Grid-Tie or Off-Grid? Solar Energy Facts

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There are two basic types of systems when using alternate electrical power such as that generated by solar photovoltaic (PV) or wind turbines – grid-tie and off-grid.  The following is an overview of solar energy facts for both types of systems.

Off Grid

Off-grid is the term used when your house has no connections to the electrical grid. These systems have traditionally been limited to those of us who live out in the boonies. This does not necessarily mean you have a system to generate electricity, although most people do to some extent.

Many “city folks” aren’t aware that if you buy undeveloped land far off the beaten track, the electric company is happy to install electric service to your land from the nearest “distribution point.” They are equally as happy to charge you for every penny of that work, including the labor, the poles, and the wire it takes to get to your land. This can add up to a huge amount of money. We’ve heard people who have had estimates as high as $50,000 for electric hookup – which is more than a sweet off-grid system would cost these days. This choice is fairly easy – if there is no access to the grid, the choice is probably off-grid. For these folks, it makes sense to have an off-grid system. For others, the line is much more blurry.

What if you live where the grid is already delivered to your house? In order to go off-grid, you will need a way to generate the electricity. If you intend to use any electricity when the sun is not shining, then you’ll also need to have a way to store the electricity – such as a bank of batteries. This can add up to a lot of money and the batteries require maintenance and replacement at regular (although fairly long) intervals.

Grid-Tie

A grid-tie system is for those folks who have access to electric service. They usually get their power from a utility company and pay a monthly bill. These systems are becoming more and more popular with people who have solar photovoltaic (PV) panels installed and use those panels to run their appliances, tv’s, etc. during sunny days. If their PV panels generate more electricity than is being consumed by the household, that excess electricity is measured and routed into the grid. The extra amount of electricity is then credited to the household’s account. At night, when the PV panels are not generating electricity, the household uses power from the grid. This usage is deducted from any of the excess that was generated during the day. At the end of the month, if more electricity was generated and fed to the grid than was used when the grid power was required, the household gets a (usually quite small) check from the utility service. This whole process is referred to as net metering.

Net metering grid-tie systems can be a good way for city dwellers to go. There are a couple of drawbacks to these systems. The major one is that when the grid goes down, the grid-tie system also goes down. If your neighbor doesn’t have electricity, you don’t have electricity. This is done for the safety of the workers who will be repairing the lines when service is interrupted. They have to know that when the power is turned off, it is really off.

(Please note that there are still people who seem to be anti-alternative energy and like to say that this automatic service interruption is due to “surging” caused by solar panels hooked into the system and is destructive to the utility’s lines.  This has never been accurate – since it is a requirement of grid-tie systems that a device be included that prevents surges and regulates the amount of power before it goes back into the utility’s power lines.)

Another disadvantage (only a source of irritation, really) of grid-tie systems is that when you buy electricity from the utility company, you pay the “retail” price and when the utility company buys it back from you, they only have to pay the “wholesale” price – as your grid-tie system is now officially an electricity generating plant.  (Another point to remember is that every check that is received from the utility company is income and must be declared on your taxes.)

There’s a bit more to consider when deciding between grid-tie and off-grid, so the resources below may be of some value to you in deciding.  Please let us know what you would like to hear about in our Solar Energy Facts series.

Pro Grid-Tie

Pro Off-Grid