What Is Solar Energy?

If we can leave behind the public wave of denial in the reality of climate change and global warming, as caused by us, people, solar will be increasingly important in future lives as a clean, renewable energy.
Energy from the sun is present in fossil fuels, stored in fossilised plant remains that once grew and absorbed the sun’s energy through photosynthesis.

It is also directly experienced in the warmth of the sun and in its light.

The history of solar energy is a long one indeed. Defining solar energy may be simple but there is not just one answer to the question: what is solar energy? Generally solar energy is divided into two types: thermal energy and electric energy.

In summary, what is solar energy? It is

1. Energy from the sun

2. Thermal energy

3. Electric energy

4. Stand-alone

5. Grid connected

SOLAR HOME ENERGY BASICS

Solar water heating, Solar PV electricity and Solar space heating are the three major solar technologies.

Solar Technologies

Current solar technologies involve 3 major areas (and a rather marginal one connected to space cooling):

1) Solar water heating
2) PV (photovoltaic) electric solar (electricity production for residential and commercial uses, and also for Recreational Vehicles (RV), Outdoor lighting, etc.).
3) Solar space heating
4) Solar home space cooling.

PV On-Grid And Stand-Alone Systems

Most PV solar systems are on-grid systems. See, for details: On-grid Solar and wind systems.

A stand alone PV energy system is not connected to a wider public or private grid. In this case it responds only to the needs of its owner. The stand alone systems is typicallu more expensive due to the required set of batteries for storing the energy.

Stand-alone PV solutions are popular in remote areas, where the connection to electric grids is expensive or impossible.

SOLAR ELECTRICITY: HOME PV - PHOTOVOLTAIC

Solar modules are the core of any Solar PV system, and are based on solar (photovoltaic) cells, which are made of special materials called semiconductors, usually silicon.
PV Solar Modules: The Sizing Problem

Solar modules collect the sun's energy and convert it into electricity. The number of modules (connected to form a rooftop array) will depend on your needs, climate and on the modules wattage.
PV Home And Non-Home Uses

Photovoltaic (PV) cells are used to produce electricity for residential use and also in calculators, watches, parking meters, and Vans, Boats and Recreational Vehicles...

Concentrating Collectors

Concentrating collectors are a rather marginal option in the solar market. They use parabolic and mirrored surfaces to concentrate and get sunlight energy. They are able to generate very high temperatures, and are mainly used on commercial applications. They demand direct sunlight and do not perform well in climates with low levels of direct sunlight.

They are scarcely used on residential applications. They are expensive and involve a large set of demanding requirements and configurations. They are used in large projects and electrical generation. The true alternative concerning solar panels for residential applications is between flat-plate and evacuated-tubes solar collectors.

Evacuated Tube Collectors

Evacuated tube collectors are a more recent technology than that of flat-plate collectors, and a more promising one. This type of solar collectors can be used in most climates and applications, but despite recent decreases on prices, they still are more expensive than the average flat-panels.

They are the best solution for demanding applications, that is, applications demanding higher water temperatures.

Solar Liquid Flat Glazed Collectors

These panels can be used in solar domestic water heating systems and for central heating (integrated in systems involving forced air systems, radiators or radiant heating). They are a flexible, tested and competitive option. They are by large, at present, the most common type of collectors in moderate and sunny climates.