When shopping for electrical backup systems, homeowners come across two similar yet very different solutions: Batteries and Generators.
These two systems offer backup power when the utility grid goes down. The main difference between them is their source of energy. Generators utilize traditional fuel sources, while energy storage systems can be charged by solar power.
In this article, we are going to compare batteries and generators.
Generators are exceptionally reliable. They are dependable and will run if they have fuel. Generator fuel includes diesel, natural gas, or propane. Select generators can even be attached to existing natural gas lines to allow for minimum maintenance and refueling. If a generator is not directly connected to a natural gas line, the fuel level will have to be monitored and replenished to ensure the generator does not turn off.
Generators create AC electricity that typically is not as stable (in terms of the frequency range) as the utility grid. Still, they can power very large loads for long periods.
When operating, generators are not quiet. They will make a constant noise for the entire time they are on and generate exhaust fumes. Many homeowners do not want loud equipment running through the night.
Generators are typically less expensive upfront. When factoring in the fuel price needed to power the generator, the cost grows the more the generator is needed.
Generators have decently large footprints and a lot of moving parts. There is the possibility of a mechanical issue with the motor. In backup situations, this can lead to uncertainty that can leave a home without power until the mechanical problem is addressed.
Generators are a great application for areas where there is a lack of sun or extreme temperatures. Generators can run on natural gas and operate in extremely cold climates where battery systems tend to struggle.
Battery systems have the same purpose as a generator; to provide electricity when the utility grid is down. However, the way battery systems operate and store energy is entirely different from a generator.
Batteries store energy through many chemical reactions depending on the battery type that can discharge at various DC power rates. The DC power is put through a battery or hybrid inverter that has a maximum AC output. This power can then be applied to loads.
Battery systems are virtually silent. They can typically be mounted or stored in a garage or shed.
Battery systems are a lot more expensive, but there is essentially no cost when paired with a solar system when charging the battery.
The limiting factor of a battery is its lifetime. The lifetime of a modern battery backup system is dependent on the number of cycles the battery experiences. The two standard battery configurations, backup and peak shaving, will cycle your battery at different times and have a different effect. Most battery manufacturers have warranties that will cover either ten years or 6,000 to 10,000 cycles.
Read more about: Prolonging Battery Life
Battery systems have limited storage (compared to a generator connected to a natural gas line). This is an issue when it comes to power outages that last longer than a few hours. If a battery inverter is sized correctly, the battery bank will supply sufficient power until the battery bank is depleted. The battery bank would then need to be recharged before it can be discharged again.
One of the advantages of a battery system is you can increase your battery bank size after the initial system has been installed (depending on your hybrid or battery inverter input capacity). This allows larger battery banks to be utilized with smaller battery inverters, allowing for a “larger fuel tank.”
When you cannot increase a battery bank in size, the solution is pairing the battery system with solar. The excess solar can charge the battery during the day if it is not directly consumed. This allows battery systems to be sized based on how much energy is needed during non-sunlight hours. Large battery banks can cost upwards of $20,000 in some cases. It should be noted once a battery and solar system are installed, there is no additional fuel cost but actual savings in electricity costs.
Battery systems have a smaller temperature range that they can operate in. This limits the battery system’s performance and can lead to an underperforming battery. Most installations in extreme climates utilize insulated sheds or auxiliary structures to maintain a suitable operating temperature.
Applying generator power is the traditional way of backup. These are loud, fuel-driven systems that allow for electricity as long as the generator is sized correctly and there is a constant fuel source. Generators are initially cheaper, but cost a lot to operate.
Battery systems utilize excess solar energy and store it through chemical reactions for later use, generally during a time when there is no solar resource available. Battery systems run quietly and do not have rotating parts. They also do not create fumes or exhaust the way a generator would. Battery systems are scalable after they have been installed and require minimal maintenance. If you already have solar, a battery backup system is a great way to harness the excess energy sent back to the utility grid.