Sunday, October 10, 2010

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.

Solar Air-Flat Glazed Panels

Solar air-flat glazed collectors are mainly used in solar space heating, and may be tied to forced air systems. They have some advantages over solar liquid-flat panels (they produce heat earlier and later in the day than liquid systems, they do not freeze and the negative consequences of eventual leaks are minimal) but they are also less efficient than liquid collectors, and aren’t as flexible in their applications.

Solar Flat Unglazed Panels

Solar-flat-unglazed collectors are used in swimming pools and simple house space heating (typically, solar air heaters with no heat storage, designed just to heat a room or a small part of the house). Unglazed panels are used in applications demanding low temperatures. They have a wide range of applications in sunny climates, where they can replace more expensive solar collectors.

Solar Collectors Choice

There are two main types of solar heating collectors:

- flat collectors (glazed and unglazed);
- evacuated-tubes collectors

Other types of solar collectors comprise: ICS (Integrated Solar) and concentrating panels. These last panels are rarely used in solar home applications.

Choosing the type of collector depends largely on climate conditions, price and on the type of application. Below we draw some some rough conclusions about the most suitable solar panels for several solar applications, taking into account the climate, price and type of application.

Solar Modules

Solar electricity involves a specific type of solar panels (mono crystalline, polycrystalline, thin film…) typically manufactured by large manufacturers as Sharp, Kyocera, Photowatt, BP Solar, or Mitsubishi...

SOLAR COLLECTORS AND SOLAR MODULES

The term solar solar collector refers to solar panels for hot water and air heating requirements. The type of solar collectors vary with the intended goal – water heating, radiant floor heating, pool heating, air space heating - and the climate where they are going to be applied.

Solar modules (also referred to as PV modules and solar generators) are used to convert sunlight directly into electricity.

Drainback Solar Systems

Like anti-freezing systems, drainback solar systems are also specially conceived for cold climates. They offer lower maintenance and longer life and reliability, but they pose higher demands in terms of design.

Antifreezing Solar Heating Systems (Active-Closed Pressurized Systems)

Cold climates demand more complex systems. Batch/ICS systems are clearly inadequate in freezing conditions, and thermosyphon solar systems involve some limitations.

One of the most popular solutions for freezing climates comprises a relatively complex system with an antifreezing fluid (glycol, usually), a differential controller, an expansion and a storage tank, and a heat exchanger and sensors and valves.

The Open-Loop Direct System

If you live in a moderate or hot climate, without freezing problems, you may choose a simple solar heating water system using a pump and water at the collector level. This system is called technically an Open-loop direct system.

Thermosyphon Solar Systems

Thermosyphon systems are also a simple solar heaters, very efficient and very popular in moderate and hot climates. They are cheap and demand no pumps or special controls, and can also be installed in colder climates.

Batch ICS Solar Systems


Batch solar systems (or ICS) are the simplest and, in a way, the oldest solar heating systems. They haven’t pumps, separated storage tanks or anti-freezing. They combine a solar collector and a storage tank into one single unit, and in their most simple version they are a mere water tank within a glazed box.

SOLAR HOT WATER HEATERS: THE DESIGNS

The designs and the type of components of the solar water heaters vary a lot. But we may consider five main designs, with different costs and complexities.
Solar Water Heating Designs
Main solar water heating designs:

- the batch ICS solar systems (an ultra-simple system for moderate climates);
- the thermosyphon solar systems (for moderate and other climates);
- the solar open-active heating systems (for moderate and hot climates);
- the drainback systems (cold climates);
- the anti-freezing pressurized systems (cold climates).

PORTABLE SOLAR ENERGY POWER STATIONS

Many families have already started using solar energy to power their homes. Portable solar energy power stations have many practical uses. Today there actually are portable solar energy power stations. Most portable solar power units use photovoltaic panels (PV panels). These portable solar energy stations generate energy from sunlight.

Advantages of using solar collectors

The major advantage of solar collectors - simplicity and relative cheapness of manufacture, ruggedness in operation.

The only important point - please be aware that on a hot sunny day with no parsing water can overheat above the boiling point, so the design must take appropriate precautions.

Other, no less important advantage, is that the collector is able to capture and convert into heat more than 90% has got to him sunlight. Even with light cloud, its efficiency exceeds the efficiency of other types of batteries.

Other, no less important advantage, is that the collector is able to capture and convert into heat more than 90% has got to him sunlight. Even with light cloud, its efficiency exceeds the efficiency of other types of batteries.

Residential Solar Panels


Solar panels - Power the Future
Solar panel - is characterized as a source of electric current through the photovoltaic cells. The advantage of solar panels due to the lack of moving parts, their high reliability and stability.
On the market solar cells can be divided into several classes:
- Low-power solar panels used to charge cell phones, PDA and other similar electronics. They are characterized by small area of the photographic plates and the relatively high cost.

Parabolic Solar Cooker

Parabolic solar cookers are a simple to use. There are several models for parabolic solar cookers. Parabolic solar cookers are very efficient. However conventional parabolic cookers need frequent adjustment to track the sun.

Solar Pool Covers

Anybody that owns an out of doors swimming pool will definitely wish to keep care of it. The good way to prevent something from getting into the water can be to use a pool cover.

Solar pool covers can help keep your pool clean, also help reduce the size of a solar pool heating system, which can save you money.

Advantages of using Solar pool covers
Solar pool covers are designed to absorb the sunlight. One of the main advantages of coatings is that they prevent heat loss. Evaporation is minimized. Thus, pool covers not only help maintain a comfortable water temperature, but also reduce the cost of heating water in the basin.

Solar panels


Modules are implemented in a constructive manner as monolithic laminate welded single-crystal elements.

- Frame solar cell is designed as a panel, enclosed in a frame made of aluminum profiles. Panel represents a photovoltaic generator, consisting of laminated glass panels c her elements. For the housing unit attached diode unit, under the cover of which placed electrical contacts, designed to connect the module.

- No frame modules are laminate on aluminum, glass, and - without the substrate. Solar cells are located between two layers of laminating film EVA. The front side is protected by an optically transparent film such as PET,