If you are concerned about power outages and would like to become more resilient, whether you need power to keep working from home, for medical appliances or just to ensure you can still live comfortably in your home in case of a prolonged outage, a battery backup system might be the perfect match for your solar system.

A battery backup system makes your home more resilient

A battery backup system can work together with your solar system, by storing the energy produced by your panels. During the day when the sun is up, the excess energy you don’t need at the moment is either stored into your battery or sent back into the grid in exchange for credit on your future energy needs from the utility (after sunset or before sunrise).

When installing a battery backup system, it is critical to identify the main appliances needed during an outage. These will be re-routed to a new “backup subpanel”. We call these few appliances the “critical loads”. They are usually refrigerators, microwave ovens, stoves and gas ovens, electric gates, internet routers, alarm systems, medical appliances, and a few plugs around the house. However, keep in mind that the more appliances you choose to add to the list of critical loads, the bigger the capacity for the battery and then, the more money it will cost. Also, note that HVAC systems and electric ovens are not recommended as critical loads because their ignition power can be higher than the power output of the battery.

Main equipment of a battery backup system

With the wildfire season coming up in California and the likelihood of such unstable and uncontrollable events happening more often, more and more Californians are considering investing in a battery backup system. Indeed, with the current climate and dryness in the state, 2021 is predicted to be a very active fire season according to the LA Times. Additionally, in case of intense heat and fires, Southern California Edison (SCE) and the Pacific Gas & Electric Company (PG&E) have implemented new power shutdown rules in order to limit fire risks (SCE rules, P&GE Wildfire Safety Program). With the availability of energy becoming more unpredictable, a battery system will ensure that one’s home remains comfortable. Being resilient becomes even more important for people relying on electric medical appliances or people with breathing issues and more vulnerable populations like the elderly and youth groups, who will want to be able to keep an air filter functioning if needed.

Batteries can help solve the “Duck Curve” and improve one’s environmental footprint

On a more macro level, having a battery backup system can also greatly help solve the issue of the Duck Curve. This concept is defined by the peaks of energy needed at certain times of the day (early in the morning such as before work, and later in the evening after work). Since solar panels generate most of their energy when the sun is shining throughout the day (10am-4pm), those peak hours before the sun shines and after it sets are causing some stress on the utility grid due to an excess of demand. When a large number of people are using their appliances at the same time, the utilities need to provide a greater amount of energy. This greater need causes them more stress on their schedule and increases their environmental impact. Indeed, as utilities are overusing the gas plants to compensate for the drop of solar energy after the sun sets and when people usually get home, the amount of CO2 released by those plants becomes greater. A battery system can then solve this duck curve problem as it will store the energy produced during the day and feed it to your appliances during peak hours. This solution will decrease the energy generation needs from the utilities, and then help decrease their environmental impact. Without storage, we still heavily depend and rely on natural gas, and the demand for energy will not decrease; storage then brings an environmentally friendly solution to our fossil fuels reliance problem.

Image from Brighten Solar Co.

Battery backup helps you optimize your energy consumption and saves money

Additionally, your battery system can be a great way to save money by using Time Of Use (TOU) management. This method of TOU is the rate plan used by utilities since 2019; prior to that date, utilities were using a rate plan known as the tiering system. In a tiering system, the energy rates were based on the amount of usage rather than on the time of usage. Under TOU, the electricity cost varies throughout the day (variations set by the utilities). When you go solar, you are automatically enrolled in a TOU rate plan, you are then able to control at what time you would like to use your energy, thus at what price. Therefore, you are incentivized to control when you are using your energy, as the rates fluctuate throughout the day. The battery makes this process a lot easier, as many of them are programmable, allowing you to use your stored energy when the price of the energy from the utility is high. For commercial applications, it also helps resolve the issue of demand charges; or the fee charged by the utilities when a business is stressing the grid by asking for too much power at a specific time. TOU management is one of the great benefits of having a battery backup system, a great way to save money and adapt to the utilities’ ever-changing rates.

Image from Brighten Solar Co.

Watch out though, all batteries are not equals

However, when choosing to pair a solar system with a battery backup system, it is important to choose the right battery and understand that not all batteries are made equal. Brighten Solar Co. chooses to install batteries that use Lithium Ferro-Phosphate (LFP) chemistry. This particular chemistry is a lot safer and has a longer lifespan than Lithium Nickel Manganese Cobalt (NMC) chemistry. Indeed, NMC batteries are more susceptible to fire if overcharged. This condition is called “thermal runaway“: when overcharged excessively, the cells inside the battery get hot. Then, even if the charging is stopped or if it is disconnected, the temperature continues to rise on its own, and that can result in a fire. The fire can even re-ignite on its own a few days later due to the internal damage which has occurred from the overtemperature condition. Besides, Cobalt is one of the worst ethically mined minerals on the planet, with 50% of its extraction done in the Republic of the Congo mostly by children. Lastly, NMC batteries have a lifespan of 5 to 10 years when LFC batteries have a lifespan of 15 to 20 years. So even if the price tag of an LFP battery is usually higher, it will last much longer and the cost per kWh is actually cheaper than with NMC batteries.

At Brighten Solar, we choose to work with Sonnen and Enphase batteries, which are LFP batteries, that are safe, do not use Cobalt, have a longer lifespan, and are 100% recyclable!

Conclusion

Overall, pairing your solar system with a battery backup system will help you become more resilient by being less vulnerable to power outages, will help you save money through Time Of Use management, and help solve the duck curve. It is also important to get information on the kind of chemistry batteries use in order to keep one’s home safe.

Finally, remember that a solar system alone cannot function in case of outages. Only a battery backup system will keep your appliances running in case of a power outage.

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