This is a royalty-free image from Pixabay, courtesy of Boboshow.
Current Extreme Weather is a Topic that is Hotly Debated
What is not debated is that our lifestyles are dependent on the electricity that powers our lives and is essential to our vulnerable loved ones and the animals we keep.
Are you ready for the next storm or event that causes your next power outage?
With today’s advancements in renewable energy and storage, your options have never been greater.
Solar, wind and even hydroelectric power can easily be harnessed, collected and stored. Typically this technology creates electricity and stores that power in a series of batteries.
Using an inverter you then have common 120- and 220-volt AC power when needed.
Power Inverters convert stored power from batteries and then transform that energy into the usable power you require. This has become a very popular option for the elderly or those that have difficulties moving heavy or complex machinery and the cabling required to transfer that power. To power an entire home using a battery system would cost thousands in batteries alone, but 2 large quality cells can provide the basics for up to a 24 hour period or longer. Combination Inverter-Charging units will simplify the task and requirement of needing to charge the batteries and maintaining that charge in an all-in-one unit.
Gas Powered Generators were once the only option to power medium to large demands and are still considered the economical choice for powering our homes during an outage. Generator technology along with availability has made this the most affordable option.
Clean and efficient makes this solution the most popular. Diesel, gasoline, propane and natural gas are all common fuel types. If a particular fuel type is always on hand then that option should be considered.
Transfer Switches can automatically provide electricity from a secondary source when the primary source fails. Transfer switches are recommended for mid- to large-sized loads for ease and safety. Manual switches for temporary applications simplify the need for multiple extension cords running throughout the home, but are limited to fewer designated circuits.
Most would agree that an automatic standby generator would be the best available option. These can be costly, but those living in condos or apartments may not have that option available.
For some a small propane generator like the Ryobi 900 that boasts 60 hours of run time on a 20-pound cylinder may be enough and permissible on patios that allow propane grills. For others the newer inverter types of generators are an option due to their small form factor, light weight and their ease of use. They also offer a quieter and smoother operation, emit fewer emissions and are fuel efficient. This newer technology comes at a premium compared to a traditional unit.
For larger needs when heating or cooling, and when life support is not an option, a larger higher output generator will be required. To power an average home’s central air conditioner, the minimum is 30 or 40 amps, and then add on the additional requirements. This is where a traditional gas generator or a permanently installed unit becomes cost-friendly or attractive.
Selection and Sizing
Generators are sold by power output, and measured in WATTS.
When choosing look at the Running or Continuous watts, Not the Surge watts, this is sometimes used to lure you to purchase a cheaper unit when comparing generators.
Portable Generators, there are two average sizes 20 amp & 30 amp in your local home big-box stores. Of course there are larger and smaller units so how do you really know Watt Size you are getting?
Watts = Volts x Amps
Divide the watts advertised by 120 (volts). A 4500-watt generator will produce 37.5 amps @ 120 volts.
That same unit will produce 20.45 amps @ 220volts = 4500 (watts).
Leave a margin of safety of about 20% when sizing. Just because it's advertised 5000 watts doesn’t mean you will actually be able to utilize that full load. Generators in this category are not very efficient at producing electricity, they generally have a power factor of .8 compared to 1.1 as being ideal. The advertised watts are calculated using engineering formulas like horsepower, BTU’s, and frame size.
Another important consideration is the duration and frequency of outages. If your machine will likely run continuously for several days than a commercially rated unit should be considered. These are designed to withstand this type of abuse and will have superior bearings, oil pumps and filters. Most units will have an oil-sensing device or cut-off to prevent damage due to low engine oil.
Keep in mind that motors, pumps, and a refrigerator will all need 2 to 3 times the listed amount to start up and that is where SURGE WATTS come in to play. Along with that safety margin you should see no interruptions caused by an undersized machine.
Below is a sample of general household appliance demands:
Portable heater: 1,500 wattsThere are several online calculators to help you determine the size that’s right for you.
Refrigerator: 600 watts
Sump pump: 750 to 1,500 watts
Lights: 60 to 600 watts
Window air conditioner: 1,000 watts
Computers: 60 to 300 watts
Gas or Propane Fuel Choice or Both
Today you now have a choice of fuel. Natural gas is the obvious choice if available, it is cheap, clean and safe to use when permanent installations are considered and propane is a substitute when it is not.
Portable units primarily use gasoline but propane units are becoming popular along with "duel-fuel" or hybrid units that operate with either. Each has its own pros and cons. Propane runs cleaner but isn’t able to produce the BTU’s needed to power the generating unit that a comparably sized gasoline unit can thus requiring a larger engine or greater fuel consumption to drive the power-generating unit, resulting in a higher cost of watt produced. Propane-only units also benefit from not having to deal with fuel system failures and the gummed up and clogged carburetors that several encounter using gasoline.
Cords & Cable Sets to deliver electricity to the home should not be skimped upon. Too many fires and cord failures have occurred from using inexpensive and imported items. Always keep an eye on the cord connections, periodically removing them and inspecting them for yellowing or degradation.
Check for excessive heat just behind the cord caps or plugs. Having an extra set is also not a bad investment. A large dependable generator will do you no good without a working cord set.
The single most important consideration for all generators is the fuel system.
Ask any sales consultant--the majority of all new sales are by returning owners that did not care for their machines. Periodic oil changes are necessary but fuel that was left untreated or stabilized account for more new sales.
Consider a regimen in the spring and fall as you rotate your mowers and snow machines each season. It’s also a good time to run and treat the fuel system of your unit along with all your machines, oil changes are necessary and are based on hours of operation. Be sure to check the oil before operation. If your generator is included in each of these maintenance cycles, it will be ready when called upon and last several years.
Safety Requirements using Portable Gas Generators
Generators emit carbon monoxide and can only be used outdoors and away from windows and doors where deadly fumes can build up and enter the home. They cannot be used in homes or garages.
Always use in a well-ventilated and dry, covered area to prevent electrical shock. If it must be used in wet weather place on a well-drained surface. A temporary grounding rod with a #6 copper wire must be used if the entire bottom frame surface is not in direct contact with the earth. Gravel, cement or wood is not a suitable earth ground.
Generators with wheels / plastic / rubber feet must also be grounded in accordance with The National Electric code: NEC. See your local authority for codes and regulations pertaining to your area.
DC to AC Power Inverters
The above image is an APS1250 from TrippLite.com
This image is used with permission from TrippLite.com, ©2019, All Rights Reserved.
1250 Watts continuous 2500 Watts Surge
Auto-transfer switching option for UPS operation
Delivers clean AC power from AC or DC power source
Protects against blackouts, surges and EMI/RFI line noise
Power inverters have become very popular and are used in our every day life. Most of us have them in our vehicles that we can plug a laptop or phone charger into; others rely on a UPS to protect computers or other critical systems from shutting down. Campers and RV’s have relied on them for years to provide power when none is available.
This method of storage and transfer is at the heart of the renewable energy systems we all hear so much about. A windmill or solar-panel will produce electricity that charges the batteries that supply the inverter, and large systems can do both simultaneously. To choose this option as a mid- to large solution be prepared to do your homework and research.
Function & options inverters come in just about any size and voltage and custom units built to specific applications. Several come with Auto Switching, when your power goes out it will automatically switch to back up power. LED battery meters, remote control, noise filters and surge protectors are also options to look for.
Inverter charger like the Tripp Lite unit pictured above does both functions of power inverter and battery charger. When choosing this option take note of both charger and battery compatibility. This unit has most of the features you would expect from a well-trusted company, it is an ideal choice for smaller applications to keep an aquarium, refrigerator and a small TV running until the storm passes, larger units like 6000watt 240volt can handle modest heating and cooling. These multi-function units have all the features that have made them a solid choice when considering a Back-up solution.
Quality VS Cost
Inverter technology has improved along with the advancements of renewable energy. Modified sine wave was the only option under $1000 with pure or true sine wave being the best option.
Today most quality units will produce true clean AC power that will not affect your electronics or cause your refrigeration compressors to work harder, but still check to make sure you are receiving a Clean Power source.
Size and Efficiency
Plan and design your system around your needs just as you would with a generator, calculating your running and surge watts, except now you have to plan for TIME. Larger and multiple batteries will supply more time but will require a sophisticated charger to sense multiple batteries without over-charging and damaging them. The marine industry has affordable chargers that can accommodate up to 3 deep-cycle batteries for under $200.
The larger the inverter the more energy it will consume to convert DC to AC energy and the rule is 5%-10% so a 1000-watt unit might consume 100 watts to run a 500-watt pump (600w), and a 10,000 watt unit might use 1000 watts to convert enough energy to operate the same pump (1500w) so don’t overdo this one.
Charging the batteries and keeping them charged is of importance when used as an emergency back-up power source. There are several types of batteries and each requires a charge cycle that is unique to the type used. Auto or Cranking, Deep-Cycle, AGM and GEL all have specific charging characteristics and if not met will damage or shorten the battery's life. Automatic battery chargers can sense a batteries charge and keep it charged but multiple battery systems can confuse this technology and the charger may continue the charging cycle until the batteries fail. Only use a charging system designed for the application in use. A small single cell system does have the benefit of during an outage you can use your vehicle's engine to charge a battery or run the inverter but will be limited to the size and number of appliances you can use.
Battery Technology has improved and is an entirely different topic open for debate. We now have several types to choose from that can cost over $500 per cell. Deep-cycle batteries that are designed for repeated charging and discharging are required for this type of standby application. There are 3 types, each with distinct advantages. The traditional Flooded Lead Acid; FLA, Absorbed Glass Mat; AGM and the preferred Gel or Gel-Cell are all types that require a specific charger that is compatible with each or poor performance and or damage can be expected.
Most importantly ALL BATTERIES NEED to be ventilated to prevent the build up of poisonous and possibly flammable gasses.
Each type has its pros and cons and should be thoroughly reviewed to determine the correct type needed to best match your particular system requirements along with safe handling, use and storage.
Traditional FLA has a definite cost advantage but can degrade sooner. This option is suited for heavy frequent usage where outages are weekly or monthly occurrences. Deep-cycle batteries are built with heavier lead plates and can take the charge and discharging with ease compared to standard types that are meant to stay charged and only discharge a small percentage when used. They also resist the corrosion during these charging cycles. But they can spill corrosive acid, vent poisonous fumes and are susceptible to freezing making them less than ideal for indoor and outdoor installations in colder regions.
AGM Absorbed Glass Mat is a great choice and balance between old and new. The advantages are numerous with very few disadvantages other than cost and critical charging requirements. Most important is they are spill proof and well suited in cold environments. They also store well without needing the typical maintenance that the FLA requires.
Gel or Gel-Cell is an ideal battery for standby power storage. Costing more than the AGM these are used in computer UPS Uninterruptible Power Systems and emergency lighting systems. Sealed and maintenance-free, gel provides a higher cycle rate, longer life span and are not as sensitive to charging as the AGM.
The down side is that they are not well suited for fast heavy current draws and can fade quickly with very little warning at the end of their long life cycle.
Calculating Battery Runtime is best described as an educated guess. Batteries have efficiency losses inherent to type, age, rate of discharge and the ambient operating environment. To think you can run a 10 amp appliance for 10 hours on a 100Ah battery is not realistic (10 x 10 = 100) and then let’s not forget the energy needed to run the inverter.
An example of these losses is the Peukert Law and is expressed below.
100Ah divided by 10 amps = 10 hours then divide by battery type loss (FLA) 1.3 = 7.6 hoursWiring requirements for inverters are calculated on current draw or amps. Calculations using 12 volts require larger conductors and in conjunction larger conduits to shield and protect them. Because of this greater cost large systems will frequently operate at higher voltage levels, Inverters at 24 volts are common and available. A 36 or 48 volt system are common for larger renewable systems.
Again, not taking into account battery age, operating temperature and other factors needed.
Typical losses for lead acid batteries:
FLA: 1.20–1.60 AGM: 1.05–1.15 Gel: 1.10–1.25
Using the same methods form earlier Watts = Volts x Amps to get an idea of the costs of wiring***
This image was created by and used with permission from RMS 03/05/2019, ©2019, All Rights Reserved.
Planning and Choosing a Standby Power Solution should be carefully considered and discussed with experienced designers and contractors who have successfully completed several installations.
Ask for references and ask to see that person's designs. Do your homework and research so you will better informed and know which questions to ask when choosing.
The equipment you select should be trusted, well known brands that specialize in the application you choose. Technical support is critical, from design to service, look for brands that offer phone support and have a proven track record of favorable customer service.
I hope this article illuminates and inspires and leaves you educated and informed. The provided information is intended to break down what may be required and the obstacles you may face when choosing your back-up power system. Please seek a local professional to help you with your selection, installation and operation.
Remember “There are old electricians and bold electricians, but there are NO old bold electricians!”
Please stay safe,
***This Informational article is a generalization and is not a technical reference, design standard, or installation guide, or is it to be used in a manner not intended.
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Author Profile: @siggy
@siggy is an industrial and automation electrician working for a major auto company in Detroit, MI.
He grew up with the great lakes outside his front door and has always lived within a few minutes walk. He is an avid boater and fisherman, and you can find him on the water whether it's frozen or soft.
He has been keeping fish on and off since the late 70's.