Nothing makes me more nervous than when the power goes out here in Northern California. Non-disaster U.S. power outages are up 124% since the early 1990’s. The number of people on average affected on a daily basis by U.S. power outages are now up to 500,000. The cost of new utility lines run an average 2MM per mile. Add to those facts hurricane season, blackouts and winter storms on the way raises the question, should Americans look at the rising blackouts as unusual events or a warning sign and start to prepare at home? Is an off-grid solar or battery backup uninterrupted power supply important to you?
An independent, or off-grid battery backup, system stores energy for nights and cloudy days in a bank of batteries. However, those of us with grid-intertied electric systems or houses and businesses which totally rely on the local utility company, lose all power during a temporary blackout or when weather damage knocks out power lines for days it can be devastating if not life threating.
We have some friends who live in the Sierra Mountains who were left without power when an intense winter storm rolled through with four feet of snow on the ground. No power, water or heat for days might have normally been a problem but they were prepared with a off-grid battery backup power system that was charged during the day by a solar system.
How an Emergency Back-up Battery System Works
For utility grid connected backup power, the battery bank provides the power for backup loads. The first decision is deciding which power loads are critical to power during a blackout. Those items are singled out with a electrical sub panel. To isolate the power you need two load centers, the main distribution panel and of course the electrical sub panel for your backup emergency power requirements.
Circuits feeding the refrigerator, lighting circuits and any other necessary loads are pulled from the main breaker panel into the isolated sub panel. This sub panel can be located next to your main panel.
Next, a 240-volt circuit in the main panel is routed to feed the back-up, allowing the batteries to stay charged at all times. You installers will then route the power through the inverter to the critical panel, allowing those loads to run continuously. In the event of a blackout or brownout, the back-up system will take over in less than one third of a second. Note: It is possible to wire and program your backup system to take advantage of your existing solar panels for assured power during extended blackouts.
Evaluating the electrical loads that the emergency power battery bank must service
When using batteries to power safety loads, you have to generate and store every watt-hour used which means you need to first convert the “have to have” loads to make the most efficient use of electricity. LED lights, more efficient well or sump pump, minimal heating requirements.
Power should only supply power to loads that are truly necessary which means you will need to look at each item or “critical loads”. Critical loads as defined by the National Electrical Code are loads for life support, safety and emergency vital functions.
Sizing your battery backup system
Sizing your back-up system, which is the first step, means looking at your energy load. To establish your critical electrical load, decide what items you want backed up and how long they’ll need to run while the power is out. This information serves as the basis for all of your power calculations when sizing your battery backup system.
Most appliances have nameplate ratings marked with Amps, Volts and Watts. Remember amps (A) x volts (V) = watts (W). Multiply the watts used times the number of hours the appliances will run. For more accurate measurements of your power use per appliance, you can use a meter to gage your actual electrical use in watts. Be conservative with the number of appliances you back up. Draining batteries completely of their power will ruin them.
A 4400-240 backup battery power system includes eight sealed maintenance-free batteries. Capable of running large critical loads such as refrigerators, it can produce up to 9.6 kWh or 9,600 watt hours. A inverter is then used to provide 120 and 240 volts input/output power.
Consider security, safety and convenience when considering off-grid battery backup. Add a few solar panels and the system qualify’s for a 30% tax credit.