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How grid tied solar power systems work
Section 1.6: More Explanation of Grid-Tied Solar Power Systems
Since grid-tied solar power systems are by far the most common, let's delve a little deeper into their features.
Utility connected systems generate electricity from the sun, supply the house with its needed electrical needs, and then push any excess electricity onto the utility grid. Thanks to the Public Utility Regulatory Act of 1978 (PURPA), public utilities are now required to purchase this surplus electricity from small producers, such as you and your house. This allows for net-metering, which means that utility must pay you for the electricity you put back into the grid. This generally causes your electric meter to run backwards and creates a credit on your power bill. However, the utility does not necessarily have to pay you the same rate that you pay them for their electricity. This means there is often a 'gap' in the utility rates.
There are generally two types of grid-tied solar power systems:
•Systems WITH Battery Back-up•Systems WITHOUT Battery Back-up.
Utility Connected Systems WITH Battery Back-up
These systems are very useful in areas with frequent power failures. Provided there is ample sunshine, these systems give the customer more autonomy, while still providing a backup system in the utility grid.
Advantages of these systems include:
•With proper system design, they provide continuous power to the customer regardless of utility availability or weather conditions.
•These systems make it easier to manage your power consumption, production, and storage.
•Depending on the utility company's policy, the cost of the batteries can sometimes make up for the rate 'gap', meaning it is worthwhile to store the excess electricity you produce as opposed to selling it back to the utility.Disadvantages of the battery back-up systems:
•Increased system complexity, more components to install.
•Increased cost of the system
•Increased maintenance of the system
•Decreased efficiency of the overall system
•Environmental issues: The manufacturing and disposal of batteries involves chemicals and metals that most eco-minded consumers would rather avoid.Utility Connected Systems WITHOUT Battery Back-up
These systems are the most popular for their relative simplicity.
Advantages of these systems include:
•Cost effectiveness: when combined with net-metering systems owners can see payback times from 5-10 years.
•Simplicity of design and installation
•Higher overall system efficiencyDisadvantages of the systems without battery backup:
•Does not necessarily provide backup power in the case of grid failure
•Does not allow for power management
