Batteries to power homes

SLAM: debunk creationism, pseudoscience, and superstitions. Discuss logic and morality.

Moderator: Alyrium Denryle

User avatar
KroLazuxy_87
Padawan Learner
Posts: 196
Joined: 2009-06-11 10:35pm
Location: Indiana, Pennsylvania

Batteries to power homes

Post by KroLazuxy_87 »

Borgholio's post Aluminum / Air battery prototype developed got me thinking about some newsy rumblings I'd heard about/from Tesla's CEO Elon Musk and a large home-installed battery to be announced at the end of the month. Like all things 'tech', details never wait for the planned date to start circulating.

This website and others that are mostly geared towards cars (pardon the pun) seem to be talking the most about this new offering from Tesla - makes sense since Tesla is primarily viewed as a car company.
Tesla Home Battery Details Emerge
Details about the Tesla home battery are beginning to emerge. Is that what Elon Musk was hinting at when he Tweeted a few days ago about a major, non-automotive announcement coming on April 30? We don’t know, of course, but most Musk watchers think that’s what the hoopla is all about.

According to Benzinga, Trip Chowdhry, a stock analyst for Global Equities Research, has sent a note to his investors with some details. He claims 230 California homes currently have a Tesla home battery installation and that there are another 100 in homes in other states.

Want details? OK. Here’s what one of the homeowers who claims to be testing the Tesla battery told Chowdry:

The Battery has to be installed 1.5 feet above the ground, and should have an open space of 1 ft on all sides.
The battery does not make any noise, does not need any maintenance, and has no drippings.
The Battery includes the inverter.
The battery is about 3 ft tall and 2.5 ft wide and looks good.
The installer offered a choice between a 10 kWh and 15 kWh. He opted for the 10 kWh battery.
Price for the 10 kWh battery is said to be $13,000. At present, the local utility, Pacific Gas & Electric, is offering a 50% rebate. This particular homeowner opted for a payment plan that called for a down payment of $1500 and monthly payments of $15 for 10 years. But here’s the kicker. He charges the battery at night when electricity costs are lowest and sells it back to PG&E during the peak demand times every day. He says he makes $12 – $15 a month doing that, which pretty much covers his monthly payment.

Here’s more interesting tidbits Chowdry says he learned from the Tesla battery customer:

The battery can be controlled from an iPhone, and has a web application also.
The battery is set to charge from a solar system until fully charged and then send energy back into the grid.
Fully off Grid. The battery can be charged by a regular generator also.
He has not had any problems with the Battery System…and gets over the air wireless software updates frequently.
That is all very exciting news. But be warned. Not every utility is as generous with its rebates or willing to take back electricity from homeowners as PG&E. Part of that willingness is spurred by mandates from the California government that require them to get 33% of their electrical power from renewable sources by 2020. Not every state is as focused on environmental issues as California is. And many utilities are outright hostile to home solar power in general.

In other words, as we car people are fond of saying: “Your mileage may vary. See retailer for details.”
Other news sites are picking up the story too of course, such as The Washington Post with this story. **Note: The following story at the original site has about 20 hyperlinks I didn't bother with - mostly to other WP stories. I re-linked two that were more prominently placed.
Experts: Powering your home with batteries is going to get cheaper and cheaper
In the past few weeks, there’s been a battery of new studies on batteries. Not the kind in your cellphone, but a much more revolutionary make – the kind that is already powering many cars, and that might someday help power your home.

A recent study in Energy Policy, for instance, found that the cost of batteries for home systems (to store the energy collected by rooftop solar panels) is starting to decline – although even with these systems, it probably won’t be economically optimal for most people to ditch the grid entirely. Another report by the Rocky Mountain Institute similarly found that within 10 to 15 years in some places, the most economical choice for home energy could be a solar plus battery system, meaning that there could be a great deal of “load defection” from the traditional electricity grid.

Finally, a new study in Nature Climate Change documented that there has been a steep decline in the cost of lithium ion batteries for electric vehicles like Teslas – 14 percent per year plunge since 2007.

All of which is being hailed as pretty revolutionary. “Solar-plus-batteries is set to begin a dramatic transformation of human civilization,” wrote Bloomberg commentator Noah Smith recently, commenting not only on the declining price of batteries for electric vehicles, but also the potential for more batteries in homes.

But there’s a need for caution. People with home battery systems paired with solar panels certainly exist, but are quite rare for the moment. One problem is that right now, there just aren’t many ways to make a home energy storage system investment pay off.

So why do some analysts nonetheless think that solar plus battery systems could become quite prevalent in homes, and maybe sooner than we think? Here are some reasons:

1. Cost declines for solar are already a done deal. Batteries could be analogous.
The first reason is that rooftop solar has pretty much already arrived. The Solar Energy Industries Association found that rooftop solar grew by over 50 percent in each of the last three years (2012, 2013, and 2014), and a new report from Bloomberg New Energy Finance forecasts record growth for the market in 2015.


In-home batteries are definitely a lot further off for most people, but many analogies have been noted. The recent Energy Policy paper observes, for instance, that “it is anticipated that battery technology may follow the rapid downward price trajectory of PV [solar photovoltaic] as manufacturing scale increases.”

“Storage is kind of 10 years from where PV is today,” says Bodhi Rader of the Rocky Mountain Institute. “It’s along that same trend, and there’s constant innovations being made, but there’s still a bit of a battleground over what might be the technology or the chemistry that wins out.”

2. The utility industry is taking this seriously.
The Rocky Mountain Institute report makes the case that the home solar plus battery combo, when it arrives, may challenge the traditional business model of many utilities. And is worth noting that voices from the industry itself have shown some concern.

In 2013, for instance, the Edison Electric Institute, the utility industry trade group, published a report on “disruptive challenges” to the industry, which noted:

…one can imagine a day when battery storage technology or micro turbines could allow customers to be electric grid independent. To put this into perspective, who would have believed 10 years ago that traditional wire line telephone customers could economically “cut the cord?”

Or listen to David Crane, the CEO of energy behemoth NRG, who says his company is headed “down the path towards a distributed generation-centric, clean energy future featuring individual choice and the empowerment of the American energy consumer.”

3. Tesla as the potential game changer.
Perhaps the biggest driver of battery enthusiasm, though, is the company that already sells sleek battery-powered electric vehicles – Tesla.

Not only has Tesla seen the cost of vehicle batteries decline, per the Nature Climate Change study cited above. That could be just the beginning, once the company, teaming up with Panasonic, opens its battery-building “Gigafactory” in Nevada.

[The gamble on Tesla’s gigafactory in the Nevada desert]

The company says this will further drive down battery costs – and thus, electric vehicle costs. And this could then spill over to home batteries as well. “Consumer electronics and EV, they’re the two industries that have been making storage economical,” said Bodhi Rader, “and continued consumer adoption in these related industries is going to continue to drive cost reductions.”


There is also a sense in which Teslas represent a kind of proof of principle for in home batteries. “It’s actually a lot easier to put it in a house than in a car. In a stationary application, weight doesn’t really matter that much,” said Peter Lilienthal of Homer Energy, which co-authored the Rocky Mountain Institute report.

Finally, there’s much talk about Tesla’s plans to introduce a home battery unit. If there’s anything like the amount of attention to such a product as there is currently to Tesla’s vehicles, then that adds another major, if somewhat more intangible factor – coolness.

[This new Tesla battery will power your home, and maybe the electric grid too]

The Rocky Mountain Institute’s Rader notes that in this case, people might be willing to pay quite a lot of money for home batteries, even before prices come down to levels where it would be “economically rational” to do so, in light of the expected return they would get on their investment (in the form of lower electricity bills).

“If companies can start presenting that coolness factor,” he said, “that I think would change the conversation completely.”

Such, then, is the optimistic case.

Lest we get too far out on skis, though, let us once again note that there are still many concerns and uncertainties. First, there are plenty of Tesla skeptics out there, including one commentator at the Energy Collective who noted,

Selling batteries to homeowners is not going to be easy. There’s a good reason why so few of us have large battery banks in our homes, and it’s not because there aren’t any for sale. Batteries are expensive, and the advantages they offer homeowners are few. The majority of homeowners with PV panels get most of the benefits of batteries by hooking up their panels to the grid at little or no cost. For homeowners without solar panels, the grid in most locations is sufficiently reliable that there’s little to gain from having battery backup. If Musk is going to sell those customers batteries, he’s going to have to sell them much more cheaply than current prices, and it’s not clear that a 30 percent cost reduction is going to be enough.

And besides technological pessimism about batteries themselves — or about whether their costs will come down enough to make them a viable option for most homeowners — one key question involves what a profusion of batteries does to the electrical grid.

The Rocky Mountain Institute report notes that widespread adoption of solar plus battery systems in homes could be a blow to grid upkeep. The reason is that we need a huge amount of investment in the grid, and customers whose electricity loads “defect” won’t be paying as much for electricity, and so won’t be contributing as much to the cost of these infrastructure improvements.


Basically, if utilities make less money because customers pay them less, then utilities may invest less. And a grid that’s less modernized could be less reliable.

But there’s also an argument that this trend could help with strengthening the grid. First, in addition to going into homes, much larger batteries could help back up the grid itself. James Mandel, of the Rocky Mountain Institute, noted that batteries could “do a lot of balancing and grid management services more cheaply.”

Moreover, added Homer Energy’s Lilienthal, solar plus battery homeowners might actually be able to help the grid in a crisis by temporarily ceasing to draw power from it. After all, at a time of power outage, they’d presumably still have charged home batteries. “When the grid can’t handle the demand, they could drop off,” said Lilienthal.

He added, though, that this might require putting these homeowners on what he calls an “interruptable rate,” meaning they’d be charged less for power from the grid but with the understanding that their service might stop at certain key times.

In summary, it is a heady time for battery forecasters, and there are a lot of trends that are getting people excited. But we can only know one thing for certain about the future — that it probably won’t look like anybody’s present day forecast.
To criticize a person for their race is manifestly irrational and ridiculous, but to criticize their religion, that is a right. That is a freedom. The freedom to criticize ideas, any ideas - even if they are sincerely held beliefs - is one of the fundamental freedoms of society. A law which attempts to say you can criticize and ridicule ideas as long as they are not religious ideas is a very peculiar law indeed. -Rowan Atkinson
Cystic Fibrosis Foundation
User avatar
Darth Tanner
Jedi Master
Posts: 1445
Joined: 2006-03-29 04:07pm
Location: Birmingham, UK

Re: Batteries to power homes

Post by Darth Tanner »

The utility might be willing to subsidise this, in the UK WPD (utility for several regions) had a scheme where they installed peak shaving batteries and solar panels in several homes and schools but the scheme was abandoned as uneconomic as the actual loads of peak shaving were pretty insignificant for the investment.

From my own math in the UK market buying electricity at night on economy 7 and using it all in the day for a domestic customer using 4MWh annually with 25% night usage and a 90% efficient 10KWh battery would save £204/annually - payback of 43 years on a £8.7k install... its safe to say this battery would not last 43 years and 15,580 full charge/discharge cycles without replacement.
Get busy living or get busy dying... unless there’s cake.
User avatar
salm
Rabid Monkey
Posts: 10296
Joined: 2002-09-09 08:25pm

Re: Batteries to power homes

Post by salm »

Eh, this will take a couple more years to bring the cost down but it´s nice to see that we might have something like this in the future. Thanks to renewsables the demand for massive storage is there and people hate things like pump storages, so perhaps a distributed system with batteries in every home and/or car can do at least part of the trick.
I guess in the future they might have to reverse the pricing. Make it cheap during sunny and windy days and expensive during slow nights or something.
User avatar
Borgholio
Sith Acolyte
Posts: 6297
Joined: 2010-09-03 09:31pm
Location: Southern California

Re: Batteries to power homes

Post by Borgholio »

Regarding using batteries as backup for power outages, there would need to be a new cutoff system put in place. My house has solar, and it's enough to provide basic power to the house if there's an outage. But if there IS an outage, the whole system trips off and we get no power at all. Why? Because they don't want the panels from the residential areas keeping the lines hot if the workmen need to handle them. So they cut off entirely.

With batteries, the same issue applies. So any battery backup system for a house would need the equivalent of a computer UPS unit controller attached - able to reliably disconnect entirely from the grid if it detects grid power is down, then reconnect later. It would need to be foolproof enough that there is a 0 percent chance of a lineman getting electrocuted because some homeowner's battery is pumping juice back into the grid at the wrong time.
You will be assimilated...bunghole!
User avatar
madd0ct0r
Sith Acolyte
Posts: 6259
Joined: 2008-03-14 07:47am

Re: Batteries to power homes

Post by madd0ct0r »

Darth Tanner wrote:The utility might be willing to subsidise this, in the UK WPD (utility for several regions) had a scheme where they installed peak shaving batteries and solar panels in several homes and schools but the scheme was abandoned as uneconomic as the actual loads of peak shaving were pretty insignificant for the investment.

From my own math in the UK market buying electricity at night on economy 7 and using it all in the day for a domestic customer using 4MWh annually with 25% night usage and a 90% efficient 10KWh battery would save £204/annually - payback of 43 years on a £8.7k install... its safe to say this battery would not last 43 years and 15,580 full charge/discharge cycles without replacement.
The hope is, as smart metering becomes more common that electricity prices will be allowed to fluctuate on faster time scales - more like the stock market. Of course, some providers will continue to buy futures en-masse to offer fixed medium term prices
"Aid, trade, green technology and peace." - Hans Rosling.
"Welcome to SDN, where we can't see the forest because walking into trees repeatedly feels good, bro." - Mr Coffee
User avatar
salm
Rabid Monkey
Posts: 10296
Joined: 2002-09-09 08:25pm

Re: Batteries to power homes

Post by salm »

Borgholio wrote:Regarding using batteries as backup for power outages, there would need to be a new cutoff system put in place. My house has solar, and it's enough to provide basic power to the house if there's an outage. But if there IS an outage, the whole system trips off and we get no power at all. Why? Because they don't want the panels from the residential areas keeping the lines hot if the workmen need to handle them. So they cut off entirely.

With batteries, the same issue applies. So any battery backup system for a house would need the equivalent of a computer UPS unit controller attached - able to reliably disconnect entirely from the grid if it detects grid power is down, then reconnect later. It would need to be foolproof enough that there is a 0 percent chance of a lineman getting electrocuted because some homeowner's battery is pumping juice back into the grid at the wrong time.
How frequent are black outs where you live? The only one I can think of in the last two decades was two years ago and lasted about 15 minutes and was known in advance due to repairs. Perhaps this is going to change in the future during the shift from conventional to regenerative but at the moment I think backup for black outs is very far back on the list of reasons to get a battery installed.
User avatar
Borgholio
Sith Acolyte
Posts: 6297
Joined: 2010-09-03 09:31pm
Location: Southern California

Re: Batteries to power homes

Post by Borgholio »

How frequent are black outs where you live?
California's energy grid is not entirely reliable, especially during summer months. Rolling brownouts are not uncommon during really hot days, but Edison is actively encouraging residents to install remote-control cutoff devices on their air conditioners so they can be shut off when the grid is stressed.
You will be assimilated...bunghole!
User avatar
Me2005
Padawan Learner
Posts: 292
Joined: 2012-09-20 02:09pm

Re: Batteries to power homes

Post by Me2005 »

Blackouts are frequent in Western Washington as well, but usually because trees fall on the lines. It seems like they've been less frequent recently, but several hour blackouts once or twice a year aren't unusual even in and around major cities.
User avatar
salm
Rabid Monkey
Posts: 10296
Joined: 2002-09-09 08:25pm

Re: Batteries to power homes

Post by salm »

Is that frequent enough to be a significant enough annoyance?
User avatar
Borgholio
Sith Acolyte
Posts: 6297
Joined: 2010-09-03 09:31pm
Location: Southern California

Re: Batteries to power homes

Post by Borgholio »

It's less of an annoyance and more of a safety issue for the linemen. They expect lines to be powered down if the switch is flipped at the local substation. If a home is still powering the line, someone could get killed.
You will be assimilated...bunghole!
User avatar
Me2005
Padawan Learner
Posts: 292
Joined: 2012-09-20 02:09pm

Re: Batteries to power homes

Post by Me2005 »

PSE sends out hundreds/thousands of guys during a storm to try to get power back online quickly; putting power back into the grid would be a major hazard for everyone involved. Not to mention untrained people walking around near downed lines, which are also usually wet as the power usually goes out during the rain/windstorms we get in November-March or so.
User avatar
salm
Rabid Monkey
Posts: 10296
Joined: 2002-09-09 08:25pm

Re: Batteries to power homes

Post by salm »

Ah, no what I meant is the number of brown and black outs you have to endure a signifcant enough annoyance for you that you would pay several thousands of dollars for a battery? Lets say the safety issue for line men is solved somehow.
User avatar
Borgholio
Sith Acolyte
Posts: 6297
Joined: 2010-09-03 09:31pm
Location: Southern California

Re: Batteries to power homes

Post by Borgholio »

Ah, no what I meant is the number of brown and black outs you have to endure a signifcant enough annoyance for you that you would pay several thousands of dollars for a battery? Lets say the safety issue for line men is solved somehow.
Oh hell no. It's enough to want me to get a battery backup to protect my computer but not the whole house. The house battery would have to be dirt cheap for me to want to pay to get it installed. Either that or the difference between peak and off-peak rates would have to be enormous.
You will be assimilated...bunghole!
User avatar
Me2005
Padawan Learner
Posts: 292
Joined: 2012-09-20 02:09pm

Re: Batteries to power homes

Post by Me2005 »

salm wrote:Ah, no what I meant is the number of brown and black outs you have to endure a signifcant enough annoyance for you that you would pay several thousands of dollars for a battery? Lets say the safety issue for line men is solved somehow.
Ah, maybe. But it'd need to be cheaper and easier than a generator, as batteries have a lifespan limitation while a generator does not (by comparison). Our power can go out several times a year or not at all, and it can be off for minutes or days - so if we're going to have a backup it needs to have flexible endurance and it needs to work guaranteed every time from today to years from now. I'm dubious that a battery will last the years it'd take to recoup the investment. In California it might make sense, they buy our power when we have excess and in the summers when they're all running AC they use more than we send them, so they get rolling brownouts. Stocking up on power gradually at night might make sense for them since if everyone there did it, they wouldn't have as many brownouts.
User avatar
His Divine Shadow
Commence Primary Ignition
Posts: 12791
Joined: 2002-07-03 07:22am
Location: Finland, west coast

Re: Batteries to power homes

Post by His Divine Shadow »

We lose power multiple times a year and it's not worth anything to me to get rid of that possibility, it's not that bad really. I'd be more interested in it if I had my own power generation so I could make my own electricity and store it.
Those who beat their swords into plowshares will plow for those who did not.
User avatar
Darth Tanner
Jedi Master
Posts: 1445
Joined: 2006-03-29 04:07pm
Location: Birmingham, UK

Re: Batteries to power homes

Post by Darth Tanner »

Yes the main advantage of home battery use is if you have domestic solar so that you can store your generation that would be exported and use it instead as you would near triple the value of the energy by doing so compared to the export rate most people get.
Get busy living or get busy dying... unless there’s cake.
User avatar
biostem
Jedi Master
Posts: 1488
Joined: 2012-11-15 01:48pm

Re: Batteries to power homes

Post by biostem »

These batteries would also pair well with home wind turbines, (assuming your property is free of wind-breaking obstructions and/or your town ordinances allow you to put up the towers/masts for said turbines).
Sky Captain
Jedi Master
Posts: 1267
Joined: 2008-11-14 12:47pm
Location: Latvia

Re: Batteries to power homes

Post by Sky Captain »

13 000$ is a lot of money for 10 kw/h battery. Here I can buy 12 volt 100 amp hour deep cycle lead acid battery for 120 euro. It would take 10 such batteries to store 10 kw/h. Some charge/discharge control electronics also would be required. I think for around 2000 euro I could set up similar system from already available off the shelf parts.

I could get 13 000 $ for high performance car battery, but for house battery weight and size don't matter so cheapest battery that can get the job done would work just fine.
User avatar
Sea Skimmer
Yankee Capitalist Air Pirate
Posts: 37390
Joined: 2002-07-03 11:49pm
Location: Passchendaele City, HAB

Re: Batteries to power homes

Post by Sea Skimmer »

Lifespan matters. Car batteries are never high performance in that respect, nor are most other batteries whatever the type they might be, because its just really expensive to make batteries that don't rapidly decay under constant cycling conditions. You need high purity and high precision and some careful design details. Automotive batteries are only intended to last a couple of years, while the batteries sold specifically for solar power rigs for houses are more typically rated for 10 or 15 years of lifespan with moderate degradation. That's why the cost difference is so high.
"This cult of special forces is as sensible as to form a Royal Corps of Tree Climbers and say that no soldier who does not wear its green hat with a bunch of oak leaves stuck in it should be expected to climb a tree"
— Field Marshal William Slim 1956
User avatar
The Duchess of Zeon
Gözde
Posts: 14566
Joined: 2002-09-18 01:06am
Location: Exiled in the Pale of Settlement.

Re: Batteries to power homes

Post by The Duchess of Zeon »

I'm really confused, most household backup generators in rural areas have exactly that kind of safety cutoff already... Why can't you just install one for your solar panels?
The threshold for inclusion in Wikipedia is verifiability, not truth. -- Wikipedia's No Original Research policy page.

In 1966 the Soviets find something on the dark side of the Moon. In 2104 they come back. -- Red Banner / White Star, a nBSG continuation story. Updated to Chapter 4.0 -- 14 January 2013.
User avatar
Borgholio
Sith Acolyte
Posts: 6297
Joined: 2010-09-03 09:31pm
Location: Southern California

Re: Batteries to power homes

Post by Borgholio »

The Duchess of Zeon wrote:I'm really confused, most household backup generators in rural areas have exactly that kind of safety cutoff already... Why can't you just install one for your solar panels?
You can, its just way more expensive and requires more permits. So the installation of one of these batteries will not be cheap.
You will be assimilated...bunghole!
User avatar
The Duchess of Zeon
Gözde
Posts: 14566
Joined: 2002-09-18 01:06am
Location: Exiled in the Pale of Settlement.

Re: Batteries to power homes

Post by The Duchess of Zeon »

Bah, I think you're overestimating it. Propane generator for the family spread was not hard to get permitted at all, and Washington isn't substantially more permissive than California in that regard. Work took a licensed electrician a single day. We used to have about a minimum of two weeks a year without power due to the spring storms that would roll through snapping trees and taking it down for a day or two with perfect regularity before they finally completed a backup line when I was 12 - 13 or so.
The threshold for inclusion in Wikipedia is verifiability, not truth. -- Wikipedia's No Original Research policy page.

In 1966 the Soviets find something on the dark side of the Moon. In 2104 they come back. -- Red Banner / White Star, a nBSG continuation story. Updated to Chapter 4.0 -- 14 January 2013.
User avatar
Borgholio
Sith Acolyte
Posts: 6297
Joined: 2010-09-03 09:31pm
Location: Southern California

Re: Batteries to power homes

Post by Borgholio »

Bah, I think you're overestimating it.
Oh possibly. Whenever I asked about it, every power company guy gave me a different excuse. It was expensive, took a long time to permit, not allowed for solar-only customers, etc...
You will be assimilated...bunghole!
User avatar
Elheru Aran
Emperor's Hand
Posts: 13073
Joined: 2004-03-04 01:15am
Location: Georgia

Re: Batteries to power homes

Post by Elheru Aran »

Borgholio wrote:
Bah, I think you're overestimating it.
Oh possibly. Whenever I asked about it, every power company guy gave me a different excuse. It was expensive, took a long time to permit, not allowed for solar-only customers, etc...
More likely it's just because there's a lot of paperwork or something. That, and they don't want to have to try and keep track of which houses have cut-offs and which don't. But really it's a prudent measure, I don't see why it would have to be an issue...
It's a strange world. Let's keep it that way.
Sky Captain
Jedi Master
Posts: 1267
Joined: 2008-11-14 12:47pm
Location: Latvia

Re: Batteries to power homes

Post by Sky Captain »

Sea Skimmer wrote:Lifespan matters. Car batteries are never high performance in that respect, nor are most other batteries whatever the type they might be, because its just really expensive to make batteries that don't rapidly decay under constant cycling conditions. You need high purity and high precision and some careful design details. Automotive batteries are only intended to last a couple of years, while the batteries sold specifically for solar power rigs for houses are more typically rated for 10 or 15 years of lifespan with moderate degradation. That's why the cost difference is so high.
I looked up solar power systems sold here and price for 10 kw/h battery bank rated to last 8 - 10 years is around 3000 - 4000 euro. It is more expensive than my previous estimate, but still much cheaper than that Tesla battery is supposed to cost.
Elheru Aran wrote:More likely it's just because there's a lot of paperwork or something. That, and they don't want to have to try and keep track of which houses have cut-offs and which don't. But really it's a prudent measure, I don't see why it would have to be an issue...
I'm not sure why cut off switch should be such problem. Houses usually have manual switch on incoming line to isolate house from power grid. Power outage comes, disconnect the house from grid before operating backup system and there would be no risk of electricity from back up generator/battery going into power grid.
Post Reply