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What is Battery Backup Power?

Back-up power allows you to continue using certain (or all) appliances when utility provided grid electricity is not available.

If a hurricane knocks out the power lines, if there are rolling black-out's, or if you simply want to disconnect from the grid, a back-up power system with a bank of batteries which can be kept charged - with solar panels or gas generator or wind generator OR BY THE GRID WHEN IS IT OPERATING - can supply power for a limited amount of time, depending on how many batteries you have and your battery charging method.

View our complete back-up power systems.
Your choices are, in order of complexity and cost:
  1. Install a Emergency Battery-Based Back-Up System which can be kept charged by the grid when the grid is on line. This system will provide power until the batteries are depleted.
  2. Install a battery-based backup system which can be kept charged with either grid or gas generator or solar panels. This can work in a home or business that has grid power or in an offgrid situation where there is no grid power.
  3. Or, if you already have a solar gridtie electrical system, you can install a battery-based backup system which can be kept charged with the grid, when grid electricity is available, or with your gridtie system’s solar panels even when the grid is down. This can be planned at the time of purchase of your gridtie system, or it can be added later.
Battery Backup System Diagram
Solar Panel
Solar electric panels - a.k.a. solar modules, photovoltaic (PV) panels

Pointed towards the sun, solar panels capture the energy in sunlight and convert it directly to DC electricity. There are three general families of solar panels on the market today—single crystal silicon, polycrystalline silicon, and thin film. More on the different types.....

PV modules are very durable and, because there are no moving parts, long-lasting. Most carry 25 year warranties. Solar panels are assigned a rating in watts based on the maximum power they can produce under ideal sun and temperature conditions per hour. You can use the rated output to help determine how many panels you need. Multiple modules mounted together are called an array.

Solar Panels Mounting Racks
Array Mounting Rack—a.k.a mount, racks, trackers

Mounting racks provide a secure platform to keep your panels fixed in place and oriented correctly. Panels can be mounted on your roof, atop a steel pole set in concrete, or at ground level. The type of rack you choose will vary considerably depending on your budget, climate, building codes, and personal preferences. In areas where it snows a lot, you may want to be able to sweep the snow off periodically.

Array Combiner / DC Disconnect
Array Combiner/DC Disconnect

The DC disconnect is used to safely interrupt the flow of electricity from the array of solar panels. It is an essential component when system maintenance or troubleshooting is necessary. The disconnect enclosure houses an electrical switch rated for use in DC circuits. It also may integrate either circuit breakers or fuses, to combine the electricity of multiple sub arrays of solar panels.

Charge Controller
Charge Controller

The Charge Controller operates the array at its maximum efficiency and feeds the electricity into the inverter after the battery bank is filled to capacity. A charge controller also protects the battery bank from overcharging. When the battery bank is fully charged, the controller interrupts the flow of electricity from the PV panels. Batteries are expensive and lose potency when under or over-charged, so the controller extends the life of the batteries. A charge controller built into a grid-tie inverter uses maximum power point tracking (MPPT) to optimize the array's output, increasing the energy it produces.

Battery Bank
Battery Bank

The battery bank is where the electricity is stored from the solar panels and sometimes from the power company electric lines. This is the power supply center and determines how long you have power if there was little sunlight for consecutive days or if the utility grid power goes out. Batteries are large part of the cost of a solar powered system so it is important to choose the rest of the solar powered system to optimize battery life. Batteries last the longest when they are properly maintained and not under- or over-charged

Inverter Solar
Inverter

The inverter transforms the solar-produced DC electricity into the AC electricity commonly used in most homes for powering lights and appliances. Grid-tie inverters synchronize the electricity they produce with the grid's "utility grade" AC electricity, allowing the system to feed solar-made electricity to your home and to the utility grid. Battery-based inverters for off-grid or grid-tie use often include a battery charger, which is capable of charging a battery bank from either the grid or a backup generator during cloudy weather.

Inverter Solar
Inverter

Bidirectional KWH Meter, a.k.a. your electric meter. Most homes with grid-tied system will have AC electricity both coming from and going to the electric utility grid. A bidirectional KWH meter can simultaneously keep track of how much electricity flows in each of these two directions. This is information you need to monitor how much electricity you are using AND how much your solar electric system is producing. The utility company will probably supply this meter, but you may have to pay for it.