Battery to power most of your home coming soon?

[Darwin333]

I would be more likely to do a solar setup on my roofs if I could sell back my energy to the grid though that isnt as easy as it sounds.

Actually it's very easy to do and is how 90% of US solar installs currently operate, they are called "grid-tied" systems. Most people are at work when their solar generates the bulk of its power so your meter (assuming you have enough stuff turned off) literally spins backwards as it "sells" the power back to the grid.

 

[Darwin333]

For someone who knows something about solar panels: What kinda cost would you be looking at, to say, cover, say 500sqft with panels? I'd say that would equate pretty well with decent coverage on the roof of an average home, no? I'm guessing just a couple 10x10 arrays (round it to 250, I guess) would be outside of most people's reach, even.

IIRC, last I heard was you could generate (ballpark) about a watt per square foot. So 500sqft is half a kilowatt. For...maybe 6-8 hours a day on average? Depends on weather at your location, cover from trees and structures...not to mention how your roof is designed.

So the average ATOTer could probably run two computers for most of the time he's awake, at best. One if he's gaming. 500w wouldn't run ANY major appliances, other than at idle (i.e. fridge when the compressor is off).

Energy storage doesn't really seem like the problem here.

I am a professional in the solar field and I can put an 8KW system in 500sf give or take. I'm not sure where you got your numbers from but they are WAY off.

 

[Darwin333]

I am a solar professional and to this day, other than ignorance, I have no idea why people are so intent on going "off grid". Why in the world would I want to add the complexity, additional capital outlay and the biggest issue the ongoing maintenance and replacement cost to my solar install when I can just tie it in to the grid?

My "dream" is to install enough solar to completely offset my electric bill while continuing to use the grid quite literally as my battery backup. It doesn't help in a blackout but I can buy a natural gas gennie for the very few times I actually need it for a fraction of the cost and even less upkeep, especially since I don't need anywhere near a whole house generator for those rare occasions.

I live in New Orleans and if we get hit by even a small hurricane the power can be off for a week. I have a generator that can power a large window AC unit, a TV, laptop, various chargers, some lights and a few other things. That's all I really need in an emergency situation although it would be nice if I could power the fridge too but my big ass ice chest works good enough.

I do this for a living and I can't think of a single good reason to have a big ass bank of batteries in my house. Other than very special and rare cases I don't see why everyone else thinks they need batteries. The net metering laws make sure the power cos don't screw you on what you "sell back" up until the point that you make a yearly profit (at that point you become an energy provider versus a consumer and you gotta play by the same rules the people who had been providing you juice have to) so as far as residential applications go this is, at least for the next decade or so, a non-issue concerning renewables.

OTOH, energy storage on an industrial level is another story completely. What would truly be a game changer is some sort of industrial sized bank of energy that the power cos could use for baseline leveling. That would get rid of some of the dirtiest of their generators and reduce their costs of operation. Let the grid tied solar charge up the their batteries (not accurate but just trying to make a point) and remove the complexity, upkeep, upfront and backend costs from the consumer. Most people don't clean their friggen gutters, do we really think they are going to perfectly maintain their battery banks to squeeze that extra year or two out of them and then plunk down another $10K to replace them every 15 years? For what, so you can spend more money but at least its going to big battery instead of big power?

Efficiency is the name of the game and it doesn't matter if we are talking about solar panels, inverters or capital and I can't even calculate how much more efficient using the grid is versus going off grid with batteries and other than blackouts they net the exact same results.

 

[skyking]

my proposal is never a "big ass bank of batteries" but just enough to have lighting, and send the rest of the solar to the grid as you would. having an inverter with enough power to run appliances is just silly IMO.

 

[Red Squirrel]

Red Squirrel mentioned something about a 170V DC circuit - Red, look at the video I posted earlier; though I'm not sure what the effect of a smaller current would be on the arcing.

You'd still run AC in that case, but the light bulb would be designed to run on 170vdc so instead of having a cheap SMPS in every single bulb you'd just have a rectifier and capacitor. It could be in the fixture too, maybe that's even better. This would probably be the easiest since it would not require any new wiring. Though if it could be done safely a lower voltage DC standard for lighting would be even better. 12v is probably too low to use in a house (keep in mind the same standard would probably be used in larger buildings too) due to line losses so you'd want 24 or 48 and not sure if arcing would be an issue at those voltages.

 

[Darwin333]

my proposal is never a "big ass bank of batteries" but just enough to have lighting, and send the rest of the solar to the grid as you would. having an inverter with enough power to run appliances is just silly IMO.

The inverter just converts the DC to AC, its the battery bank that needs to be big enough to run appliances.

And even just lighting, it is so much more cost effective to get a generator. If all you want to do is run lighting you can get by with a $200 generator from Harbor Freight versus adding thousands of dollars into the solar install, decreasing efficiency, adding maintenance to a system that was almost maintenance free, and by the time you actually need the batteries they could very well be degraded to a portion of the original capacity.

It just doesn't make sense on any level unless you can't, or are cost prohibited, from being on the grid.

It seems like some people just want to spend 10's of thousands of dollars to say fuck the power companies. Again, being all about efficiency, I can think of better ways to get your message across with that money than removing a single customer from their service.

 

[K1052]

I'm generally thinking a lot of the batteries coming out of the Gigafactory will find their way into localized utility scale storage instead of people's homes. Companies already build modular battery storage using shipping containers. It would be relatively easy to set up, maintain, expand, and upgrade if everything is standardized around a cheap battery pack (like what Musk is claiming the Gigafactory will make). Increasingly states are requiring utilities to build storage to counteract grid instability from rising renewable portfolio standards/penetration.

 

[Brovane]

I'm generally thinking a lot of the batteries coming out of the Gigafactory will find their way into localized utility scale storage instead of people's homes. Companies already build modular battery storage using shipping containers. It would be relatively easy to set up, maintain, expand, and upgrade if everything is standardized around a cheap battery pack (like what Musk is claiming the Gigafactory will make). Increasingly states are requiring utilities to build storage to counteract grid instability from rising renewable portfolio standards/penetration.

One area the batteries will be really beneficial is for the Tesla supercharger's. As it stands right now the Supercharger's are really the worse possible combination for a electrical grid. When a Tesla pulls into a SuperCharger you could have the power draw go from 0 to 120kw in seconds. You have a couple of Tesla's doing this at once you have a significant power spike in that area. Sometype of grid storage would help level that out.

 

[K1052]

One area the batteries will be really beneficial is for the Tesla supercharger's. As it stands right now the Supercharger's are really the worse possible combination for a electrical grid. When a Tesla pulls into a SuperCharger you could have the power draw go from 0 to 120kw in seconds. You have a couple of Tesla's doing this at once you have a significant power spike in that area. Sometype of grid storage would help level that out.

One of many good uses a standardized, cost effective, easily scalable storage system would have.

 

[Brovane]

One of many good uses a standardized, cost effective, easily scalable storage system would have.

Did a little more research on the Tesla commercial batteries. It looks like Tesla is testing a 400 kWh Commercial battery that is self contained. The batteries can be essentially dropped into place and then just connected together. If you needed say 2Mw you could just get 5 of the 400 kWh building blocks if you look at the picture below you can see they are setup on a skid frame for the base, which makes shipping and setup easier. This is the Supercharging station in Hawthorne. They have two 400 kWh Tesla battery units.

 

[DrPizza]

to take advantage of solar use in the home, they need to develop DC lighting systems. LEDs are DC, and not having to convert back and forth will save energy and money. A big part of the cost of LED bulbs is the build in DC supply.
If your small loads could be DC in the home, a small battery bank/solar panels make sense.

Again, I like the idea of using solar to power your lighting systems - I think it would reduce the cost of LED lights if you didn't have to convert from AC to DC, and reduce the voltage, and rough guess - a pair of deep cell batteries would be sufficient to keep the lights on in most houses for a couple of days - no backup generator require in cases of power outages. (At least for lighting, anyhow.) But I agree (see post #28) with Darwin completely that going off-grid isn't a good idea.

As much as I'd hope we could operate a switch without leaving it half-cocked, I guess we have to design for the worst case situation.
Still, I'd like to see that experiment run at 24vdc. And at a lower voltage, a capacitor across the switch would minimize the arc, assuming it used a modern spring-loaded switch.


Not really making a case one way or the other, just thinking out loud really. We run 12vdc in cars, 48vdc in airplanes without issue. So I'd think we could make it work in a home. How do dc line losses compare to ac/dc conversion losses? Are dc brushless motors worth the added initial expense compared to ac motors?

Out of curiosity, with 24 volts or 48 volts, what gauge wire will I need for my oven, microwave, electric heater, blow dryer, etc.? (Rhetorical question.) There's a reason European voltages (double American voltages) have an advantage - you don't need as thick of wire for the same power requirements. Copper is expensive. Aluminum has the fatal flaw (quite literally in fact) that it oxidizes too easily, resulting in increased resistance at connections, which results in your trailer burning down in the 1970s.

But, for those lighting circuits - if they're wired separately from the rest of the household - and throw in your doorbell circuit & smoke detector circuits while you're at it...

 

[skyking]

that's what I was talking about. Two to four batteries, no big charge controller.

 

[Jeff7]

High efficiency solar panels run in the 30~40 volt range. Lighting loads are so small with LED that amperage and wire size really does not come into play. A 36 V battery bank would have minimal charge converting, and is not high enough to give me the DC heebie jeebies.
laptops and TVs or music systems, network gear could all run off a minimally downconverted outlet. Loads are low. DC refrigerators are also a possibility.
They are common in the marine world, and extremely efficient with the juice.
http://www.indelwebastomarine.com/i...gerators/xlarge-fridges-165-271-l/cruise-271/

That unit uses 700 watts a day! It is by no means ideal or big enough or stylish for home use, but the technology is there.
We get power outages every year here in tree country. Some or a few hours, others are days.
If my food was safe, and the light switches worked that is a good part of the comfort things we miss when the power does go down. A couple hundred AH of storage and 1500 watts of panels would do it.
Heating loads, clothes dryers and washers are not practical loads to plan on. I would have a hybrid system that would do the typical grid intertie with excess solar, and do those loads I mentioned above.

You could still use a few hundred watts on LED lighting, but it is certainly much lower than incandescent.

As much as I'd hope we could operate a switch without leaving it half-cocked, I guess we have to design for the worst case situation.
Still, I'd like to see that experiment run at 24vdc. And at a lower voltage, a capacitor across the switch would minimize the arc, assuming it used a modern spring-loaded switch.


Not really making a case one way or the other, just thinking out loud really. We run 12vdc in cars, 48vdc in airplanes without issue. So I'd think we could make it work in a home. How do dc line losses compare to ac/dc conversion losses? Are dc brushless motors worth the added initial expense compared to ac motors?

Or go solid-state and use MOSFETs. No issues with arcing there.

Did a little more research on the Tesla commercial batteries. It looks like Tesla is testing a 400 kWh Commercial battery that is self contained. The batteries can be essentially dropped into place and then just connected together. If you needed say 2Mw you could just get 5 of the 400 kWh building blocks if you look at the picture below you can see they are setup on a skid frame for the base, which makes shipping and setup easier. This is the Supercharging station in Hawthorne. They have two 400 kWh Tesla battery units.

Wow. Those are a tiny bit bigger than I was expecting.
Let's hope there's never an internal short or "unexpected complete discharge" sort of problem.

I wonder what their usable lifespan is going to be before they need to be replaced.

 

[phucheneh]

I am a professional in the solar field and I can put an 8KW system in 500sf give or take. I'm not sure where you got your numbers from but they are WAY off.

Wow. Yeah, apparently so. I dunno if I just recalled a BS number, or if maybe that was somewhere in the realm of what old solar tech could do. And/or maybe someone was approximating actual average daily output over a 24 hour period.

It looks like your number is right; 10-15w per square foot with modern, high quality panels. But how many hours per day can you actually expect to get that kind of output? A typical slant-roofed house will only get direct sunlight for, what, maybe six hours a day?

What would you say is the typical size of a home installation? From the pictures I always see, it looks like most people don't install more than maybe a 10x15' array of panels.

 

[Brovane]

Wow. Those are a tiny bit bigger than I was expecting.
Let's hope there's never an internal short or "unexpected complete discharge" sort of problem.

I wonder what their usable lifespan is going to be before they need to be replaced.

Remember, these would never be used in a residential setting. Those two 400kWh in the picture could probably supply a 2,000 square foot house for a entire month.

For usable lifespan. I suspect that it depends on how you treat them. The key is to never allow the battery to every do what is called a deep discharge, basically run it all the way close to 0. If you can say keep it in spot of 20%-80% of it's usable capacity then you really extend the life. Tesla does the same thing with the Model S batteries. The standard setting on the car, doesn't allow a full charge of the battery until you put it into range mode. Also their is a reserve built in, even if you run down to zero. This really extends battery life, so I could easily see getting 10+ years out of these batteries if managed right. With large commercial batteries like this, it is fairly easy to manage battery life because you just design it into the controller. With EV cars it is harder because some owners will not treat the battery well.

 

[Gibsons]

But you make a DAMNED fine point with that last paragraph. As relatively simple an idea as that is, it seems pretty profound, actually. I wonder what the lowest-loss way would be to store energy in a mechanical form?

I would definitely say water is out, but the same concept applies to lifting a big weight, like a giant wind-up clock. Very large weight + lots of gear reduction = profit?

Maybe a flywheel? It's been subject to some research at least.
http://en.wikipedia.org/wiki/Flywheel_energy_storage

 

[Brovane]

Maybe a flywheel? It's been subject to some research at least.
http://en.wikipedia.org/wiki/Flywheel_energy_storage

They work for about 60-90 seconds. They are used by some places to replace UPS batteries to carry the load until the backup Generator(s) come on.

 

[jpiniero]

I am a solar professional and to this day, other than ignorance, I have no idea why people are so intent on going "off grid". Why in the world would I want to add the complexity, additional capital outlay and the biggest issue the ongoing maintenance and replacement cost to my solar install when I can just tie it in to the grid?

The point is that the utilities are going to cripple net metering eventually, if they aren't already in the process to do so. Solar is pretty much dead when that happens since the cost savings would be minimal. Unless you have a battery to store the extra output of course.

 

[Brovane]

The point is that the utilities are going to cripple net metering eventually, if they aren't already in the process to do so. Solar is pretty much dead when that happens since the cost savings would be minimal. Unless you have a battery to store the extra output of course.

What will happen is we will probably see some type of basic charge being delivered to PV customers, say like $5-$10 a month. Right now somebody that is having 100% of their bill offset by Solar isn't really paying anything for the actual infrastructure costs to deliver power to their residence.

 

[DrPizza]

The point is that the utilities are going to cripple net metering eventually, if they aren't already in the process to do so. Solar is pretty much dead when that happens since the cost savings would be minimal. Unless you have a battery to store the extra output of course.

This is regulated by the government. The government's been the one who has been handing out all sorts of incentives to people for adding solar power to their houses. I don't think we're going to see a drastic 180 degree change in policy which would screw all those people over. And, since the extra available power helps the utility companies - solar is produced during the day when demand is highest, I would think that it actually helps them.

 

[DrPizza]

The point is that the utilities are going to cripple net metering eventually, if they aren't already in the process to do so. Solar is pretty much dead when that happens since the cost savings would be minimal. Unless you have a battery to store the extra output of course.

Out of curiosity, for a typical install, what percentage of the total cost is for labor/installation, and what percentage for the materials? (If you happen to know.) And, if I'm willing to use land (I have a farm) for solar, versus installing it on the roof - is it cheaper to go that route? (That would result in zero shade from trees.)

 

[jagec]

And even just lighting, it is so much more cost effective to get a generator. If all you want to do is run lighting you can get by with a $200 generator from Harbor Freight versus adding thousands of dollars into the solar install, decreasing efficiency, adding maintenance to a system that was almost maintenance free, and by the time you actually need the batteries they could very well be degraded to a portion of the original capacity.

Except for the carbon monoxide, and the noise, and the need to store stabilized gasoline (or running out if the power outage lasts more than a few days). Meanwhile, your huge solar array is sitting up on the roof being useless.

One deep-cycle battery ($150), a charge controller ($30), and a shunt from one of your solar panels, and you have a simple system which is enough to run a few CFL/LED lights indefinitely. And lead-acid batteries on float service require very little maintenance and last for years and years.

Obviously this won't keep the fridge going (whereas the generator will), but it's cheap and quiet.

 

[Hugo Drax]

I can't tell if Elon Musk actually believes his businesses will be eventually successful and that his dog and pony show is designed to bridge the time gap between now and when that happens or if he knows he is in trouble and is just praying for some sort of miracle.

Either way, stories like these are integral in the way Elon Musk's keeps his businesses afloat.

-KeithP

Hype only keeps a buisness afloat so long. I don't see Tsla stock having any value in 10 years.

 

[Brovane]

Except for the carbon monoxide, and the noise, and the need to store stabilized gasoline (or running out if the power outage lasts more than a few days). Meanwhile, your huge solar array is sitting up on the roof being useless.

One deep-cycle battery ($150), a charge controller ($30), and a shunt from one of your solar panels, and you have a simple system which is enough to run a few CFL/LED lights indefinitely. And lead-acid batteries on float service require very little maintenance and last for years and years.

Obviously this won't keep the fridge going (whereas the generator will), but it's cheap and quiet.

Newer inverters have a Secure Power Supply plug that can shut power from the panels to a separate plug when the Sun is out. The SMA Inverters I am getting for my system have a plug that can supply up to 1500w when the power is out and you have sunlight.

 

[Brovane]

Out of curiosity, for a typical install, what percentage of the total cost is for labor/installation, and what percentage for the materials? (If you happen to know.) And, if I'm willing to use land (I have a farm) for solar, versus installing it on the roof - is it cheaper to go that route? (That would result in zero shade from trees.)

The quotes I got for a recent home install on my house I did see about 20% labor cost.