Important Considerations for Energy Storage

santa barbara solar panels

At a time when California is setting record-breaking climate standards, our utilities are changing their rate structures, and new technologies are buzzing on the news, one thing is clear: renewable energy paired with storage is the way ahead. Are you wondering where to begin?

Batteries are an important investment for a home or business, and navigating through the nuances of new technologies with a variety of prices and features can be overwhelming. At Brighten Solar we have put a lot of time and effort into gaining expertise on the battery storage systems available because want to be sure that the systems we sell are safe and the best possible investments for our customers. If you are considering batteries, we want you to be aware of the most important features to look out for.

For a 101 course on batteries, check out our introduction to batteries blog or download our free white paper.


Anything that is installed in your home needs to come with a strong guarantee that it will keep you and your family safe. Lithium ion batteries are generally safe, especially when compared to alternatives like lead acid batteries or diesel generators traditionally used during power outages. However, the chemistry of different lithium ion batteries can cause some to be safer than others. We did some research to compare two major battery chemistries: Lithium Nickel Manganese Cobalt Oxide (NMC) and Lithium Iron Phosphate (LFP). Most home batteries on the market use one of these two chemistries. While LFP batteries tend to be slightly larger in size, they have major safety advantages over NMC.

home energy storage battery
What goes on inside your battery matters.

The most important factor in battery safety is the risk of thermal runaway. This is when batteries short-circuit and heat up so fast that they catch fire. Batteries with cobalt in them risk thermal runaway while LFP batteries’ chemistry make this virtually impossible under normal conditions.

Avoidance of thermal runaway is not the only safety feature of ferrophosphate batteries. LFP batteries are also landfill safe, contain no toxic elements, do not require cooling or ventilation, and can operate safely in a wider temperature range than NMC batteries.


Price is an obvious factor when considering a large investment into a home battery system. It is easy to compare the sticker price of different brands, but those numbers may be misleading. When considering price, it is important to evaluate the actual amount of storage you are able to take advantage of as well as the longevity of the system. Battery systems degrade naturally over time, but a system that retains its capacity longer and delivers you more electricity throughout its lifetime is more valuable. LFP batteries are more expensive up front, but are more price competitive once their slower degradation is taken into account.

There are other features of different battery systems that may be lost when only comparing the price. For example, most battery systems have the capability to minimize time-of-use electricity costs: they can be programmed to know when electricity costs from the grid are high and can begin discharging to avoid a steep electric bill. The way these systems are implemented can vary between different brands. For example, the Sonnen batterie is an all-in-one system that does not require purchase of any additional equipment, while many other systems do. Sonnen also includes smart software that learns your consumption habits and adjusts the times that your battery discharges and charges to keep your bill as low as possible. Some companies place a higher emphasis on the durability of their systems. Batteries like Simpliphi are designed to withstand harsh outdoor conditions and can also be incorporated into off-grid systems. These features provide hidden value that are worth considering when investing in a battery system that suits your needs.


A strong warranty gives a baseline understanding of what your system’s performance will look like over its lifetime. It also gives a level of assurance that you will be able to depend on the system while the warranty is in effect. Battery systems usually come with a 10 year or 10,000  cycle warranty. The important factor to notice in warranties is the guaranteed capacity after those 10 years (or cycles) are finished.

Batteries will degrade naturally over time, but to different degrees based on their use, chemistry, and quality. Simpliphi currently has an industry-leading warranty, guaranteeing 80% capacity in your battery after 10 years or 10,000 cycles. Sonnen and Tesla guarantee 70% capacity, however it is worth noting that the NMC chemistry of the Powerwall is known to degrade more quickly.


Different battery chemistries can also raise serious ethical issues with the sourcing of their materials. NMC batteries contain cobalt. This element is useful for making batteries energy-dense, so that lots of energy can be stored in a small battery like in your cell phone. Unfortunately there are big issues with the supply chain of cobalt: more than half of the cobalt mined around the world comes from the Democratic Republic of the Congo. Political instability and corrupt governments have lead to the mistreatment of the country’s natural resources and ecological abundance. Cobalt exposure is toxic to humans, but many miners in the Congo use only hand tools and have little, if any, safety equipment. There have also been many reports of child labor used to mine the toxic substance. These issues make the use of cobalt in our electronics dubious. On top of that, it is very difficult for a company to guarantee that its supply chain does not source cobalt from Congo. See our blog post about cobalt for a more in-depth look at the issues surrounding its use.

Brighten Solar Co’s Choice

After considering all of these factors relevant to energy storage systems, as a company we needed to decide what types of batteries we feel are the best, safest solutions for our clients. Once we discovered the safety disadvantages, ethical dilemmas, and faster degradation, we have decided the lower cost of NMC batteries is not worthwhile for our clients. After extensive research, we have decided to be a cobalt-free battery installer and prioritize battery systems that will last as long as possible and deliver quality electricity and backup services to our customers. To see more detailed information on specific battery systems, please request a free copy of our battery comparison chart, which also has some helpful definitions and summaries of each system.

Have a question? Please don’t hesitate to call us at 805-708-3654. We are always happy to help you find the information you need to make an informed decision.