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SolarEdge’s StorEdge Inverter and the LG Battery System: Just the Facts

From residential to utility scale, storage is one of the biggest issues in the solar world. Technologies are evolving, and there will be many changes over the coming months and years

In our area, the recent big news seems to be the SolarEdge System – StorEdge Inverter coupled with the LG lithium-Ion battery. At least three solar companies in West Virginia are attempting to sell this system to solar consumers and, after multiple conversations with prospective buyers, I’m very sure many of the customers really don’t understand all the issues involved. I also suspect that in some cases, the installers also don’t understand what they’re attempting to sell. (For example, I asked an LG support tech about how the lithium-ion batteries would respond to being primarily storage for backup power instead of regularly cycled. His answer was “Guess I need to research that.” Good idea.)

Recently, a potential customer from a co-op, who’s considering a StorEdge/LG battery system, asked me for a competitive quote. When I told him we were not installing that system at this time for several reasons, he told me, “You guys need to come out of the Dark Ages, see the light; this is the technology of the future.”

Hmmmm. Really?

Interesting, particularly when you consider the fact we guys have installed more battery backup storage systems than anyone else in West Virginia.

But this did get me to take the time to really investigate the issues. Over several days I consulted with technical folks at SolarEdge, LG Batteries, and a customer support engineer at a leading solar distributor, who specializes in battery systems.

What follows are the facts as I understand them. I try to stay with the facts as best I can. There will also be some opinions, but those will be obvious.

The System

The system we’re talking about is the StorEdge system from SolarEdge. Currently, the only battery- capable SolarEdge inverter model is their 7600-watt model. This is basically the popular SolarEdge 7600 inverter with additional firmware, electronics and a transfer switch to allow it to interact with the battery system and a critical loads panel when the grid goes down.

The original release was designed to let StorEdge work with both the Tesla Powerwall and/or the LG 10 kWh battery system. The DC version of the Tesla PowerWall 2 system crashed and burned (not literally, as far as I know), leaving the LG battery system. This will currently work with only one LG battery; capability to tandem 2 batteries is supposed to be released soon. (That will be seriously expensive, however.)

The StorEdge system is designed to primarily work in one of two modes: The self-consumption mode, when the batteries engage on a regular basis to offset the need to buy from the utility. The system will also switch to backup mode when the grid is lost and a critical loads panel will be energized.

According to SolarEdge, the two typical applications for this consumption capability are:

  • Areas that don’t allow net metering (such as Hawaii and certain US co-ops). Solar power produced in excess to current loads is stored in batteries to be used later – at night, for example.
  • Areas with varied Time of Use rates. In this case, the system can be configured to supplement from the solar array’s production with battery input during certain time slots to avoid having to buy from the utility at the highest rate.

It’s very important to note that those two scenarios do not apply to our area, as long as we have one-for-one net metering. With net metering, this self-consumption capability is not a good choice for anyone. There are much better alternatives, like letting the grid store your excess PV production.

The other configuration is a straight backup configuration. In this case the batteries will engage only when the grid is lost. Then, an electronic transfer switch is engaged and the batteries energize the critical loads panel.

If you buy the StorEdge/LG system to use strictly as a backup power option, you’re not getting a good deal. In fact, I consider this system to be mediocre for a strictly backup only application based on:

  • Very high battery cost (compared to AGM storage)
  • Very limited stored capacity ( currently only 9.5 kWh useable)
  • Very limited surge capability. If you have a deep well, submerged well pump (3/4 HP or more), pay attention that that factor. Well pumps don’t react well to “brown power”.
  • Limited scalability (You’re restricted to the minimum and maximum solar array values that the 7600 inverter supports.) For larger arrays, you need a second inverter, which will not be part of the battery-based capability, by the way.
  • No integrated generator connection (for long grid outages)

The Data

This chart compares a StorEdge system with the LG battery to a Schneider XW5548 system with a 490 AH AGM battery bank. The XW5548 is their smallest model; we often install the XW6848 model, which is much more robust. The data points are taken directly from the companies’ published datasheets.

 SolarEdge StorEdge 7600 with LG 10 kWh BatterySchneider XW 5548 with 490 AH AGM Battery Bank
Max Continuous Output on Batteries5000W5500W
Surge Capacity – 30 secNot Available9500W
Surge Capacity – 10 sec7600W9500W
Switchover Time2 sec8 ms
Integrated Generator ConnectionNot AvailableYes
Useable kWh stored9.5 kWh (95 % DoD)17.6 kWh (75% DoD)
Cost (estimated retail), batteries only$6,100$4,000

Notes:

  • DoD = Depth of Discharge
  • The XW5548 is capable of surging to 7000 watts for up to 30 minutes at 25º C ambient temperature.

 

The cost information above is just for the batteries. If you were going with the 7600 StorEdge instead of a plain 7600, you’d also have to pay:

  • $1000 more for the StorEdge 7600 (versus a basic 7600 SolarEdge).
  • The cost of a step-down transformer to bring the LG battery’s high voltage down to a useable level.
  • For purchasing and installing miscellaneous electronics and hardware.

If you were simply adding an AC-coupled battery bank to a plain Solar Edge 7600, your additional costs would be for only:

  • An AC-coupled capable inverter/charger.
  • Battery enclosures. (The enclosures we install are metal.)
  • Miscellaneous electrical and hardware items and their installation.

Either way, you get much more bang for your buck buying a basic 7600 system and adding an AC-coupled battery bank. The AGM technology is rock-solar and predictable. The lithium-ion, not so much. (There’s a reason why the DC version of the Tesla Powerwall 2 was pulled from the market.)

During the tech boom in the years 2000-2002 I saw a lot of this. It’s the difference between leading edge and bleeding edge, the difference between deploying solid technologies and chasing evolving technologies. Over my more than 30 years in the tech business, and especially during almost 10 years at Cisco Systems, we did a lot of leading edge, early field trial stuff, but always in a very controlled environment. As a the owner of a small solar installation company I’m very sure our customers don’t want to put a lifetime of savings at risk just to have the newest widget, and I have no interest in asking them to. I will not be recommending any new technology before it’s been proven in the field over a considerable period of time.

Guess we’ll stay in the Dark Ages a while longer 🙂

As for why some solar companies are pushing this particular system, I don’t know. You’ll have to ask them.  

Solar Systems and Storage – What you need to know

 

If there’s more common buzzword in the solar industry today than storage, I don’t know what it would be. As is the case with many terms in the solar world, storage can mean different things – depending on who’s using it.

In its most basic use, storage means electric potential stored in a battery using a wide variety of chemistry, until presenting a load to the stored potential activates its power. For example, when you start your car, the electrical system presents a load to the battery, and the starter’s engaged.

When using the term storage within the discussion of solar energy it can get really confusing to the consumer. I tend to narrow it down to three typical applications (my terms) that actually exist at this point in time.

  1. Off-grid, when the batteries are the most fundamental part of the house electrical system. If the batteries are exhausted, you’ll either be in the dark or running off a generator system.
  2. Grid-tied with battery backup, where the battery bank mostly sits idle unless grid power is interrupted. Then the batteries engage, the inverter taking power from them and energizing a critical loads panel. You’re then operating as an off-grid system until grid power is restored – a two-mode (bimodal) system.
  3. Consumptive storage. This configuration is becoming very common in places like Hawaii and in many countries where electricity’s expensive and there’s no Net Metering (where the power company must accept all excess power from your array and credit you on a one-for-one kWh basis).

We’ve discussed off-grid systems on our website, so let’s look at systems 2 and 3 above.

A grid-tied, battery backup system (bimodal) is our favorite solar system, and I believe we’ve installed more of them than anyone in the region over the past 4 – 5 years. I know for a fact that we have dozens of systems installed and operational in the four-state region we serve.

As for the longevity of the batteries, we recently conducted a controlled load testing of a nearly 8-year-old AGM (Absorbent Glass Mat) battery system, and it showed almost no degradation of the battery bank. This test was conducted as part of an estate sale, and DEKA engineers confirmed our captured data. We’re expecting at least 10 years for the Made in USA, DEKA AGM batteries we use and have data to support that claim.

If properly and professionally designed and installed, bimodal systems provide years of trouble-free service and great peace of mind for the owners. In conjunction with an auxiliary generator system, they can provide the potential for months of electrical service in the event of a major loss of grid power. Some of our customers are preparing for this possibility.

A consumptive storage system is a different animal entirely. In this configuration, the solar array first services the house loads, then diverts excess power to be stored in batteries. When the array output doesn’t meet house loads (at night, for example) the batteries provide power to the house. One problem with this configuration is that it obviously demands batteries that can stand up to many cycles of charges and discharges (cycles). Another, really big, problem (to me) is that if the house loads are met, and the batteries are fully charged, the excess solar production is lost.

The consumptive solar system looks attractive to many, but the fact is that Net Metering, as long as we have it, is better by a wide margin.

If Net Metering goes away, then, like in Hawaii, consumptive storage will become the system of choice for many solar owners. We’re not there yet – and, by the way, neither are the battery systems needed to deliver a realistic return on investment or real work capability. If you don’t believe me, try to buy, and have delivered, one of the new Tesla Powerwall-2 DC systems. At some point other technologies like Lithium-Ion will probably be the answer, but not today.

By the way, the power companies are constantly challenging Net Metering – locally and throughout the country. I truly worry that if they influence enough politicians, Net Metering could be lost.

At this point, many of you may be wondering: If all this is true, why are some solar companies pushing customers to consider one of the latest and greatest storage systems based on cycling battery technologies, like lithium-Ion, instead of more mature and proven configurations like a bimodal system using AGM batteries.

The truth is I really don’t know for sure in every case, but I do know that potential solar consumers are being lobbied by solar salespersons with minimal or nonexistent battery system experience, understanding and credentials, and some customers are making some unfortunate purchase decisions.

Some of the battery system proposals we’ve been asked to review are both technically and economically incorrect – massively incorrect. Battery-based solar systems are substantially more complicated than typical grid-tied systems, and no place for on-the-job learning at your expense (and peril).

Do your own research. Ask for reference installs. Talk to existing system owners. Then, I invite you to give us a call or fill out a web page contact form for a free professional consultation and proposal.

Before you buy a solar system, ask the installer these questions:

There’s only one reason I can think of why anybody would take on the serious safety and long-term production risks of having an inexperienced installation company, or one using a group of trainees, install their solar system. That reason is, they may not  know what to ask about, besides price. And when safety and structural integrity are on the line, cheaper isn’t better.

Most non-micro solar systems operate at very high DC current flow and voltages (some as high as 1000 volts DC). Adding batteries takes the installation to a whole other level of complexity. The design and safety issues involved are real and not, in my opinion, a good place for a class project or on-the-job training at the homeowner’s peril.

And while a master electrician license requires knowledge and experience, the license alone doesn’t make someone truly qualified to design and install solar systems. There’s lots more to it than what’s covered in the National Electric Code book or the master test. (I’m sure of that because we have two master electricians on our team, and I’m very familiar with every edition of the NEC Book published since 2005.)

That’s only one part of a solar installation project – and the reason most authorities having jurisdiction (AHJs) require a building permit as well as an electrical permit.

So in addition to pricing, licenses and components, you should also ask potential installers about track record, references from previous projects, solar experience and certifications.

Probably the best question you can ask is whether someone who’ll be working on your installation has earned North American Board of Certified Energy Practitioners certifications. Their PV (PhotoVoltaic) Technical Sales and PV Installer certifications are tough to get. That’s because NABCEP is the only organization that tests for and credentials every aspect of grid-tied, off-grid and battery backup solar installations – design, mechanical issues, electrical issues, optimized production issues, installation and maintenance. (Please don’t confuse this with NABCEP’s Associate certification, which is an entry-level program; Associates must work under a senior installer, hopefully with full NABCEP certification.) You can check which, if any, NABCEP certifications an installer holds here.

Continue reading “Before you buy a solar system, ask the installer these questions:”

Questions You’ve Been Asking

Here are two questions people keep asking us:

1. It looks like many homeowners are getting solar systems with storage or battery backup. Our system doesn’t have batteries. Can we add them now?

Adding batteries to most existing systems is no problem. The configuration we’d likely use is called AC Coupling, and it’s fully compatible with all kinds of systems from micro inverters like Enphase to string inverters like SMA. The technical working of this connection is pretty far into the weeds, but we’d be happy to discuss and provide a quote to anyone interested.

2. We’ve noticed solar co-ops springing up in Virginia and West Virginia offering discounted pricing. Is that possible? Do you do co-ops?

Answering the last question first, while you should never say never, I will say it’s unlikely we’ll ever bid on any co-op offerings. I used to think that co-ops were a good thing because they promoted the growth of solar to many homes in an area. But now, based on some of the recent installer selections and direct experiences with members of multiple co-ops, I have concerns – about the installer evaluation process, about member expectations management, about co-op members’ protection. So we’ll opt out for now.

One thing I know is that co-ops have reined in their deep discount claims. West Virginia Sun, for example, used to claim 20-25% discounts. Today, they’ve changed their name to Solar United Neighbors and are more modestly claiming that “Co-op members leverage bulk-purchasing power to get discounted pricing and quality installations…” But, having been in the solar business full-time since 2009, I also know that no reputable installer can offer “discounted pricing” on a quality solar system and pay a co-op hundreds of dollars in fees per installation and make a fair profit. Real-world margins just aren’t that big. So what you may get for your “discounted pricing” is a cheaper system, based on cheaper components, a new (and less qualified) installer looking for work, and/or cheap and unskilled labor. But that’s a not “discounted pricing.” It’s a cheaper system, and you get what you pay for.

As for the “bulk purchasing power,” in my opinion that’s a fairy tale. The number of systems that co-ops deal in is far from bulk, and installers of any size already get best-tier prices from suppliers.

I always recommend that co-op folks get at least one alternate bid from someone besides the co-op committee’s selection. You’ve got nothing to lose, and when you compare apples-to-apples quotes, you may be pleasantly surprised.

Lots of Virginia and West Virginia families in co-op areas ended up liking our proposal better than the co-op installer’s proposal. Despite the supposed “discount pricing,” we’ve usually been more than price-competitive. Not having to pay a co-op hundreds of dollars per job helps. So does the fact that we always show up with a very experienced, very professional crew, supervised by highly qualified people.

 

How would you feel getting electricity for the first time ever?

 

You’d probably feel as happy as the residents of Lingshed, India, high up in the Himalaya Mountains, where electric grids can’t reach.

Engineers volunteering for the IEEE’s Smart Village project installed off-grid solar arrays with battery backup, providing dependable electricity around the clock, day in and day out.
himalayas

What works at the top of the world works even better in your part of it.

Get ready for more West Virginia snowfall (and more outages) this winter

 

 

 

Meteorologists are predicting a colder, snowier 2016-2017 winter, thanks to a weakened La Nina.

According to thewinterforecast.com

La Nina is here but it’s on the weaker side as of September. We see this weak La Nina to peak now but get a second burst in December and January before moving to a neutral pattern February and March. This weak La Nina means a colder winter for most of the nation and certainly much colder than last winter.

A weak La Nina, they add, typically brings the above normal snow for the area.

In the West Virginia area, snowfalls are predicted to be 10% to 15% above average, totaling as much as 71.7″ in Beckley, 77.8″ in Bartow, and 95.3″ in Elkins, for example.

As West Virginians know from often painful experience, more snow can mean more outages. That’s because as snow accumulates and freezes on overhead power lines, its weight can snap cables and topple poles – often in locations that the state’s mountainous topography and twisty roads make hard for repair crews to get to.

A Milestone Solar installation with battery backup bank is great protection from winter power outages. Unlike emergency generators,you get day after day of electric power – without flammable fuels, without toxic exhaust fumes, without moving parts to maintain or repair. And your system automatically “refuels” when the sun rises each morning. Continue reading “Get ready for more West Virginia snowfall (and more outages) this winter”

Don’t let power outages ground your business

 

 

You may not have heard what caused last week’s Delta Airlines computer shutdown that grounded 15,000 flights and stranded hundreds of thousands of travelers worldwide for more than 24 hours. It was a local power outage in the part of Atlanta where Delta is headquartered.

There’s a lesson for businesses of all sizes in this: You never know when or where a power outage can occur. You do know that when it does, it can make your business as dead as Delta’s was.

 

Your business doesn’t have 15,000 passenger flights throughout the world each day. And it doesn’t bring in $5.9 billion a year in adjusted pre-tax income. But the smaller your business, the more devastating a full-day outage can be. Continue reading “Don’t let power outages ground your business”

Why we won’t use the new Tesla battery in any Milestone systems

As of now, the Tesla Powerwall battery is a cycling system. That means it works for storing energy to be used only that night – not later on in a prolonged outage.

For areas without net metering, that might be okay, But for our area, they make no sense at all – to me at least – in the near term.

That’s the overview. Here’s a more detailed answer.

“Plug-and-Play” isn’t

 

People have asked is whether we install “Solar Kits” that some home improvement businesses and online dealers sell at good prices.

The short answer is no, and there are several reasons.

First, most of the “kits” we’ve looked at are anything but complete. Racking, grounding, disconnects, wiring, and other components are often missing. Customers are very disappointed to learn this, often after the purchase has been made – ouch!

Second, we would never recommend the components that are in the kits, and therefore we can’t support them. If we install it, we own it as a support issue going forward.

Since we install a lot of grid-tied, battery backup systems, we also field a good many calls about certain online businesses selling grid-tied, battery backup systems that they describe as “plug-and-play”. Our electricians will be surprised to learn this, because we find that even the most experienced electricians we bring on board take a number of installs to become comfortable with the technology and installation techniques we use.

If someone describes a bimodal solar system to you as plug-and-play, it’s time to move on to a qualified vendor.

Caveat emptor, my friends.

 

How well can the government protect against power grid attacks?

According to The Hill,

The threat of an attack on the nation’s power grid is all too real for the network security professionals who labor every day to keep the country safe…

One of the most fearful aspects of a cyberattack is that they can be difficult to spot, even when they are happening…

The energy sector for years has…had a mutual assistance program that kicks in during major power disruptions. Providers in unaffected areas send crews to places that have been crippled by a big storm, accelerating the work to restore power.

The assistance program could prove difficult to carry out during a cyberattack, however…

[I]t would seem that the U.S. has a rapid response plan ready to go in the event of any power grid hack.

But according to numerous cybersecurity experts, companies are mostly basing their preparations on the few case studies they’ve seen, creating the potential for gaps.

I’ve spoken to CEOs and utilities about this problem,” Homeland Security Secretary Jeh Johnson said at a congressional hearing in March. “There’s clearly more to do.”

One thing to do to protect your home from outages is to seriously consider a Milestone Solar system with battery backup bank.  Whether an outage results from snowstorms snapping overhead wires, software glitches, or an out-and-out hostile hacking attack, it’ll keep your lights on, your food fresh, and your rooms at comfortable termperature until the power comes on again.

A great AAAAAA-rated review on Angie’s list

Check out this glowing Angie’s List Review from a White Sulphur Springs, WV, customer on March 30, 2016:

Milestone Solar Consultants, owned and operated by Bill Anderson, did our install. We purposely waited 5 to 6 months before doing a review because new stuff always looks good in the beginning but what about months later? We wanted it before the winter set in and he made that happen. ALL his workers were polite, courteous and knowledgeable about what they were doing. We had the batteries and analyzers placed in our basement. There were no boxes, wiring or any trash left lying around anywhere. They even swept. They left my house better than they found it. Mr. Anderson promised a turnkey job and that’s exactly what we got. All the wiring from the outside mounting racks to the basement equipment looks like a piece of art. Their attention to even the smallest detail is second to none! Even though they are a 4½ hour drive fro us, anytime we called him Mr. Anderson made himself available to us and was ready to drive down immediately to address any concerns or issues we had even if they turned out to be unwarranted. This shows his dedication to what he is doing, and he will do whatever is needed to see both his solar system and his customer is always happy. We’ve already experienced 3 power outages with our Electric Company and didn’t even know it. The solar system’s batteries kicked in so efficiently and quickly that our digital clocks didn’t even start blinking. When the power comes back on the batteries switch back to standby without us having to do a thing. We also ran our home on just the solar system itself, going completely off the grid (in the winter) and ran everything easily for 4 or 5 days. Which is exactly what Mr. Anderson said it would do. He has the credentials and expertise to answer any questions you pose to him. None of that, “Well I don’t know. I will have to check on that question and get back to you.” Which we had with other big name solar installers. Milestone Solar came into our home as strangers and left as family. Any and ALL questions were answered by Mr. Anderson and his crew and there were a lot of them! And we know he will ALWAYS be just a phone call away if we have more questions or need him in any way. And that speaks volumes!! If you are looking to put in a Solar Array System, it would be to your advantage to have a quote from Milestone Solar. His prices can’t be beat ESPECIALLY when he uses ONLY top quality equipment and materials. We looked at many different systems from other companies but Milestone Solar stood out by miles…no pun intended 🙂

 

Adding Battery Backup to an Existing Residential Solar System

When we first started Milestone Solar, a residential solar system that featured a battery backup option was not at all common. It was mostly a cost issue, as the batteries do add substantial cost to the system. But I think it was also true that many installers did not (and probably still do not) like the extra complexity that an integrated battery backup (bimodal) capability brings to the project, so they did not promote the capability.

We’ve always liked the bimodal technology and the capabilities it brings, and have offered it as an option to customers for years now. Our installed base of battery backup systems speaks for itself.

But there are thousands of residential solar systems that were installed without batteries. This type of system, which I call a straight production system, does a great job of producing electricity on a day-to-day basis, but when the grid is down, your solar system shuts down – by design. One of my friends, an engineer in the solar industry, calls it buyer’s remorse to discover that you now want to add battery backup to your legacy solar system.

I think it may be any number of factors, to include spreading the cost over a longer period of time, a response to some of big storms that have caused prolonged power outages for thousands of homes, or maybe a response to the various threats to the grid as discussed in the book Lights Out by Ted Koppel.

Over the past few years we have been hearing more and more about a capability to retrofit legacy solar systems with batteries using an electrical design called AC Coupling. Our standard or typical bimodal battery backup system uses DC coupling and features the array, charge controller, batteries, inverter and critical loads subpanels. Everything on the input side of the inverter is DC.

As you can see on the graphic at the top from Enphase Energy, the main components in this AC Coupling design/ retrofit are the battery bank, a compatible inverter/charger and a critical loads subpanel. On a day-to-day basis the solar array and, in this example, micro inverters, are sending AC power to the critical loads panel. Any excess is sent on to the new inverter/charger to be routed to the main panel for use in the house, or sent back to the grid for credit via the bidirectional meter. But when the grid is down, the inverter/charger begins supplying power from the battery bank, and after a short pause, the micro inverters will see a 240 VAC connection and will once again begin producing electricity.

 

One of the keys to this process is to have a fully compatible inverter/charger that is monitoring the state of the battery bank to insure that the batteries are protected from overcharging. Most use a process called “frequency shifting” to take the AC connection to the solar system out of spec, shutting down the array inverter(s) when the batteries are at a certain state of charge. Some companies are also recommending an additional inline relay to further protect the batteries from overcharging – an option worth looking into as well.

The obvious question that comes up now is, should we now abandon DC coupling for this AC-coupled configuration? In my opinion, if you are starting from the beginning, the DC coupled system design offers significant advantages, like highly efficient MPPT charge controllers with a tapered charge cycle that can be “tuned” to your individual system and also provides great battery protection.

It probably goes without saying that this is not a good do-it-yourself project for the average homeowner. But there is now more than enough of an installed base to consider AC coupling a viable and fully supported option for the many customers with legacy solar systems who would like to add batteries for when the grid is down.