Energy Storage: pros and CONS.....mostly cons

[SanDiego_installer]

Pros

• Will power my entire house during a utility outage..............(sorry this is a myth)
• Will save HUGE money due to high utility time-of-use rates...............(sorry again, this is also a myth)

CONS

• Very expensive
• Will never pay for itself if used to offset high time-of-use rates
• You can't power your entire house during a blackout. You can't run your air conditioning, do laundry, cook a meal, etc. A backup loads subpanel must be installed with only a few circuits. Why? Because your expensive battery only has 9.3 kWh of usable energy, when brand new, and will degrade substantially over time.

TOU Savings Example
This is based on my local utility SDG&E. SDG&E considers peak summer rates to be in effect from June 1 - October 31, 4pm - 9pm. Let's call this 150 days of peak summer rates with a peak/off-peak differential of $0.30/kWh. Assume I have a SolarEdge inverter with one LG Chem battery. The LG Chem battery is rated at 9.8 kWh, however only 9.3 kWh is usable.
Here's the math to calculate the maximum potential summer savings:
= usable battery energy x savings differential x # days
= 9.3 kWh x $0.30/kWh x 150 days
= $418.50 annual savings in year 1

Future Savings
= $292 annual savings in year 10 if battery degrades 70% and rate differential remains the same
= $670 annual savings in year 10 if battery degrades 80% and rate differential increases to $0.60/kWh

• Winter time-of-use differential is only $0.02/kWh. You probably don't want to daily cycle your battery for 7 months to save less than $0.20/day.
• LG Chem warranty states that the battery will retain at least 60% of nominal energy for 10 years. Unlike solar panels, it does not state if this is linear degradation. Meaning you could lose 10% in the 1st year. We just don't know.
• Rates will definitely go up over time, but it will be across the board. Therefore the summer differential may increase or just stay the same.
• The local incentives in CA reduce the cost of this system, including a backup loads subpanel, from an estimated $12,000 to $6,500. However if you finance this with HERO, your total costs including interest will be around $10,000.
• At the end of your warranty, a new replacement battery is not eligible for any incentives. Don't count on huge price reductions. In fact Tesla announced a price increase in 2018 for the PowerWall, which was quickly matched by LG Chem.

[organic farmer]

Pros

• Will power my entire house during a utility outage..............(sorry this is a myth)
• Will save HUGE money due to high utility time-of-use rates...............(sorry again, this is also a myth)
  

• I do not understand why you consider it a myth that people are powering their homes with solar power.
  
  I am from California, at one time I owned a house there. But that was before time-of-use rates became a thing. I thought the idea with TOE power was to use it when it is cheap, and to not use any when it is expensive.
  
  
  
  

  ...

CONS

• Very expensive
• Will never pay for itself if used to offset high time-of-use rates
• You can't power your entire house during a blackout. You can't run your air conditioning, do laundry, cook a meal, etc. A backup loads subpanel must be installed with only a few circuits. Why? Because your expensive battery only has 9.3 kWh of usable energy, when brand new, and will degrade substantially over time.

TOU Savings Example
This is based on my local utility SDG&E. SDG&E considers peak summer rates to be in effect from June 1 - October 31, 4pm - 9pm. Let's call this 150 days of peak summer rates with a peak/off-peak differential of $0.30/kWh. Assume I have a SolarEdge inverter with one LG Chem battery. The LG Chem battery is rated at 9.8 kWh, however only 9.3 kWh is usable.
Here's the math to calculate the maximum potential summer savings:
= usable battery energy x savings differential x # days
= 9.3 kWh x $0.30/kWh x 150 days
= $418.50 annual savings in year 1

Future Savings
= $292 annual savings in year 10 if battery degrades 70% and rate differential remains the same
= $670 annual savings in year 10 if battery degrades 80% and rate differential increases to $0.60/kWh

• Winter time-of-use differential is only $0.02/kWh. You probably don't want to daily cycle your battery for 7 months to save less than $0.20/day.
• LG Chem warranty states that the battery will retain at least 60% of nominal energy for 10 years. Unlike solar panels, it does not state if this is linear degradation. Meaning you could lose 10% in the 1st year. We just don't know.
• Rates will definitely go up over time, but it will be across the board. Therefore the summer differential may increase or just stay the same.
• The local incentives in CA reduce the cost of this system, including a backup loads subpanel, from an estimated $12,000 to $6,500. However if you finance this with HERO, your total costs including interest will be around $10,000.
• At the end of your warranty, a new replacement battery is not eligible for any incentives. Don't count on huge price reductions. In fact Tesla announced a price increase in 2018 for the PowerWall, which was quickly matched by LG Chem.

Many years ago, I owned homes that had A/C. I certainly do not have A/C now.

So is most of your rant just focused on powering A/C?

[solar pete]

As an installer I totally understand his rant, I think its a good rant, as I also have to deal with customers who think they will save money and be able to run their house in the event of a blackout with their piddly little battery. Us installers get tired of educating people as to the realities of hybrid systems, sure you can run your house in the event of a black out but if you think you can run your AC while making toast and cooking breakfast and boiling the kettle in the morning when you have depleted your battery overnight you are dreaming. Look batterys are cool but it generally takes us an hour to educated people to their limitations in the real world.

[organic farmer]

We lived for a while without electricity. Then we got hooked up to grid power, and for over ten years we learned to live under the constant threat of the grid going down. So when we finally got solar power [like many of our neighbors] we were very excited to have it.

Looking back I would prefer to have a few windmills added to our system.

I think I just came into solar power from a distinctly different perspective.

Every year I volunteer as a co-coordinator to a Country Fair that focuses on organic and DIY homesteading skills, we get roughly 65,000 attendees each year. I have met hundreds of folks who have no grid access in their townships, and that get by with 600 to 800 watts of photovoltaic panels for their homes.

I suspect that your perspective is way too urban, for us to share the same outlook.

[SunEagle]

We lived for a while without electricity. Then we got hooked up to grid power, and for over ten years we learned to live under the constant threat of the grid going down. So when we finally got solar power [like many of our neighbors] we were very excited to have it.

Looking back I would prefer to have a few windmills added to our system.

I think I just came into solar power from a distinctly different perspective.

Every year I volunteer as a co-coordinator to a Country Fair that focuses on organic and DIY homesteading skills, we get roughly 65,000 attendees each year. I have met hundreds of folks who have no grid access in their townships, and that get by with 600 to 800 watts of photovoltaic panels for their homes.

I suspect that your perspective is way too urban, for us to share the same outlook.

Maybe people in Maine have a different outlook on what they need to power a home compared to people in CA or any non-rural living condition.

You certainly have my admiration for being able to live off grid. It would be hard to get my wife or any other family member to even think about doing so.

[solar pete]

We lived for a while without electricity. Then we got hooked up to grid power, and for over ten years we learned to live under the constant threat of the grid going down. So when we finally got solar power [like many of our neighbors] we were very excited to have it.

Looking back I would prefer to have a few windmills added to our system.

I think I just came into solar power from a distinctly different perspective.

Every year I volunteer as a co-coordinator to a Country Fair that focuses on organic and DIY homesteading skills, we get roughly 65,000 attendees each year. I have met hundreds of folks who have no grid access in their townships, and that get by with 600 to 800 watts of photovoltaic panels for their homes.

I suspect that your perspective is way too urban, for us to share the same outlook.

Yep, I was ranting about the Urban people we deal with 99% of the time, with big AC units, full electric houses, Pools, Spa's teenagers who live online and have no concept of an off switch, etc

[solarix]

My observation is that the general public has the notion that there is a thing called electricity. No understanding of how much of it - just that they "have" electricity. "My house has electricity - therefore, I can do all I want" They think if they put in a battery backed system, it is the same as being on grid. I have "electricity", I can do anything I want.... What do you mean I only have 4kW of power and 25kWhr/day of energy?????

[inetdog]

I do not understand why you consider it a myth that people are powering their homes with solar power.

It is not a myth that people are powering their homes with solar power. But the vast majority of them do it by using grid tie inverters, with the grid as an infinitely large free battery. Those systems are of no use whatsoever when the grid is down. It is not a myth that some people can power their home with solar power when the grid is down, but they have paid a high price for batteries and have learned to be very careful in their power consumption during an outage.
For those who have limited occasional power outages and want to use PV efficiently, they should use a pure grid tie system and add a generator to cover utility outages. Much cheaper in the short and long run.
These evaluations will slowly change as the cost of batteries comes down, but we are not there yet.

[azdave]

I suspect that your perspective is way too urban, for us to share the same outlook.

Maybe your perspective is way too rural.

Joking with you of course but understand your view. A few people think being without electric comforts for more than 30 minutes is a crisis that's worthy of spending big bucks to prevent.

[organic farmer]

It is not a myth that people are powering their homes with solar power. But the vast majority of them do it by using grid tie inverters, with the grid as an infinitely large free battery. Those systems are of no use whatsoever when the grid is down. It is not a myth that some people can power their home with solar power when the grid is down, but they have paid a high price for batteries and have learned to be very careful in their power consumption during an outage.
For those who have limited occasional power outages and want to use PV efficiently, they should use a pure grid tie system and add a generator to cover utility outages. Much cheaper in the short and long run.
These evaluations will slowly change as the cost of batteries comes down, but we are not there yet.

Every home in my town has their own generator. Our public utility grid goes down far too frequently for anyone to live here without their own generator.

Among people I know who use solar power 3 out of 4 are off-grid. Only 1 in 4 is grid-tied net-metering. I suspect that through-out New England this ratio is pretty standard. The cost of systems is purely an after thought, nobody cares. Their primary concern is having power, which the public utility is not capable of providing. One of my neighbors was showing me his fuel bills, he spends $150 a month on fuel to run his generator, it only runs during power outages.

Your area is a lot different. I do not doubt that in your area the majority of solar power users likely are net-metering.

[J.P.M.]

Every home in my town has their own generator. Our public utility grid goes down far too frequently for anyone to live here without their own generator.

Among people I know who use solar power 3 out of 4 are off-grid. Only 1 in 4 is grid-tied net-metering. I suspect that through-out New England this ratio is pretty standard. The cost of systems is purely an after thought, nobody cares. Their primary concern is having power, which the public utility is not capable of providing. One of my neighbors was showing me his fuel bills, he spends $150 a month on fuel to run his generator, it only runs during power outages.

Your area is a lot different. I do not doubt that in your area the majority of solar power users likely are net-metering.

So what's your point ?

I bet everyone here appreciates and respects your opinions and perspectives. I sure do. But it's looked to me for some time now that you live and think in a bubble.

Know this: Your lifestyle (and apparently that of many of your neighbors) is an outlier with respect to a lot of the developed world. That's far from a knock, but you often write - as now - as if everyone lives with power outages such as you do on a regular basis. Some do. Most do not, and more to the point, my educated guess is most wouldn't tolerate or perhaps more accurately be able to cope with your situation.

I think I'm a pretty typical American. Among people I know who use PV to offset or eliminate their electric bills (and for most all of those folks, offsetting their bill is usually the biggest if not sole reason for PV - separate from lifestyle demands or unreliable grid power which for most of them are rare events indeed), I know of no one personally who is off grid. Everyone I know is grid tied. I think I might know half a dozen or so folks w/generators for backup. The folks I know include a fair number who live in New England. Some of those NE'ers have PV. They are grid tied.

Seems to me, by personal contact and reading some of the apparent insanity that gets churned out here, that the acquisition cost of the systems (at least first cost) is paramount to a fault with most all those folks and IMO only a detriment to long term cost effectiveness. PV is not a matter of survival to most folks I know, hear or read of. It's usually seen as a way to not pay for something they see as not worth the price of the electric bills that go with it.

PV users usual and primary motivations are not spending what they see as an exhorbitant amount of money on something they take completely for granted, usually coupled with what they often see as a way to screw the POCO. There's also more keeping up with the Jones' than I might have once thought.

While your opinion is certainly valid, interesting and good to bear in mind, it looks and reads to me that you have closer to an off grid type of existence. To the degree that's a valid conclusion, I'd say that if you think your situation is typical with respect to most of the rest of the developed world, you're in a bubble. My guess is not everyone reading this post has something close to your situation.

My guess is few do. Very few.

[jflorey2]

[*]Will power my entire house during a utility outage..............(sorry this is a myth)

Plenty of people power their entire houses with no grid at all. I think what you are saying here is that "a small/cheap system won't power their entire house during an outage."

[*]Will save HUGE money due to high utility time-of-use rates...............(sorry again, this is also a myth)

Agree here. Further you don't need the second part. ANY battery storage system won't save you money, unless you live in a place like Hawaii with truly insane power prices.

[SunEagle]

Plenty of people power their entire houses with no grid at all. I think what you are saying here is that "a small/cheap system won't power their entire house during an outage."

...

To be honest most people would not have the room on their roof or yard for a pv array to power their entire home unless they live in a very modest building with minimal electrical needs.

If you can get away with less than 20kWh a day you might have a chance but I believe if you have A/C, electric cloths dryers, electric water heater and pool pumps you couldn't live with less then 40kWh a day. That will require a pretty big pv array unless you live in the South West but you can forget about going totally pv if you live in the North East.

[JSchnee21]

"You can't power your entire house during a blackout. You can't run your air conditioning, do laundry, cook a meal, etc. A backup loads subpanel must be installed with only a few circuits. Why? Because your expensive battery only has 9.3 kWh of usable energy, when brand new, and will degrade substantially over time."

I don't disagree. But, I thought one of the advantages of the Tesla offering was that the instantaneous and sustained kW output of multiple PowerWall units could be combined to handle larger loads without having to resort to a separate UPS load panel. Of course, buying multiple units is expensive, obviously. It's not clear to me if LG or others have a similar capability. Scaling energy capacity yes, but scaling instantaneous power -- not sure.

Yes, energy storage capacity is limited so you're not going to be able to run you AC full tilt for very long before your battery is exhausted. But, if I'm home during the day when the sun is shining, I could potentially do so for longer. And its up to me to prioritize which loads are most important to me.

Unfortunately, what you really want (if money were no object) would be a combination system which had reasonable UPS storage capacity to cover small transients and protect from surges and unplanned outages, that could take as input (automatically) the grid, solar, and a generator. But, I've yet to see a large scale (say 5 to 15kW) grid tie Solar solution, with storage, that could make any effective use of a generator. Typically, when a generator gets involved, the entire house is islanded by an ATS when its running -- separating itself from the grid and the PV/Storage system

In this way power to the loads would never run out given fuel assuming none of the equipment failed. Generators are nice, natural gas even better, but there is still an outage during the switchover and you cannot load shift.

In my case all of my larger appliances are gas (except the AC, Microwave, coffee maker, fridge, etc.) but many/most of the gas appliance still require a small amount of electric to start and run given the igniters and controller boards. So running on battery backup, sans air conditioning, for several hours to most of a day would be doable. But not inexpensive at $10-15K. A generator would be less expensive or at least equally as expensive with an unlimited run time.

[SanDiego_installer]

My "rant" was about energy storage...................i.e. batteries

I'm an installer of solar panels and have a BUNCH on my roof!!