Grid Inter-Tie: The Latest Thing for a Solar Savvy World!
A Grid-tied - also known as grid-interactive or inter-tie - inverter is just what the name implies: An inverter connected to the utility grid. This allows all sorts of configuration options and most inter-ties are either come pre-optimized or are configurable for a variety of roles. For example, your grid-tied inverter could be set up so that power from your solar panels is directed to your backup batteries and that once those batteries are topped off any excess power remaining would be used by your home or business. Any power after that would be pushed out to the grid. At the same time, the inverter in this example would make sure that no grid power is used to top off the backup batteries (especially at night!) and that you only use grid power to meet your consumption needs after already incorporating power from your alternative sources (solar panels, wind turbines, etc.). If the utility in this example fails, the inter-tied inverter would automatically switch your AC and DC needs over to the battery bank.
What allows an inter-tie to be successful is the use of net metering. You could say the term 'net' in this case has a dual meaning. This is a meter that determines the net energy consumed from or delivered to the utility net. This is like a utility meter that can run backwards as well as forwards.
Keep in mind that most utility companies will not actually pay you for the energy you produce and send back to the grid. If you actually produce more energy then you consume in any given billing cycle, they will instead credit your account for the next billing cycle. Because of this fact, it is often best in most common applications to size your system to closely match your needs. In other words, you want your monthly net energy usage to be as close to zero as possible rather than show you produced an energy surplus month after month. This is the point where the most gains match the least investment.
Even if the utility companies won't allow you profit off your gird-tied inverter and energy sources you installed have behind it, right away the benefit of reduced or nearly eliminated electric bills should be apparent. In addition, even if you are connected to a utility that uses fossil fuels (as most still do), you are still reducing your overall use of the power they produce and thus the amount of carbon released into the atmosphere. In the case of grid-interactive inverters with a battery backup, you are keeping your batteries topped off for "free" while keeping them at the ready for uninterrupted, immediately available power in those situations where the gird itself might be unreliable or where the need for continuous service is critical.
- At home - You have a home that is currently on the grid. You install a PV or solar panel array and a grid inter-tie inverter. Your investment is substantially less than someone building an off-grid system because you aren't worried about batteries. This investment is also recovered faster in utility savings and more than likely incentives as well.
- The weekender/part timer - You're only at your home or cabin a few days a week. When you leave, you switch your building's power off and let the inter-tie just feed the grid. Now you're property is making/saving you money when you're not there to use it!
- Business - The weekend idea really pays for a business where typically there's no power needs on weekends or after hours. Even if you business has significant electrical needs, a grid-interactive system can not only pay for itself, but continue to reduce what ever your utility costs are on into the future.
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