Living with Lithium-Ion Energy Storage

Insights on Integration, Operation & Performance
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The author and his new battery and the PV System
The original PV system consisted of two 1,050 W PV arrays on pole mounts and an additional 1,308 W on the power shed’s roof.
An additional 3,450 W of PV capacity were recently added on the shop roof, for a system total of 6,858 W.
The balance-of-system components now consist of the original OutBack Power 3,600 W inverters and 60 A charge controllers (left wall) and the new Morningstar 600 V charge controller (right wall).
The new Blue Ion 2.0 ESS lithium-ion battery consists of eight 48 V, 2 kWh battery modules.
Inside the rear of the cabinet is the battery management unit: the brains of the Li-ion battery.
Each of the eight 48 V battery modules contains 224 individual 3.45 V, 9.375 Wh cells.
Allona Fiero of Willpower Electric carries a 59.5-pound LI battery module with a usable rated capacity of 2 kWh.
Temperatures in the power room are monitored and have never dropped below 41°F or exceeded 88°F.
Penetrations for the battery-to-inverter cables were punched into the right side of the cabinet.
Cables were threaded through the cabinet penetrations before crimping on the ring lugs.
Kyle Bolger slides the battery modules into the cabinet­—four sit on the lower shelf and four on the upper.
Battery modules are held in place by support plates that are secured to the cabinet and each module. Horizontal busbars are installed before the final fasteners are inserted into the support plates.
With the rear panel of the cabinet removed, modules were secured to the rear support plates.
After the modules were positioned and secured, Willpower Electric’s Bruce Fiero tightened busbars and terminated the main cables that connect to the BMU.
The communication cables for each module are daisy-chained to the BMU; each module was assigned a digital address via rotary switches.
The finished battery, just needs the cabinet doors.
Two CTs and the eGauge energy monitor, installed in a wire trough, measure output on the main inverter AC lines and communicate via the site’s local area network.
With the orange safety plugs installed, the battery system is energized. Engaging a rocker switch on the BMU initiates a 10-second diagnostic and battery module-mapping startup routine.
This eGauge screenshot shows daily state-of-charge (SOC) data for the first three months of the system’s operation. As of this writing, the lowest SOC has been 15%.
he Blue Ion 2.0 system has both web-based and app-based monitoring interfaces. These app screen-captures show battery SOC information (left); weekly cycling (center); and a polar chart of 24-hour energy usage (right).

This article details my experience integrating lithium-ion (Li-ion or LI) energy storage into my off-grid homestead’s energy system, and includes design and installation considerations, plus initial performance and operation insights.Without really thinking about it, my partner Emily and I have surrounded ourselves with lithium-ion (LI) batteries at our off-grid cabin. My sports watch and Bluetooth audio speaker use LI energy storage. The Apple  devices strewn about—laptop, tablet, smartphone, and wireless ear buds—all run on LIs when disconnected from AC power. The upright and handheld vacuums both use them. Out in the shop, a half-dozen cordless hand tools share a common LI battery platform. The wireless weather-station sensors and shop alarm system incorporate LI technology. I never made a conscious decision to purchase these products based on their battery technology, but I am benefiting from and rely on the high power density and long cycle life that LI batteries provide.

LI use in home-scale energy storage systems (ESSs) is a relatively new application. Like a lot of renewable energy (RE) enthusiasts, I’d followed the LI ESS development for home-scale systems and researched how the products integrate with other RE system components. After 15 years of living off-grid with lead acid (LA) batteries, I had a growing curiosity about not only how LI technology might influence system design, but, more importantly, how it might change the way we manage energy generation and use in off-grid systems.  

In early January 2018, I installed Blue Planet Energy’s Blue Ion 2.0 16 kWh ESS at my off-grid property. Because LI installations are still uncommon in residential energy systems, I invited some local installers—Bruce Fiero and his daughter Allona from Willpower Electric, and Shawn Schreiner and Shawn Franks from True South Solar—to check out the installation. I was fortunate to also have Kyle Bolger and Jody Powell from Blue Planet Energy on site on installation day.

The Lay of the Land

Our 50-acre off-grid property is at 4,600 feet elevation in southwestern Oregon, about a dozen miles outside of Ashland. With hot, dry summers and a little less than 20 inches of annual precipitation, southern Oregon has a Mediterranean climate. Temperatures on the property range from triple digits in the summer to single digits in the winter, when the snow can pile up for several months. The site has wide-open, nearly shade-free solar access in a region with an annual average of 198 days of sunshine (4.9 average daily peak sun-hours). Even during periods of unsettled weather, we rarely experience multiday runs without at least some partial sun.

The property has slowly evolved from a simple retreat—a camp trailer, a few PV modules, and a satellite Internet dish—to a rustic homestead with a small organic farm that Emily and I began to develop in 2015. The site’s electrical loads have been variable, but always increasing, during the 15 years we’ve been on the land. Our daily energy requirement ranges from 5 kWh to more than 20 kWh depending on the season. The base electrical load includes a well pump, lighting, household appliances, home electronics, Internet networking components, and the power tools we drag out during construction phases. We use an induction cooktop, microwave, and outdoor propane grill for most of our cooking. Water heating is either electric or propane, and space heating is primarily by wood, but we also supplement with electricity and propane. Our highest period of energy use is during the long, hot days of summer when we pump water to our drip-irrigated gardens.

In 2005, I designed and installed the homestead’s core power system, which included two pole mounts each with six 175-watt Sharp PV modules (2.1 kW total); two OutBack Power VFX3648 inverter/chargers, a balancing transformer, and overcurrent devices mounted on an OutBack PS2 power panel; and two OutBack MX60 charge controllers. All of this equipment has been durable and reliable—it is still in use. I was an early adopter of using AGM batteries in an off-grid system. The original battery bank was eight 6 V, 390 Ah Discover AGM batteries (18.7 kWh total rated capacity) that lasted 11 years. We tended to be conservative with how deeply we discharged the battery bank. A typical overnight depth of discharge (DOD) was 15% to 20%, and we would take the bank down to about 50% during periods of stormy weather. 

This system ran largely unchanged for about a decade, but has been expanded over the last few years to meet the growing energy requirements of the farm. In 2016, I reconfigured the pole-mounted arrays to share an MX60 controller and added four 327-watt SunPower PV modules (1.3 kW) on the power room roof, regulated by the second MX60. Our friends at Haase Energy Systems installed a 14 kW Kohler 14RESA propane backup generator in the fall of 2017.

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Comments (10)

Robert Dee_2's picture

Thanks for the article.
I'm presently running the same basic system as you with two 3648 Outback inverters. Because I don't need complete off grid I had Outback modify my inverters (free, I paid shipping) to off grid/Intertie.
My present battery bank is 8 Rolls 530s L/A batteries that are showing their age (2006 install).
Since I have the luxury of the grid I use it to keep my bank charged and sell all my excess back to the grid. When we have power failures I run on the batteries, of course.
I'm presently building a powerwall with Lithium P04 batteries but it will be much smaller than yours since I don't rely on the system for full off grid power.

If I didn't have the expertise to build the bank I would probably get AGM's. Even though they are more costly than L/A my thinking is that the maint free aspect is very appealing.
By going one more time with AGMs or L/A batteries the cost of lithium's might come down enough to justify their use. As of now that $17k cost is in nickel/iron territory and above my dollar justification.

Jesse Roberge's picture

Lithium-Ion battery banks will displace AGM lead-acid battery banks (which have double the cost and half the cycle life of flooded), but they will not replace thick-plated flooded lead acid battery banks. They need to get much much cheaper before they can start displacing flooded lead-acid.

My current Surrette Series-4000 L-16 battery bank (two strings of 8) is still going strong. When it comes to replacement time, I'm going to the S-500EX (seriess 5000 plates in a series 4000 container, L-16). I will also be adding more solar panels but not more batteries. Shifting usage to the daytime does you a lot of good.

Malcolm Drake's picture

The cost of energy storage using this system ("For my system, the cost works out to $1,074 per kWh of storage."), like the cost of using Elam Musk's Power Wall, strikes me as being absurdly high!

Assuming the cost of grid power is around $.10 per KWh, as it is in SW Oregon, that means a person would be spending $1074 to store TEN CENTS worth of electricity.

Clearly, I’m missing something, right; it certainly wouldn’t be the first time!

Robbie R.'s picture

It does sound bad when you state it that way. On the other hand you are not looking at the long game of 22 years, also known as 8,000 cycles divided by 365 days. Compare that math to you led acid battery that would meet both the kWh and the cost and see if it is the same.
Currently LA is cheaper and the tech is easily understood because of the long history. But when comparing apples to oranges, we need to find the common ground. In this case it looks like kWh and years of service versus cost is the denominator we are looking for.

Terry McNinch's picture

Another article about this battery technology that avoids mentioning price.
Home Power magazine has credibility BECAUSE it includes system and component prices in its case study articles.
Is this an article, or an advertisement?
If it is an ad, it should state so.

Lydell Anderson's picture

In fairness to the author, somewhere mid article it mentions what this type of system might cost, but given that what sound like company representatives we're present at installation, it sounds like neither you nor I would receive the customer service and price that the author got. Add to that sections of the article that sound like they were edited carefully by a company rep (specifically the rationalizations of cost effectiveness of lithium batteries iirc), you have a classic infomercial article. Perhaps this is why Home Power is a free magazine? Have yet to see truly cost effective lithium bats for home (or RV) use.

Joe Schwartz's picture
Hello Terry and Lydell, thanks for commenting. The BPE system I'm running is an evaluation unit. I did not pay retail price for the storage system. Company reps did not review or edit the article prior to publication. Retail pricing is included in the article text. We hear from a lot of HP readers that want to learn more about lithium-ion storage in off-grid applications. My goal for the article was to share my initial experience with a new storage technology for off-grid systems. Thanks again for writing in. —Joe.
Terry McNinch's picture

Joe,
thanks for pointing out that prices were included. I went back and found 4 more pages to the article! Which wasn't expecting for an online post. Confidence in Home Power is restored.
The historic editorial honesty of the magazine is what gives it the credibility it so rightly deserves.
Yes, many of us do want to know about the new battery technologies. Still outside my price range for my small off grid system, but valuable understanding anyway. Thanks. And HP, keep up the good work.

Terry McNinch's picture

Home Power magazine is free?
Have to remember that the next time I pay my subscription.

Lydell Anderson's picture

Nice article, but reading between the lines it is not clear whether you paid full retail price out of pocket or whether this was a deal in exchange for reviewing. Lithium bats are still pricey when paid out of pocket. (I apologise if I missed your disclosure statement at beginning or end of article).

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