltaic.

In the first category we have already analyzed tools to obtain data about solar resource and other variables to be considered in energy estimation solar system will provide in our location.

In the second category we have analyzed tools to calculate the “load”, ie the energy demand to be met.

In the third category we have analyzed tools for solar thermal systems dimensioning and system accessories estimating.

Now we are going to analyze tools for solar photovoltaic systems dimensioning and to estimate others individual components of a system.

The order of the tools is not random. We have prioritized the most intuitive, the most universal and those that can be used online without download.

For this fourth category our selection is as follows:

1) Solar Calculator

Approximate calculation tool from which budget, production data and system performance study is automatically obtained.

A Navigation Guide and Manuals can be found at page bottom.

Resultado de imagen de sistema solar fotovoltaico

2) Off-grid Solar Systems Calculator

Free online application for off-grid solar systems calculation.

It allows users to introduce new components from any manufacturer and product datasheets to be considered in the calculation.

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3) Off-grid Systems Scale Calculator

Solar basic estimation of off-grid systems. Solar modules, batteries, controller and inverter calculation.

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4) Solar Water Pumping Calculator

Calculator to obtain approximate energy needs figures for solar water pumping.

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5) Solar & Wind Energy Systems Calculation

Tool which determines requirements to meet solar and / or wind contribution for electrification and pumping needs.

Resultado de imagen de sistema eólico solar

6) Grid Connected System Online Simulation

Online application to estimate production and economic income of a grid-connected system.

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7) Battery Bank Capacity Calculator

Calculator to estimate battery bank size needed to keep consumption by solar operation.

Resultado de imagen de banco de baterías solares

8) Wire Section Calculator

Tool in JavaScript format for copper and aluminum DC wire calculation.Resultado de imagen de cable solar

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The Solar Charge Controller

Charge controller is a device located between photovoltaic modules and batteries as an element of an isolated solar system.

Modules output voltage is set some volts higher than voltage battery needs to charge. The reason is to ensure that modules will always be able to charge the battery, even when cell temperature is high and generated voltage decreases.

This causes the drawback that once battery reaches its full charge state, module continues to try to inject energy producing an overload that, if not avoided, can destroy battery.

Charge controller is responsible for extending batteries life protecting them from overload situations, controlling load phases depending on their status and even reaching the cut depending on load needs of them.

Charge controllers may be working in one of the following situations:

Equalization status: equalization of batteries charge, after a period of low charge.

Deep charging state: regulation system allows charging until reaching final load voltage point.

Float state: battery has reached a charge level close to 90% of its capacity.

State of final charge and flotation: regulation system zone of action within Dynamic Flotation Band (range between final load voltage and nominal voltage + 10%).

To know which regulator to incorporate into a photovoltaic system it is necessary to know some elementary parameters.

First, one is isolated solar system nominal voltage. Batteries voltage and photovoltaic solar field define this voltage. Typical values are 12, 24, 48 and up to 60 volts.

The other parameter is photovoltaic modules system load current. It is recommended to multiply short circuit current Isc under standard conditions by 1.25 so that charge controller is always able to withstand current produced by modules.

Known system voltage and determined current value, we can choose the right charge controller. If there are still doubts, we can consult with provider technical department.

The simplest design is one that involves a single stage of control. Charge controller constantly monitors battery voltage but controls charge or discharge, never both. They are the cheapest and the simplest.

This can be achieved by opening the circuit between photovoltaic modules and battery (serial control) or by short-circuiting photovoltaic modules (shunt control).

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In case of controllers that operate in two control stages, the two functions are controlled, both charge and discharge of battery. They are more expensive, but they are the most used.

Current charge controllers introduce microcontrollers and control 3 and up to 4 control stages.

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During last years a new generation of charge controllers has been developed, whose main characteristics are to make photovoltaic field work at maximum working point and to always render it optimally.

These charge controllers are known as power maximizers or MPPT.

Another advantage of these devices compared to conventional controllers is the possibility of working with a different voltage in the generator field (solar panels) and batteries.

This directly influences in being able to put several modules in series, elevating system tension.

Working with lower currents we can reduce considerably voltage drop losses and use smaller cable sections and therefore of lower price.

For the choice of a conventional controller or an MPPT, we have to assess cost overruns that these systems have compared to benefits that it gives us due to system performance increase. In some cases, annual power increase can reach up to 30% compared to conventional controller.

Resultado de imagen de regulador de carga solar MPPT

Charge controller may not be essential in installations where the ratio between modules power and battery capacity is very small (eg: oversized batteries for safety reasons) so that charging current can hardly damage battery.

If modules field power in W is less than 1/100 battery capacity in W / h, charge controller may not be incorporated.

It can also be dispensed with a charge controller if system has self-regulated solar modules (not recommended for extreme climates).

This is an extract of contents included in Technical-Commercial Photovoltaic Solar Energy Manual and Sopelia e-learning training.

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Honduras Solar PV

Honduras is a country where news about massacres, multiple forms of violence, corruption, instability and political intrigues usually comes out and in which two thirds of its 8 million inhabitants live in poverty while the 10% who receive higher salaries, accounting for 42% of national income and poorest 10% only receives 0.17%.

However, there is a sector in which Honduras stands out at regional level: renewable energies and, especially, solar energy.

Honduran government introduced fiscal incentives for photovoltaic installations in 2013.

A tariff supplement for first 300 PV MW that entered into operation before August 1, 2015 was also approved.

In 2015, Honduras and Chile were the largest PV markets in Latin America.

At the end of 2017, total private capital investment for PV plants construction exceeded US$ 1,600 million.

Investment has been divided into 12 solar plants that are already operational and add up to 405 MW; 39% of country’s private sector renewable capacity, amounting to 1,047.07 MW.

In general calculation, 61% of country’s energy comes from renewables, and in 2017 it became the first country in the world with 10% solar energy in its electric mix.

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Most emblematic project is Nacaome-Valle Solar Park, which generates the energy consumed by some 150,000 Honduran families every day.

It has 480,480 modules with capacity to produce up to 125 MW of alternating current (AC) peak power.

It took more than 1,000 material containers, US$ 240 million in investment and the help of more than 1,200 employees who changed shifts without stopping, to build and start operating the plant in less than 2 years.

Photovoltaic modules receive the radiation to generate between 600 and 850 V, in CC form. With use of inverters, this energy is converted into AC, which passes through transformers to raise its Voltage to 34.5 kV and distribute it around the park.

Finally, this current is transmitted to plant electrical substation, where voltage rises to 230 kV to be transmitted throughout the country by Central American Electric Network, which arrives from El Salvador, passes through Honduras and goes to Nicaragua. .

The Nacaome solar plant has been an engine of economic, scientific and academic development for Honduras people and a monumental engineering work that has put Central American nation on sustainable energy industry international map.

Imagen relacionada

Construction of Los Prados solar park, which would have 53 MW and should have started operations at end of 2016, is being halted by local residents protests who fear possible damage to their people caused by the park.

A solution is currently being sought between authorities and settlers, since everything is ready for work execution, but news is not encouraging.

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Haití Solar PV

Although slow, Haiti’s economic and social recovery appears to have begun and to give a strong boost to renewable energy sources, particularly photovoltaics, has been a wise decision.

First important signal has come through a humanitarian organization, whose mission is to modernize health in the world, which has opened with the Haitian Ministry of Health, the world’s largest solar powered hospital.

Facilities receive the contribution of 1,800 photovoltaic modules installed in the roof that enable medical attention of more than 60,000 people.

Resultado de imagen de hospital solar haití

Second signal is called Klere Ayiti or Light Up Haití.

It is a joint project between a money transfer company and Arc Finance, in which also collaborates the Agency for International Development (USAID) and the Inter-American Development Bank (IDB).

It´s a service through which people can buy and send photovoltaic kits to their relatives on the island.

Each solar kit includes 2 or 3 LED lights, solar module charger, and various plugs with which cell phones can also be charged.

The lights can be used as flashlights or hanging from the ceiling and kits cost US $ 140 and US $ 180, respectively.

The project organizers chose the kit model from 25 different manufacturers evaluated over a period of 2 years.

It´s a product that gives families the possibility of having light at night, something we take for granted in developed world and that implies a radical progress for these people.

Resultado de imagen de light up haití

Third signal materialized in February 2016 in the mythical Champ de Mars square in Port-au-Prince, the capital of Haiti, where the Presidential Palace is located.

The square has since then a lithium-ion energy storage system powered by 110 kW of solar modules to provide light and Wi-fi in this public area.

Resultado de imagen de energía solar haití

Fourth signal is called the “Triumphe” project and is the first photovoltaic plant in Haiti.

The system has an installed capacity of 100 kW configured so that contribution coincides with the daily demand of 200 kWh.

The ‘Triumphe’ project will assess the potential of similar applications to support renewable energy in Haiti.

Project was launched thanks to Haitian Government and World Bank Energy Office financing and is a symbol in renewable energy generation.

But above all it represents Haiti’s continuous efforts to recover from 2010 earthquake that destroyed a large strip of the capital and its environs, which affected around 3 million people.

Renewable energy systems such as Triumphe represent a sustainable means to address persistent poverty and lack of basic public services in the country, including energy access, water and support for socio-economic development tools such as wireless internet access.

Resultado de imagen de solar fotovoltaica haití

Haiti, with a population of 10,123,787 inhabitants and a poverty rate of 77%, is considered one of the poorest countries in the world.

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The Solar Battery

Without batteries, off-grid PV systems (except some cases such as water pumping) would be meaningless, because their functionality depends on electrical energy storage.

The battery is an electrochemical device that transforms chemical energy into electrical energy, whose presence is necessary because solar modules only generate energy when light hits them.

In addition, sometimes battery provides an instantaneous power higher than that of modules (eg: for starting motors) and provides stable and constant voltage regardless of light incidence.

The battery determines modules operating voltage. Therefore a safety margin is required which will mean a small loss (about 10%) with respect to maximum power that module could provide at higher voltages.

There is no ideal battery. The choice is a compromise between economy and suitability starting from a minimum quality that provides reliability and long life to the system.

In a battery, we have to take into account 3 technical considerations:

1º The discharge capacity

It is the maximum amount of electrical energy that can be supplied from its full charge to its complete discharge. Measurement unit is the amp hour.

The loading and unloading ratio and the battery and environment temperature are factors that can make vary its capacity.

Resultado de imagen de capacidad batería solar

2º The discharge depth

In renewable energy systems, only deep discharge batteries are used (we refer to capacity percentage that is used in a cycle of loading and unloading).

Deep discharge batteries have an average discharge of 25%, and can reach 90%.

Resultado de imagen de capacidad batería solar

3” Cycles of a battery

It is the time from complete charge to discharge.

Battery life is measured in number of cycles it can handle.

Resultado de imagen de capacidad batería solar

Auto-discharge should also be considered as an additional consumption that daily demands a certain percentage of stored energy.

As damaging as excessive discharge is for a battery to too much load. Way to prevent this is by introducing a charge controller.

Every time battery is recharged, does not completely regenerate, resulting in a degradation that will determine battery life.

If discharge depths are respected and maintenance is correct, battery service life should be approximately 10 years.

For PV systems, batteries used are:

1. Lead-Acid: Characterized by their low cost and maintenance they require (need to be in a cool place and periodically check electrolyte amount).

Lead-antimony are the most used in medium and large systems and lead-calcium are mainly used in small systems.

There are also 2 types of sealed lead-acid batteries: Gelled (incorporating an electrolyte gel type) and Absorbed Electrolyte (electrolyte is absorbed into a microporous glass fiber or a polymer fiber web).

These batteries don´t require maintenance in water aggregate form nor develop gases, but both require less deep discharges during their service life.

Resultado de imagen de batería solar de plomo - ácido

2. Nickel-cadmium: offer better performance, but have a higher price.

The electrolyte they use is an alkaline, have a low self-discharge coefficient, good performance at extreme temperatures and the discharge they support is around 90% of their rated capacity.

They are recommended for isolated or dangerous access places.

They can´t be tested with same reliability as lead acid. Therefore, if it is necessary to control charge state, they aren´t the best option.

Resultado de imagen de batería solar de níquel - cadmio

3. Lithium: they take up little space, they weigh less, they do not emit gases, they can be put anywhere, loading time is the fastest, total discharges can be made without affecting their useful life in a relevant way.

What is the disadvantage? Its very high price.

The manufacturer who can optimize them will have found the solar sector Holy Grail.

Resultado de imagen de batería solar de litio

This is an extract of contents included in Technical-Commercial Photovoltaic Solar Energy Manual and Sopelia e-learning training.

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The Solar Module

Cells are silicon in the most used modules, element which is the main component of the silica, the material of the sand.

The regional production capacity distribution differs significantly depending on product type and its value chain position.

Solar grade silicon production capacity is headed by the US; followed by Europe, China, Japan and the rest of Asia.

Silicon cells and modules production capacity is dominated by Chinese and Taiwanese manufacturers; followed by Europeans, Japanese and the US.

Thin-film manufacturers must still optimize production to reach optimal cost structure to be competitive.

A difficult task with much lower prices for polysilicon, resulting in a significant decrease in silicon modules prices.

Resultado de imagen de fabricación panle solar

In order to avoid scarcity or oversupply cases, it is of utmost importance to guarantee supply, demand stability, based on a sustainable market so that the industry can foresee the growth of the same and plan its capacities.

Photovoltaic systems demand depends to a large extent on general economic climate and, most importantly, on governments policies to support their development.

Tariffs, along with administrative procedures and grid connection simplification, as well as priority grid access are policies aimed to guaranteeing sustainable demand.

A silicon cell provides a voltage of about 0.5 V and a maximum power of between 1 and 2 W.

In module manufacturing process, a certain number of cells must be in series connected to produce voltages of 6, 12 or 24 V indicated for most applications.

To produce a 12 V module, you need between 30 and 40 cells.

Cells connecting process is done by a special welding that joins the back of a cell with the front face of the adjacent one.

After electrical interconnections are completed, cells are encapsulated in a sandwich structure (tempered glass laminate – EVA – EVA – polymer cells).

The structure varies by manufacturer.

Subsequently a vacuum sealing is carried out, introducing it in a special furnace for its lamination, making tight the assembly.

If they have a metallic support frame, module perimeter is first surrounded with neoprene or some other material that protects it.

Resultado de imagen de silicio solar

Once positive and negative connections are mounted, following controls are performed to ensure a 20-year service life with acceptable performance levels:

– Thermal cycles (-40 ° to 90 ° C)
– Humidity cycles.
– Freezing cycles.
– Wind resistance.
– Mechanical strength.
– High electric shock resistance.
– Saline atmosphere test (for marine environments).

Manufacture, performance, electrical and mechanical characteristics of photovoltaic module are determined in product technical specifications provided by the manufacturer.

As in solar cell, following parameters are important:

– Module maximum power or peak power PmaxG.
– IPmax: Intensity when power is maximum or current at maximum power point.
– VPmax: voltage when power is also maximum or voltage at maximum power point.

Other parameters are:

– IscG short-circuit current.
– Open circuit voltage VocG.

These parameters are obtained under standard conditions of universal use according to EN61215. Established as follows and the manufacturer must specify:

* Irradiance: 1000 W / m2 (1 Kw / m2)
* Incident radiation spectral distribution: AM 1.5 (air mass)
* Normal incidence
* Cell temperature: 25ºC

Modules working conditions may be very different once installed, so it is advisable to know variations that can occur, in order to make calculations relevant corrections.

In practice, module power decreases by approximately 0.5% for each cell temperature increase degree cell above 25 ° C.

To avoid having to calculate radiation average intensities, we can assume that cell average working temperature is 20º higher than ambient temperature.

For this concept, yield drops to 90%. In not based on crystalline silicon technologies, yield lower is smaller.

This is an extract of contents included in Technical-Commercial Photovoltaic Solar Energy Manual and Sopelia e-learning training .

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