Green Homes

What is Passive Solar Heating ?

Solar energy is free, renewable and non-polluting, so why isn't it used everywhere today? Most people have the same implementation questions: Do you have to change your lifestyle with a passive solar system? Are there concerns with its variability and is it worthwhile? Are you better off going with a traditional heating system? Solar-based living does not necessarily mean a house full of glass and complicated electronics. There are some simple guidelines that will enable your home to enjoy the sun's energy to the fullest.

Solar Water Heating

Most people are aware of using solar heating for hot water supply in the home. This is because about one third of our home energy bill goes towards hot water heating, as Florida State's electrical utility companies confirm. It is the third highest cost, following heating and cooling.

Solar Hot Water Systems

A solar water heater can operate together with your current electric or fossil-fuel water heater to supply a portion of the home's total hot water heating requirement. This will reduce greenhouse gas emissions, air pollutants and the cost of your water heating.

Photovoltaic System Grounding

Grounding is used to dissipate electrical energy safely when faults occur. This is the third pin on your extension cord plug which allows electricity to flow when system insulation fails.

Basic Principles of Solar Thermal Systems

As soon as you start looking into a solar thermal installation, you will run into certain terms and principles that may be unfamiliar. It is essential that you understand these ideas, so that you can see what is needed and make intelligent decisions when offered choices by professional installers.

Pressurized Solar Thermal System Pumps

One of the advantages of a pressurized solar hot water system is that the solar loop is always full. This means that the pump has no static head pressure to overcome (just friction head), so low-head, slow-starting pumps can be used effectively. And those pumps can be run on power from a PV array, eliminating your grid-tied power costs for operation.

What are Drainback Solar Thermal Systems?

Drainback solar hot water systems are not as flexible as pressurized systems, but still work very well in both residential and business applications. They are very efficient if they are planned and installed carefully.

Drainback Solar Thermal System Pros and Cons

These systems have many advantages:

They can use simple water as a solar fluid for lower cost.
They are very efficient if they are planned and installed properly.
They are ideal where the installation will lie idle for extended periods.
Since the system empties when it switches off, the solar fluid has a long life.

It's also important to consider these disadvantages:

Drainback Solar Thermal System Tanks

Drainback installations use three tanks to heat the domestic water supply. The two main tanks are just like those used in pressurized solar thermal systems. However, the third is specialised – the drainback tank, which is installed on the solar loop.

The two main tanks are installed in standard fashion: the one heated by solar energy is piped in series before the backup grid-tied tank, so that the sun-heated supply is topped up with heat in the second tank if necessary.

Drainback Solar System Pumps

Unlike pressurized installations, drainback solar hot water systems have a fair amount of head to overcome before they start operating properly. Consequently, they need more powerful pumps. The choice of pump is absolutely critical to the system.

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