Solar energy is the energy obtained by capturing light and heat emitted by the sun.

Radiation power varies by time of day, weather conditions and latitude.

It can be assumed that a good surface radiation value is about 1000 W / m².

This power is known as irradiance.

Radiation is usable in direct and diffuse way, or the sum of both components.

Direct radiation comes directly from the solar focus, without intermediate reflections or refractions.

The diffuse is issued by the daytime sky thanks to the multiple reflection and solar refraction phenomena of the atmosphere, clouds and other atmospheric and terrestrial elements.

Direct radiation can be reflected and concentrated for use, while it is not possible to concentrate the diffused radiation coming from all directions.

Albedo radiation is reflected by the bodies located around the surface on which we want to assess the radiation.

The amount of energy due to sunlight direct radiation an exposed surface can intercept depends on the angle between the ray and the surface in question.

If the surface is perpendicular to the rays, this value is maximum, decreasing as the angle does.

The intensity on the surface varies in the same proportion as energy does.

This tilt effect is the reason why sunlight heat much more up at noon than in early morning or late afternoon.

It is also the reason why high-latitude regions (near the poles) received much less energy than the closest to Ecuador.

Solar coordinates used to determine Sun position referred to the horizontal plane are two:

• Solar Height (h) which is the angle between the sun’s rays on the horizontal surface. The zenith angle is the rays angle with the vertical, that is, the complement of the height.

Solar height (northern hemisphere perspective)

• Azimuth (A) which is the Sun angle rotation measured on the horizontal plane through the ray projection on said plane and taking as origin the North if we are in the southern hemisphere.

By convention, the azimuth is considered negative when the sun is to the east (morning) and positive when placed to the west (after noon).

Azimuth

The theoretical number of sunshine hours is time length between sunrise and sunset.

In these 2 times the height of the sun is zero.

The number of sunlight hours depends on the geographical point considered and the time of year.

During the summer, the sun makes a very wide and high trajectory on the sky and is long over the horizon. The opposite happens in winter.

Path of the sun in different seasons (southern hemisphere perspective)

At solar noon (instant when the azimuth is zero), the sun elevation is maximum and shadows length minimun.

The shadow on the floor of a vertical rod coincide with meridian (South-North) direction, which must be accurately determined, for example, to correctly orient solar collectors or modules.

The most important factor influencing the amount of incident solar energy on a location or particular area is cloudy days ratio that occur each year.

This content is extracted from “Introduction to Solar Energy” ebook sold exclusively at Amazon.

Solar energy wherever you are with Sopelia.

In September 2014 we sent to General Pueyrredón Municipality government in Argentina a draft with proposals.

It was proposed energy efficiency and increased use, promotion and development of solar energy at municipal level.

We believe it can serve as reference for those municipalities that are not using their solar resource and want to start doing so.

The proposals include the following assumptions / premises:

I) Economic evaluation (initial investment, annual savings and investment recovery period) of energy efficiency measures to be applied and solar energy systems to incorporate.

II) Energy efficiency and solar energy promotion to improve environmental quality, develop a new economic sector and new jobs creation in the Municipality.

III) Academic, business and institutional sectors participation.

1.1) Energy Efficiency Proposals

1.1.1.) Public buildings audit to identify areas in which implement energy efficiency measures.

1.1.2) Public buildings whose roofs can be used to install solar thermal collectors and photovoltaic modules relieving.

1.1.3) Facilities with intensive lighting use (more than 8 hours / day) relieving to evaluate luminaire replacement by LED, which can achieve savings ranging from 50% -80%. Evaluate motion detectors installation in transit areas and other lighting devices optimization measures.

1.1.4) Evaluate replacement of boilers and air conditioners equipment by biomass, solar thermal and heat pumps, which can achieve between 40% -60% savings.

1.1.5) Installing saving systems (aerators, valves, low consumption taps, etc.) and water reuse (rainwater recovery, rainwater infiltration, etc.) in public buildings and encourage its use in private sector.

2.1) Solar Thermal Energy Proposals

2.1.1) Use of solar thermal energy compact equipment to provide hot water to houses in social housing programs and new developments.

2.1.2) Use of solar thermal collectors (flat and vacuum tube) with heat transfer fluids, heat exchangers and independent accumulation tanks; to obtain hot water in public buildings and municipal pools conditioning.

2.1.3) Use of solar thermal systems for new construction public buildings and facilities conditioning.

3.1) Solar PV Energy Proposals

3.1.1) Use of solar photovoltaic systems for lighting and electrification of schools, medical centers, police stations and residential users in isolated localizations. 50W to 400W systems.

3.1.2) Implementation of photovoltaic solar energy in signs (sea, rail, road and air) and parking meters renovation or modernization.

3.1.3) Assess solar photovoltaic energy incorporation in OSSE and other municipality’s departments for:

– Water supply
– Water pumping / irrigation
– Cathodic protection
– Remote satellite systems, fire detection, telemetry and other systems that must provide services in remote or inaccessible places.

20W-50W (emergency kits), 100W-400W (repeaters) and more than 20 Kw (block valves).

3.1.4) Street lighting. Solar lamp with led proof in place to designate (industrial park, municipal office, etc.)

3.1.5) Photovoltaic grid connection project presentation for programs like GENREN (Ministry of Energy).

4) Long Term Policies

Municipality proposals within Emerging and Sustainable Cities Initiative framework.

4.1) Training

4.1.1) Renewable energies training activities development aimed at agents involved, whether installers, designers, professionals or companies; as it is one of the decisive factors linked to the continuous technology development.

4.2) Urban and Public Facilities

4.2.1) Implement the evaluation of solar technology architectural integration potential in facades and solar passive architecture principles application in new construction public buildings.

4.2.2) Provide treatment to solar ordinance proposal jointly presented by Puerto Hueche S.R.L. and the Clean Energy Research Group, UNMDP Law Faculty.

4.2.3) Public Lighting. Implementing solar and solar / wind street lighting utilization evaluation in all new developments making in each case the comparison with grid-connected conventional lighting system complete work needed.

4.3) Industry

4.3.1) Assess solar thermal energy equipment manufacturing feasibility in Municipality territory, considering that in Industrial Park related equipment manufacturers (heating and cooling) already exist.

4.3.2) Assess PV kits and PV lighting devices mounting feasibility. Synergy with UNMDP (Engineering Materials).

4.3.3) Promote the use of solar thermal energy in industrial sectors with practical applications:

* Brewing and malt
* Textile industry
* Liquid baths automotive paint cleaning and degreasing
* Food industry
– Hot water production for bottles cleaning and disinfecting
– Meat products, canned vegetables and canned fish washing, cooking, blanching and cleaning
– Canned sterilization
– Animal slaughter facilities cleaning.

And in service sector. Some examples:

– Hotels
– Urban waste collection and treatment
– Supermarkets and hypermarkets
– Laundry, carpets cleaning, upholstery, dry cleaners, etc.
– Car repair garages
– Glass containers recovery and reuse.

Solar energy development policies implementation with Sopelia.

Sergio came to potential client Mary´s home and asked to see the roof where the solar installations would be located.

Once up, Sergio began to manipulate his mobile phone.

“Do not bother,” Said Mary … “there is no coverage.”

This did not stop Sergio because his tool works based on the location of the mobile device through GPS positioning (internet connection is not required).

From location latitude all calculations are performed.

Sergio selected Solar Thermal Energy from Installation Type Menu first.

Then he confirmed the location on the Map and selected Heating from Installation Use Menu.

The inclination angle of the thermal collectors depends on the use of solar equipment.

Sergio query his mobile, getting the result and informs Mary that 50◦ is the optimal solar thermal collector’s inclination.

Mary, a little surprised, asked what would be the optimum orientation.

“The optimum orientation of the solar collectors is towards the Ecuador” tells Sergio.

For guidance, Sergio used Compass App recommended by his tool that has cautiously already downloaded in his mobile.

The last missing data: separation between thermal collector’s rows.

Because surface was horizontal, only data needed was solar collector height in cm.

Sergio query his mobile, get the result and tells Mary that 4.42 m is the minimum spacing between rows.

Totally surprised, Mary tells Sergio where the solar photovoltaic installation would be located.

Sergio selected Solar Photovoltaic Energy option in the Installation Type Menu now.

Then he confirmed the location on the Map and selected On-Grid Connection from Installation Use Menu.

Sergio query his mobile, get the result and tells Mary that 34▫ is the optimum inclination for photovoltaic installation.

As in this case the module rows would be placed on a non horizontal surface, Sergio consulted Mary inclination of that roof sector, which is 20◦.

Sergio entered deck inclination angle from horizontal with a positive value because cover inclination direction coincides with modules inclination.

Finally Sergio told Mary numerous Tips available at i App button to consider for collection surface setting.

Sergio made a very good impression on Mary and demonstrated professionalism.

This App exists, was developed by Sopelia R+D+I and its name is Solar Layout.

Mary´s satisfaction was complete when Sergio told her how could download Solar Layout on his mobile and, in a very intuitive way, get herself recommended values at any geographic location.