Thermal Solar Collector

Thermal solar collector is responsible for capturing solar radiation and converting its energy into heat energy.

A body exposed to the sun receives an energy flow Er and heats up.

Simultaneously, thermal losses occur due to radiation, convection and conduction, which grow as the body temperature increases.

There comes a time when thermal losses Ep equals the gains due to the incident energy flow, reaching the so-called equilibrium temperature:

 Er = Ep

The equilibrium temperature of the collectors is usually between 100º and 150º C under normal conditions of use and for irradiation values in the order of 1,000 W / m2.

If it is possible to continuously extract a part of the heat produced Ee to take advantage of it as usable energy, the equilibrium conditions change:

Er = Ep + Ee

Ep is now smaller because a part of the energy received Er is tapped Ee.

The body has become a solar thermal collector.

If we want to increase Ee we have two options: reduce thermal losses Ep or increase energy flow Er.

First option involves collector design and construction improving in order to reduce losses.

For the second option is used the concentration technique, which by some optical system concentrates the solar flux on a smaller surface so that as the area decreases, the intensity increases.

In a solar collector the energy is extracted through a fluid called heat carrier.

Resultado de imagen de rendimiento colector solar térmico

The greater the difference between operating temperature and ambient temperature, the greater the thermal losses and thus the lower energy amount that heat transfer fluid will be able to extract.

The collectors must be operated at the lowest possible temperature, provided that temperature is sufficient for the specific use in each case.

This is because collector efficiency decreases as the operating temperature increases.

Improved insulation helps thermal losses reduce.

Reflection losses are due to transparent cover that usually exists in almost all collectors.

It will be necessary to properly orient the collectors so that they receive the greatest radiation amount possible during the period of use.

The question: which is the best collector ?

A priori has no answer.

It will depend on system location and energy demand that is intended to be met.

There are many types of solar collectors, but there are two large groups: unconcentrated collectors and concentrated collectors.

Solar thermal collectors according to their working temperature:

1) Low temperatura

1.1) Flate: protected and not protected

1.2) Vacuum tubes: direct flow, heat pipe and solar concentrator CPC)

2) High temperatura

2.1) Parabolic Cylinder

2.2) Central receiver system

2.3) Parabolic disks

2.4) Solar chimney

3) Other collectors

3.1) Rubber

3.2) Spherical

3.3) Conical

Resultado de imagen de colector solar térmico de baja temperatura

In next posts we will analyze in detail each collector type.

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

Solar energy wherever you are with Sopelia.

El Salvador Solar PV

Until recently there were only off-grid PV systems and a limited number of on-grid systems for self-consumption in El Salvador; most of them in government buildings, schools and universities.

By the end of 2015 the largest PV system in operation was 99 kW.

In October of that year AES Moncagua PV plant, with an investment of US$ 4 million and 2.5 MW, was inaugurated.

Resultado de imagen de fotovoltaica aes moncagua

This solar plant located in San Miguel is directly connected to Electric Company of East (EEO) distribution network for later supply.

At present, it is under construction that will be the largest solar power generation plant in the country, with 100 MW of installed capacity.

It will be located in Rosario de La Paz, La Paz department, in an area of 150 blocks, a few kilometers from Monsignor Óscar Arnulfo Romero International Airport.

The project, totaling US$ 151 million, will be financed by an IDB loan of US$ 57.7 million, a co-loan from the Canadian Private Sector Climate Fund of the Americas of US$ 30 million and co-loan of a French Development Agency subsidiary of US $ 30 million.

The winning company Providencia Solar S.A. de C.V., a company incorporated in El Salvador for the sole purpose of the project developing, is owned by an independent French renewable energy producer.

At the end of June 2016 the first solar module was installed and construction began.

Initial forecasts estimate that it will be injecting power in April 2017 after 11 months of construction and an additional test perform month.

Resultado de imagen de providencia solar s.a. de c.v

Solar Reserve and La Trinidad projects (also of 2014 bid) would add 28 MW.

During January 2017, another 169.9 MW of renewable energy were awarded, of which 50 MW will be from wind energy and 119.9 MW from photovoltaic generation.

There were 29 proposals (4 of wind generation and the rest of photovoltaic).

The offers were in response to a tender launched by the country for 170 MW of renewable energy (initially 100 MW of solar and 70 MW of wind).

The bidding rules leave a construction period of 3 years for wind projects and 2 years for solar.

Tomorrow 25th of January will be official notification date and contracts will be signed between January 31st and March 27th.

There were 4 solar winning proposals for this tender.

A company combining French and Salvadoran capital was awarded 50 MW at a unit price of US$ 49.55 / MWh and another 50 MW at US$ 49.56 / MWh. The solar plant, with an estimated investment of US$ 150 million, will be located in Ozatlán, Usulután.

In addition, 10 MW of solar generation were awarded to an offer at US$ 67.24 / MWh and 9.9 MW to another offer at US$ 54.98 / MWh.

Allocation to solar projects exceeded the 100 MW expected because wind energy supply offers did not reach the initially installed capacity required.

Solar energy wherever you are with Sopelia.

Free Solar Tools (II)

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 second one: Consumption Calculation.

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

Now we are going to analyze tools to calculate the “load”, that is, the energy demand to be satisfied.

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

For this second category our selection is as follows:

1) Housing heating calculation

Approximate calculation tool developed by the Ministry of Industry, Energy and Mining of Uruguay.

Consider the variables surface, heating technology, materials, openings, insulation and roof.

Data that interests us to solar thermal system dimensioning is kcal / month.

Imagen relacionada

2) Advanced Energy Efficiency Calculator

Tool to make detailed calculations of house energy consumption.

It includes a general table (all devices), a groups table (device families) and a configurable table (custom).

Last one is a version in which you can modify table data and know more accurately your particular case.

Resultado de imagen de electrocalculator

3) Hot water, heating and pool conditioning demand calculation

Spreadsheet for hot water, heating and swimming pool conditioning demand estimation.

Only Spain localizations are deployed, but can be used as template and adapt to any location by manually solar resource and other starting data entering.

Inputs: location, number of occupants and occupant’s consumption, temperature of use, collector’s number.

Outputs: collector surface, inclination, accumulation volume, yields and savings, demand and coverage calculation and comparative graphs.

Resultado de imagen de demanda ACS, calefacción y piscina

4) Electrical consumption calculation

Only available for PC.

Cannot be viewed from mobile devices (Smartphone / Tablet).

Application developed by the Ministry of Energy and Mines of Peru to estimate electricity consumption based on each device power (W) and hours of use number.

Resultado de imagen de Ministerio de Energía y Minas de Perú

5) Energy consumption calculator

Very easy operation online free basic calculator.

Different electrical devices, their power, and their daily use regime are added.

Resultado de imagen de calculadora de consumo eléctrico

Accessing Free Solar Tools section of Sopelia’s corporate website you will find the links to have these tools and begin to configure your future solar system.

Solar energy wherever you are with Sopelia.

2017: The Year In Which Argentina Made Renovable

The year 2017 in Argentina is the break point between a disastrous past and a future that can be plentiful in renewable energies field.

In RenovAr Program rounds 1 and 1.5, 2,423 MW of renewable energy projects have been awarded.

The always old-timers will say (and in some cases with reason) that many projects will not be realized.

The surprisingly low award prices and the increase in financing costs provoked by the white house tenant change make doubtful some projects profitability.

Especially the 60% that was not developed by Chinese origin promoters. The latter have the handicap of unattainable financing for the rest, but they will also have difficulty coping with the high “Argentine cost”.

The truth is that much of them will become reality and renewable energy participation in the country’s energy matrix will begin to be relevant (Law 27.191 objectives of 8% in 2017 and 20% in 2025).

Resultado de imagen de solar térmica argentina

On distributed generation side, the impulse is given by solar thermal energy, which in locations without natural gas network access is already more profitable than all other energy sources.

In addition, those who are developing new constructions in locations with natural gas network access and do not incorporate solar thermal energy in their projects, are making a serious mistake.

Energy tariffs will continue with their irreversible sincerity process.

Photovoltaic distributed generation is more difficult because involves a more important initial investment and a longer repayment term.

In locations with electricity grid access is being developed almost exclusively for lighting applications in complement with LED technology.

In isolated locations for houses electrification, water pumping, signaling and communications.

This situation is going to change throughout this year.

Decree 531 establishes the purchase mechanisms (private contracting, self-generation or cogeneration or participation in a joint purchasing mechanism) for users with energy demands equal to or greater than 300 kW; which must cover at least 8% of the total electricity consumption from renewable sources by December 31, 2017.

Sopelia is advising many companies that have already taken the first step: develop solar energy projects on the paper to evaluate purchase mechanisms versus self-generation in order to achieve (and even surpass) the required percentage.

Solar is the renewable energy with urban environment integration highest level and these companies can take advantage of their roofs to place photovoltaic or thermal systems.

Resultado de imagen de solar fotovoltaica argentina

All companies that make intensive electrical energy use or include fluids heating in their production process should elaborate these projects on paper to make the right decisions with real information that accurately reflects their particular situation.

The government could accelerate this transformation process by:

* Regulations that oblige solar thermal systems incorporation in all new construction, in Spanish CTE style

* Implementation of a serious plan (installed capacity objectives, deadlines and compliance measures of those objectives, measures to correct deviations) that really favors the distributed photovoltaic generation development in residential, commercial, services and industrial sectors

* Impulse of interconnection infrastructure investment by energy distribution companies

* Conducting a thorough study to reduce import tariffs on renewable inputs and equipment that can hardly be manufactured in short and medium term in the country.

Renewable energies put Argentina in front of another opportunity (and go …) to end its sad paradox:

Having enormous natural resources and never making a correct use of them for benefit of all its citizens.

Solar energy wherever you are with Sopelia.