Solar Water Heating Definitions

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Solar Water Heating Definitions

Learn the lingo before you embark on your solar water heating adventure and investigations.

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Solar Water Heating Definitions:

So often many consumers are frustrated by all the lingo of terms that are thrown around with regard to solar systems and green energy systems.

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This is especially true in the architectural and engineering communities as it serves as sort of a "short-hand" for the people designing and installing the systems.

What we will hope to do here is explain many of the major terms you will run into to, with a brief explanation of what this system does, how it operates or if it benefits you or not.

Solar Collector

Solar Water Heating Definitions: Solar Collector

Solar Collector:
This is the actual panel that houses the collection system of piping that where working fluid circulates and carries the heating fluid to the distribution system.

Collectors can be made of an array of copper piping attached to a flat solar absorber that is painted in high-efficient heat absorbing paint.

The Collector panel is usually topped with a glass top and is housed in an insulation box of various materials.

Another type of Solar Collector is an array of metal tubes surrounded by an evacuated glass cylinder. This is typically a higher efficiency method, especially when it is combined with parabolic mirrors to concentrate the sun rays on the piping.

These systems are usually housed in industrially produced frames for an even better appearance and higher efficiencies.

Open Loop:
The Open Loop refers to the fluid from the actual collection system. With this type of system, the main household water supply is circulated directly through the collection system.

Note that this is also commonly referred to as a 'Direct' System.

Closed Loop:
The Closed Loop uses an anti-freeze heat transfer fluid, which passes through the collector. This fluid does not contact the main household water at any time, but uses a Heat Transfer System for heating the domestic water.

Note that this is also commonly referred to as an 'Indirect System'.

Freeze Protection:
Incorporates anti-freeze fluids in the transfer fluid that circulates through the collector panel system.

Freeze protection is used in both direct and indirect systems

In some types of direct systems, freeze protection is achieved by manually draining the system. This approach is used in areas that experience freezing conditions very infrequently.

Heat Overload Protection:
There can be a tremendous amount of heat generated within the Collector Panel. If the circulation systems fail or the temperatures get above a certain threshold, there should be a pressure release valve within the system.

This is also referred to as a "Heat Dump".

Organic Vegetables

Solar Water Heating Definitions: Heat Transfer System

Active Circulation Systems:
These systems force the flow the working fluid through the pipes with a small circulation pump. While these pumps are quite small (1/6 to 1/12th hp), I prefer to power them with a small solar panel as well. This keeps our energy usage very close to zero.

Passive Circulation Systems:
These systems rely on thermodynamics or natural convection to continually circulate water through the system, without the need for a pump.

Heat Transfer System:
Most systems will not use the actual water that is circulated through the system. The reasons for this is that a closed loop system is much easier to control from freezing conditions at night, during cold weather.

The fluid used then contains a form of anti-freeze coupled with a corrosion inhibitor to protect the system.

This type of system also includes a heat exchanger. The heat exchanger consists of a coil or an array of copper pipes on the closed loop portion of the collection system and is located within the water storage tank.

Fuel Cells

Solar Water Heating Definitions: Circulation Pumps

Drain Back System:
The drain back system is another popular method to utilize what is called a drain-back system. This system uses gravity to drain the pipes in the panel and circulation system, back to the water storage tank.

There is a temperature probe that controls the circulation pump. The water storage tank is not pressurized and the pipes empty very easily without the use of anti-freeze.

In order for this system to work, the water storage tank needs to be located lower than the collector.

The attraction to this type of system is the lack of mechanical or electrical parts that can break down or require regular inspections and maintenance.

Smart Home Technology

Solar Water Heating Definitions: Convection Heat Storage Panels

Convection Heat Storage Storage:
These types of systems often incorporate flat plate evacuated tube collectors. The main difference with these types of systems is that the water storage tank is incorporated directed into the collector system.

Water is transferred between the collector and the storage tank via thermo siphon and does not use any mechanical or electrical systems. This is also know as a "Compact System".

Active System Intelligent Controllers:
If you want the optimum in efficiency, the intelligent controller is for you. It allows you to have a great deal of control over the backup heating system, measurements of energy usage, safety functions, integrated time-clock functions, domestic hot water loop control and much more.