What is the right home battery for me?

Lithium-ion, flow batteries, saltwater batteries, these are today's solution to home energy storage. But which technology is right for you?

When it comes to home batteries, this is the go to technology for home energy storage, and the most commonly referred to companies are Tesla, LG, and Panasonic.

Lithium-ion batteries are used in installations by some of the biggest solar companies in the USA. When you get solar installed you have the option to add a lithium-based solar battery to your installation.
For those who don't mind paying too much and waiting indefinitely, Tesla’s Powerwall is available to order for a battery solution and might be available for installation in about a year from ordering.
One limitation of lithium-based batteries is called “depth-of-discharge,” which refers to how much of the battery’s capacity can be drained at any given time. Lithium batteries can be relied-upon to provide around 8,000 charge-discharge cycles, provided the battery is not discharged by greater than 80% of its capacity. If the depth-of-discharge gets as high as 90%, the battery’s lifespan might be reduced by 25%, providing 6,000 instead of 8,000 cycles.
Still, given a daily cycle, that translates to a practical lifespan of 15 to 20 years,
if nothing else breaks. Unfortunately, most lithium-based home batteries are warrantied for 10 years or less, so you take a gamble on the continued reliability of the battery after that point.

Save with solar self-consumption
One of those benefits is ensuring that you’re the end-user of all the solar energy your system produces. Under NEM 2.0 you get paid the same retail price for any solar energy you send to the grid, but you are subject to "non-bypassable distribution charges" when draw power back from the grid. By taking advantage of battery storage, you avoid those charges when you draw from your battery storage.

Helps avoid time-of-use consumption
The second way you save money with a home battery is by avoiding the high cost of on-peak electricity under a time-of-use (TOU) billing plan. On a TOU billing plan, electricity is cheap when most people aren’t using it (i.e. nights and weekends), and more expensive when they are. Most TOU plans charge the highest prices during the afternoon and evening hours, when people are cook, watch TV, and wash and dry their clothes. Oftentimes, TOU rates vary by season, with higher prices and longer peak hours in the summer when air conditioning causes extra-high spikes in energy usage.
Here’s an example of how TOU works using past rates from Southern California Edison’s TOU-D-B schedule (subject to change, of course):
You can save money with a home battery by setting it up to charge only from electricity produced by your panels or from both the panels and the grid. In either case, the key is to discharge the battery when electricity is the most expensive. By completely removing your on-peak use, you’re effectively bringing your electricity rates down, to as low as off-peak prices if you can swing it.
Using the rates above as an example, you can charge the battery for $.13/kWh and discharge it when you would have spent $.33/kWh, you’re saving $.20/kWh during peak times, every day. Or maybe you’ve got solar panels pumping electricity out to the grid during the sunniest hours of that peak time, meaning you’re earning that $.33/kWh for your energy, even as your battery meets your home’s energy needs.
So now you know a little about how much you could see using a home battery, but how much does a home battery cost, and is it worth it? Let’s find out.
How much does home energy storage cost?

Cost of the Tesla Powerwall home battery in 2019
Tesla is one of the main competitors in the home battery space, and, outside of the solar industry, the one that grabs the most headlines. The Powerwall 2 is a 13.5-kWh battery with a 10-year warranty, and like we said above, you can get it installed by Tesla either as a standalone energy storage or along with your Tesla solar panels.
Source: Tesla
The current pricing listed on the Tesla website shows the Powerwall on offer for $5,900, plus $700 in support hardware and “$800 to $2,000” for installation. Choosing the mean of the install price brings the grand total for a Powerwall to $8,000, or about $600 per kWh.
Compare that to the estimated savings of $4,000 in ten years outlined in our example above, and you get a net of $4,000. Is that worth it to you for 10 years of battery backup in the case of an outage? Of course, if you want to run your whole house during a power outage for more than a few hours, to paraphrase Chief Brody, you’re gonna need a bigger battery. That might mean two or three Powerwalls, at a cost of around $6,600 for each additional unit.
Cost of the Sunrun Brightbox in 2019 (LG Chem RESU)
A 9.8-kWh LG home battery costs about $8,000 as an add-on to a new solar system. The one pictured below is an LG Chem RESU10 rebranded by sunrun, but it is the same thing for a higher price. brightbox-overview-new-opt
Source: Sunrun
The BrightBox is really just a re-badged LG Resu battery.

How can you get a home solar battery for less money?

California's Home energy storage incentives
The first incentive that anyone needs to know about when it comes to solar-plus-battery systems is the Federal Solar Investment Tax Credit (ITC). The ITC is a straight tax credit, meaning money off what you owe to Uncle Sam each year, equal to 30% of your costs to install a system, but the ITC only applies to the percentage of battery charged by solar.
If you had planned to charge up your battery from the grid using cheap off-peak electricity under a TOU plan, you can’t claim the tax credit for the battery.
Then there's the California rebates.
California’s Self Generation Incentive Program (SGIP)
California has long been a leader in the clean energy revolution, and though the state has by far the largest base of installed solar in the country, it’s kept up the pace when it comes to innovation with the Self Generation Incentive Program. SGIP provides rebates that take money directly off the cost of home energy storage installations, and it’s going gangbusters.
The incentives are designed to step down over time as they are used by the public, with rebates awarded on a dollars-per-watt-hour ($/Wh) basis. Here’s a table that shows the different rebate amounts organized by step:
California SGIP steps for Residential Installations (less than or equal to 10kW in size)
Step 1
Step 2
Step 3
Step 4
Step 5
Each of the state’s 3 major electric utilities—PG&E, SCE, or SDG&E—has its own incentive pools subject to the steps. The program has been going since 2017, which means some of the incentive steps have already been exhausted. Currently, SDG&E customers are eligible for step 5 incentive amounts, while SCE and PG&E customers are eligible for Step 3. When the incentives go away, prices will stabilize and we expect the cost of batteries to drop by about 20% to 30%.
This Article credit:
Stacks Image 7