Technology Energy Management
Residential Battery Storage
a core essential for today’s resilient design
By Jason Takahashi
Rechargeable residential battery storage for residential use is quickly becoming an essential component in resilient-sustainable residential design.
There is a combination of factors driving the proliferation of energy management and energy storage devices in the residential sector. Propane-powered backup generators have been used for years in areas that suffer power outages on a regular basis – weather-driven outages or homes in remote locations that cannot rely on the power grid for 100 percent electrical delivery. Battery storage devices have grown in popularity mainly due to solar power – living off the grid and reducing one’s carbon footprint have become driving factors for a solar-meets-battery delivery system.
The focus of this article is not to debate the merits of back-up generators versus rechargeable battery storage. Simply put, back-up generators are generally quite cost-effective, but rely on heavy fossil fuel usage and storage. Meanwhile, battery storage units generally require far more investment but can be charged by either the traditional grid or renewable sources and last up to 7–10 years before component (batteries) replacement.
As rechargeable battery usage becomes more common, prices will naturally come down. In the near future, local energy storage will become a standard feature of homes across the country, especially in geographical regions where climate change impacts are more readily felt. In effect, these often overlooked systems will explode as a prominent new product category.
the major contenders
Our focus for this article is a discussion of the two principal types of batteries and their particular ‘battery chemistry’ that is currently available on the market. Lithium-ion versus lead-acid.
LITHIUM-ION BATTERIES (LI-ION) are legend in our battery-powered world. Smartphones, laptops and countless other devices all utilize various forms of lithium-ion technology. For larger scale residential use, there are numerous companies supplying wall-mounted rechargeable battery stations based on lithium nickel manganese cobalt, as well as lithium iron phosphate battery chemistry. Major players Tesla, LG, Samsung and sonnenBatterie are introducing intelligent power storage at an accelerated pace.
Ballpark pricing for a lithium-ion based residential battery storage system runs approximately $10,000 for 10kWh (kilowatt hour).To put this into perspective, a 6,000 square foot home uses (approximately) 55 kWh of power per day. Therefore, a 10kWh battery will provide a fifth of your daily power needs during a power outage – or five hours (this is just a generalization – during power outages the home would be programmed to go into low-maintenance mode).
For the luxe residential sector however, homeowners who want to ensure their art collection or priceless Persian rugs are properly protected during a major climate event will require as much as 24-48 hours worth of energy storage. In the event of a power loss, these homes must be capable of powering climate control systems (like A/C) to minimize the risk of mold or drastic temperature changes capable of inflicting long-term damage to their assets. This drives up the initial investment into the $50-75K range.
The primary advantages of lithium-ion home energy storage are its weight, cost and charge/discharge rates. While not generally seen as ‘economical’, these setups specifically empower users who want to pair their power storage with a solar photovoltaic system — allowing them to charge during the light of day and power their homes via power pack at night (when electricity prices are higher). Additionally, these systems are able to charge and discharge power faster and for longer without a long term loss of battery cycles.
These new systems also provide easy-to-use remote system analysis – or more simply put, monitoring. Germany’s sonnen has recently combined its exclusive lithium iron phosphate storage known as ‘eco’, with smart breakers and enhanced software that elegantly pairs with home automation systems. This new system known as ‘ecoLinx’ is controllable via a mobile app to monitor and see real-time data on the state of your system, while even drawing on cloud-based weather information to help intelligently manage consumption according to current or approaching conditions.
The current downside of lithium ion/manganese/cobalt battery chemistries? The still unknown environmental costs.
Large scale lithium-ion battery storage is relatively new, and thus many of the environmental impacts have yet to be seen. While solar electric storage on paper helps mitigate our carbon crisis, there are additional footprints created by the production of the technology. The United States is currently one of the only major developed nations that do not have a federal lithium-ion recycling policy in place, opening recycling initiatives up for large scale export and exploitation. Since most lithium-ion batteries made for electric vehicles and home storage have yet to exhaust their charge, we have yet to see how manufacturers will responsibly recycle and restore the materials used in their products — and how much of it can truly be repurposed.
There are plans, patents and pilots in the works, but without a firm policy or pilot system in place, it is difficult to predict the initial outcomes.
As of January 2019, homeowners should expect upwards of a $40K investment (minimum) to achieve the proper kWh backup needed to ride out an outage due to a natural disaster.
In addition to environmental concerns, there are moral ones as well. Over half of the supply of the cobalt used in lithium-ion batteries comes from the Democratic Republic of the Congo, where it was revealed that child labor was being used. Similarly, a Chinese-run lithium mine in Tibet was found to be leaking lithium waste into rural environments and communities, wreaking havoc on wildlife in the remote region. The World Economic Forum’s recent launch of the Global Battery Alliance is aimed to create a responsible value chain for this emerging market – from mining to manufacture. Meanwhile, companies like sonnen are forging ahead with alternative chemistries that rely less on toxic heavy metals (like nickel and cobalt) and are generally safer, and new chemistries are being tested all the time. With a forecasted market of $100 billion by 2025, battery makers must work to ensure the safeguarding of kids, workers and communities, while promoting the creation of a closed-loop system to meet current consumer and future policy demands.
LEAD-ACID BATTERIES have a rather longer history than lithium-ion. Invented prior to the Civil War, they are the oldest type of rechargeable battery. Large format lead-acid designs are commonly used as storage devices in mission-critical applications such as hospitals, power plants, and cell-phone towers.
For residential use, one major player in residential large-scale lead-acid battery storage stands out as of early 2019: RoseWater Energy.
While lead-acid batteries themselves are generally less expensive than lithium-ion, the RoseWater Energy Hub system is different. The reason for this is simple – in addition to the actual batteries (and amount of kWh they can store) that comprise any given storage scenario, RoseWater has engineered a state-of-the-art hub that performs under all power load and power outage conditions. With military-grade lightning and surge protection and time-tested battery technology, it’s literally built like a tank.
Another difference between the RoseWater Hub and its lithium-ion competitors is that the Hub powers your home off of the battery storage 100 percent of the time. This has two significant advantages. First, all of the products in your home that run on microprocessors are being fed pure, clean power – 24/7. There isn’t a ‘power conditioner’ on the planet that can hold a candle to battery-generated, re-formed AC power.
Second, there is no switch-over from the grid (or solar) to the battery back-up when a power outage occurs. Again, this is critical when you think of sensitive, microprocessor-based devices such as computers, servers and home automation controls which can easily get tripped by a sudden change in electrical current. When power outages, spikes and surges occur, your most important electronics are protected; no uninterruptible power supply (UPS) needed.
Finally, in the event of a major outage, the RoseWater Energy Hub provides clean back-up power for days — no additional storage required.
One downside to the RoseWater Energy’s approach is lead-acid battery life expectancy. Not only do lead-acid batteries have a shorter life expectancy (7 years versus 10+ years for lithium-ion), the long term amount of battery cycles also suffer significantly once they are discharged beyond 50 percent. That being said, lead-acid replacement costs are still far less expensive than lithium-ion and are generally easier to replace due to their established presence across industries.
As far as recycling lead-acid batteries, luckily in the United States — it’s the law. The ‘Battery Act’ (The Mercury Containing and Rechargeable Battery Management Act of 1996) was established to ensure that batteries containing toxic metals like lead were properly removed and recycled. While this policy has significantly limited human and environmental exposure to lead across the country — in recent years, however, unfortunate trends show an exodus of lead-acid batteries leaving the U.S. for Mexico, where labor costs are low and regulations for protecting workers and communities are almost non-existent in certain areas.
Another potential downside would be RoseWater’s general design ethos, which is to offer only best-in-class products. They don’t make ‘entry-level’ systems, which helps explain the higher price tag. Nevertheless, if you’re going to invest in energy storage that will automatically allow you to ride out an outage for multiple days and is designed to last, the Hub is both attractive and in some cas-es essential, depending on the location and nature of the project.
Regardless of what type of present or future battery chemistry you are partial to, rechargeable battery storage for residential use is quickly becoming an essential component in resilient-sustainable residential design. As of January 2019, homeowners should expect upwards of a $40K investment (minimum) to achieve the proper kWh backup needed to ride out an outage due to a natural disaster. Keep in mind that even though a solar panel array can often come back online immediately following a storm or during overcast conditions caused by smoke in fire-prone regions, luxe residences will opt for the ability to power HVAC systems (even if selectively), and that’s where the biggest drain on power will occur.
As dramatic weather conditions and technological innovations accelerate, do your due diligence and talk to the folks at Tesla, sonnen, and RoseWater Energy to learn more about the latest rechargeable battery storage systems. The future of energy is now!