Most PV solar energy systems installed today are “grid-tied”. This allows the homeowner to use both locally generated solar power and power from the utility via the power grid without interruption. Any surplus electricity generated by your solar panels is fed out to the electric grid, earning you credit on your electric bill. Whenever there is a power outage, the standard solar design also must shut down and not allow electricity to flow. This is a mandated safety precaution. It protects you and especially any utility workers that may be addressing problems outside of your home. They don’t need any surprise shocks from electricity generated by rooftop solar energy systems. These are referred to as “islands” of independent power.
In Pennsylvania and New Jersey the ability to operate independently of the grid is not prevented, simply regulated. These “anti-islanding” regulations can be satisfied while powering your home with your own energy sources. Power outages will still be inconvenient. But they will no longer prevent you from maintaining a basic life by operating appliances of your choosing.
The Perfect Solution – Battery Backup for Emergency Power
Batteries have been used for energy storage for over a century and in some forms predate the commercial developments of Edison and Tesla. In modern times they are used for two primary purposes:
- Batteries provide the smooth and controlled use of energy on a continuous basis as they charge and discharge. The battery in your car is one example.
- They also allow stored power to be used at specific times in the future. Some call this “time shifting” your production.
This smooth, future delivery of power can be vital in emergency situations. Electricity production from a solar energy system varies directly with the intensity of the sun, the passage of clouds, etc. And when nighttime falls, of course there is no production. So batteries can substitute for your grid-connected, smooth power supply whenever activated.
About Solar Energy with Battery Backup
There is more than one technical approach to providing backup power when needed. Whether we are designing from scratch or we are asked to retrofit backup to an existing solar energy system is one factor that impacts design choices. Regardless, each design must monitor and manage power supplied to your home from the grid (AC power), as well as from the solar panels and batteries (DC power). As you may know, no matter what the power source is – AC or DC, your home is built to use only AC power.
Exact Solar has chosen two basic design approaches that cover almost every need and condition for battery backup or emergency energy.
A leading edge system. We select components that deliver the most efficient operation over time. Power is monitored to automatically divert to emergency battery power in an almost seamless way. An LG Chem lithium ion battery provides long life and high durability. This type of battery is famous for high energy density, meaning they typically require less space for the same amount of power. They are also known to hold their charge extremely well when not in use.
The best in class system is suited for systems designed for battery backup from the start. Retrofits are available. Contact us for more details.
The standard system. We have selected components that work well with a variety of existing solar energy systems. This package may also be chosen when designing from scratch. Like the best system, charging and switching to backup can be automated. Maintenance-free, sealed lead acid batteries provide reliable power when you need it.
Both of the Exact Solar packages include the following:
- An Uninterruptible Power Supply (UPS), typically provided by one lithium ion battery or 4 traditional lead acid batteries.
- A controller to efficiently manage the charging of the batteries (Charge Controller) both while your home is connected to the grid and when disconnected in emergency situations. This may be either built-in to another component or a separate device.
- A special systems control to disconnect your home from the grid during an outage. Our product meets Pennsylvania and New Jersey codes and guarantees to the utility that there are no hazards.
- A separate sub-panel to service your “critical loads” during outages. This is your UPS circuit, and you choose in advance the outlets and appliances that you want active in emergencies.
By choosing either approach to battery backup the homeowner can be confident they have dependable service for years to come. Solar with battery backup systems will provide emergency service that is limited only by the available sunshine for extended utility power outages. You may optionally expand your emergency power margin by adding batteries and making provisions for utilizing an alternate, small generator in addition to your solar panels for extremely severe and long term security. This can give a homeowner extended, 24 hour service under the most severe outage situations.
About Batteries for Solar Energy Storage
Because the batteries are needed without planning or notice, quality and integrity are most important. At Exact Solar, we are certain that both our choice of traditional lead acid style and lithium ion products are superior in their class.
Our traditional lead acid batteries are commonly used in some of the most demanding and rugged environments, such as off road vehicles and boats.
Our top of the line lithium ion style has been designed explicitly for the requirements of a solar plus storage system. This storage technology is very advanced from use in personal communication devices and in many hybrid and electric vehicles on the road today.
The Limited Solution – A Secure Power Supply Outlet
There is another option for operating without power from the grid. Using an SMA Sunny Boy inverter, it allows the homeowner to have one, live outlet in the case of a power outage. However, it may not be compatible with every existing system. More importantly, the outlet will only function when there is sufficient sunshine. Contact us to learn more about this design and its limitations, including whether your home may be suitable.