Solar heating panels come in two different classifications. This is based upon the fluid that is contained within the panels themselves. The two classifications for solar panels heating are either liquid or gas. The panels are even further classified down based on the temperature collection in which they work. These are of course low, medium and high.
The low temperature collectors are designed to only work from 35-30 degrees above normal temp and are primarily used for heating swimming pools.
The medium temperature solar are designed to work from 15-200 degrees above optimal temperature. The primary use for this type of panel is space heating and water heating.
The high temperature
The purpose as well as the use of the heating panels will explain the cost as well as the material that they will be composed of. The higher the end temperature, the more glazing of the panel will be required as well as the amount of insulation that will be needed to maintain the panel.
The only purpose for unglazed solar heating panels would be for the heating of swimming pools since they do not retain or cannot make much heat from the solar energy that is produced. In most cases the life of these panels tends to be about 20 years.
The purpose of the glazing on the solar water (or air) heating panels is to work as a lock. The glaze traps in the solar energy after it has been absorbed and stores. This would not be very practical when looking to increase the temperature of your pool by only a few degrees. It is however very practical when you are looking to either heat your home or you are looking to heat a building. The logic behind this is that there are going to be times when your home will need to be heated when the sun is not out so therefore you would tap into the stored solar energy to produce the heat that is required for your home.
When considering efficiency of your solar heating panels, take into account what they are made of. In regards to the glazing, high iron tempered glass seems to work best. This is because it has a low reflection rate. The casing should be made of steel so as to protect the panel from heat loss due to wind also because of its durability. In essence for your heating panels you should try and make sure they are not made of plastic and that they do not contain a lot of aluminum as they will generally not hold up. Make sure to look into what materials as well as the insulation that is used in your solar heating panels so as to insure that you are getting the most for your money when it comes to what you choose.