Published on May 14th, 2014 | by Guest Contributor8
A Power Backup Solution For The Achilles Heel Of Grid-Tie Solar
Working in the solar industry, I’ve noticed that the number of people calling who are interested in installing solar-electric (photovoltaic) systems increases substantially after a natural disaster. It’s very understandable considering that after Hurricane Sandy, for example, 8.1 million homes lost power in 17 different states as far west as Michigan, and for some towns in New Jersey and New York the power stayed out for up to two weeks. Unfortunately, the truth is that the most common and most affordable option for going solar, a grid-tie system, has one big fat Achilles heel: your grid-tied solar panel system will not work when the grid is down.
How does a grid-tie solar system work? As the name implies, the system is tied into the electrical grid (i.e. power lines) which feeds your home electricity to power your appliances, etc. Your home is already connected to this power grid regardless of solar panels. What most people don’t know is that this connection is a two-way street— electricity can flow both from the grid to your home and from your home back into the grid.
This two-way energy flow feature of the electric grid is exactly what makes grid-tie solar systems so affordable. Solar panels on a grid-tie system generate electricity when the sun is shining, and this electricity is then routed to the home’s primary electrical distribution panel. The home immediately uses the electricity generated by the solar panels, and any excess electricity is fed back onto the grid, spinning your meter backwards. At the end of the month, you will be charged by your utility company based on your net energy usage (in most places). In this set-up, the grid essentially acts as your battery “storing” the excess energy produced during the day to be used at night.
So, why does a grid-tie solar electric system shut down when the grid goes down (exactly when you need the power the most!)? This is a safety feature built into the inverter to protect utility line workers who could get shocked repairing a power line that is being back-fed with energy.
What about off-grid solar systems? Traditional off-grid systems are very expensive for many reasons including the cost of batteries, a charge controller, a specialized inverter, and the cost of installing. An off-grid inverter will cost you around $6,000 (twice as much as a grid-tie inverter), the empty battery rack runs around $2,000, and each battery will cost around $600.
In response to this glaring downside of grid-tie solar panels systems, PluggedSolar has come up with an ingenious solution called the PluggedSolar Plug-In Power Backup. The Plug-In Power Backup system installs easily in three steps: simply connect the batteries that come with the system, plug the system into a 110/120V wall outlet, and finally, turn the system on. The way that it works is that, while the grid is up and power is working, the Plug-In Power Backup is charging the batteries and using the electricity from the grid or from your grid-tie solar panel system.
When the grid fails and the electricity goes out, you can power your lights, appliances, medical equipment, etc. by plugging them directly into the power backup system. In the event that the power grid is down for a longer period of time, the PluggedSolar Plug-In Power Backup batteries can be easily recharged using your solar panel system. To recharge the batteries, simply unplug the Plug-In Backup Power system from the 110/120V wall outlet; unplug your PluggedSolar plug-in solar panel system from the wall outlet it is connected to (either 110/120V or 220/240V, depending on the size of the system and your state’s regulations); and connect your solar power system to your Plug-In Power Backup power input connection. This is a grid-tie hybrid system that combines the advantages of a grid-tie system, while also ensuring that you will have access to electricity when the power goes out.
Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.