Depth of Discharge under load

[Ampster]

You may find this statement is not really true.
............
After that Elon Musk offered to supply a battery.

I suspected that was probably not true. The important issue was that the Australian grid was stressed and batteries came to the rescue. The initial Tesla grid battery has been followed by additional investments by others in more battery installs in Australia. Those are commercial installations. Is that correct?

The other thing that I didn't mention in my response to the earlier post by SunEagle was that the California Independent System Operator has authorized the payment to behind the meter batteries to put load on the grid. This is unique to California because public policy prefers not to curtail solar generation. There is already negative pricing in the wholesale markets a certain time because of the large buildout of solar generation. What that means is that the ROI of batteries in California is improved by this policy change in the retail markets.

[Bala]

I suspected that was probably not true. The important issue was that the Australian grid was stressed and batteries came to the rescue. The initial Tesla grid battery has been followed by additional investments by others in more battery installs in Australia. Those are commercial installations. Is that correct?

I think South Australia is trying to be the renewable energy state. I dont know all the details and I dont really care, I am a long way from there.

I just wanted to point out that the coal powered stations din not fail in the heat.

Whether or not wind, solar and batteries will be cost effective, maintain reliable supply and save the planet will depend what the individual wants to believe.

[tom rickard]

Those who draw some false equivalence between energy required to create a battery and the energy that passes through it (with some energy always lost in the process BTW) are looking at the whole thing incorrectly. Doing so is ignorant, incorrect and misleading, but suit yourself.

Getting back to this statement..

How else am i supposed to look at a battery other than how many kwh i will be able to harvest from the sun over the course of the batteries lifetime?

That is the cornerstone of off grid power.

When you have off-grid power, you can only price your power as you go. ie: if your system cost $30k, the first kwh you use costs you $30k, when you have used 30000 kwh it has cost you $1 / kwh.

It is plainly obvious that the total energy throughput of a battery is the most significant factor in off-grid power cost.

I'd love to hear your reasons for viewing this differently!

[Ampster]

Getting back to this statement..

How else am i supposed to look at a battery other than how many kwh i will be able to harvest from the sun over the course of the batteries lifetime?

That is the cornerstone of off grid power.

When you have off-grid power, you can only price your power as you go. ie: if your system cost $30k, the first kwh you use costs you $30k, when you have used 30000 kwh it has cost you $1 / kwh.

It is plainly obvious that the total energy throughput of a battery is the most significant factor in off-grid power cost.

I'd love to hear your reasons for viewing this differently!

The biggest point of debate seems to be the life cycle cost of the batteries. Most of the experience on this forum is using Lead Acid and they are probably correct that it costs $1.00 per kWhr over the lifetime of Lead Acid batteries. Even though Lithium batteries have been around for 25 years they are still considered "new" technology" and unproven, especially in an off grid environment. I don't have any better advise than the cumulative knowledge that has developed here over the years. My experience is in a motive environment and my belief is that one should be able to extend the life of motive batteries when used less intensively in a stationary setting. That is only a hypothesis and my experience is only at the most 3 years so I cannot be considered an example of getting a long life out of Lithium batteries.

My thoughts don't answer your fundamental question about the cornerstone of off grid power. However the technological improvements being demonstrated in the grid tie use of Lithium batteries may shed some light on the issue of how one might view this differently. If you believe that Lithium batteries are more efficient and that with proper management they can be discharged deeper and last longer than Lead Acid batteries then you have opened the door to a different way of viewing this issue. That is the bet that a lot of grid battery suppliers have placed and I tend to value their judgement.

I tend to look at large macro economic trends also and there are some interesting trends that may shed light on your question. I admit I am biased. I spent too many years on a sailboat nursing lead acid batteries and taking hydrometer readings. I also read with some alarm about the occasional explosions caused by hydrogen gas. I see Lithium as the preferred chemistry, at least for the big players in the grid support arena. I realize that may have drifted away from your fundamental question.

[tom rickard]

What you do not know is batteries cost money and have a negative EROI. Basically that means they will never give you more energy than was put into them to make them.

There is no way to win with off-grid solar. The law of physics will not allow it. To bad schools today do not teach math and science anymore.

This statement is straight out of the 90's

Where i live, electricity costs around 45c/kwh.

My off grid system is 6 years old and the electricity outputted has currently cost me 76c/kwh.

There are thousands of batteries just like the ones i use that have been cycled far more aggressively and are a few years older.

I'm confident my system will prove to provide less expensive electricity than my power supplier over it's lifetime.

Interestingly, the voices echoing what Sunking is parroting were a lot louder 5 years ago. In another 2 years they will be completely silenced.

It's just too bad the schools of today don't teach manners, and the difference between physics and economics.

[SunEagle]

This statement is straight out of the 90's

Where i live, electricity costs around 45c/kwh.

My off grid system is 6 years old and the electricity outputted has currently cost me 76c/kwh.

There are thousands of batteries just like the ones i use that have been cycled far more aggressively and are a few years older.

I'm confident my system will prove to provide less expensive electricity than my power supplier over it's lifetime.

Interestingly, the voices echoing what Sunking is parroting were a lot louder 5 years ago. In another 2 years they will be completely silenced.

It's just too bad the schools of today don't teach manners, and the difference between physics and economics.

While Li batteries are coming down in price they are still way to expensive for most of the US consumers. But if you choose to live where electricity costs more than 40c/kWh I would say you have a bigger issue to work on. Maybe you need to push your state to require cheaper electricity from the POCO's instead of trying to convince the rest of the county that batteries and solar are the solution to high power costs or that going off grid will convince the POCO to lower their prices.

Try to look at it from the perspective of most of the US. They would not stand for high electric rates and would work with their state governments to make sure batteries are not the answer to the problem.

[Ampster]

Try to look at it from the perspective of most of the US. They would not stand for high electric rates and would work with their state governments to make sure batteries are not the answer to the problem.

Speaking as one voice in California I have busted my pick talking to legislators about high power prices. I am now spending my time, labor and money reducing my cost of energy purchased from the grid. A few years ago in a different home my net cost per kWhr was $0.03. I used a combination of load shifting, solar power and a hybrid inverter with batteries.
I am still using the same batteries in another home where I hope to do the same and get enough life out of them to bring the total cost of energy purchased and generated significantly below $0.20 per kWhr and get bragging rights to being Net Zero. In the meantime I have had two power outages so the backup has had additional value. I also value the quality of life I have where I live in Northern California.

[SunEagle]

Speaking as one voice in California I have busted my pick talking to legislators about high power prices. I am now spending my time, labor and money reducing my cost of energy purchased from the grid. A few years ago in a different home my net cost per kWhr was $0.03. I used a combination of load shifting, solar power and a hybrid inverter with batteries.
I am still using the same batteries in another home where I hope to do the same and get enough life out of them to bring the total cost of energy purchased and generated significantly below $0.20 per kWhr and get bragging rights to being Net Zero. In the meantime I have had two power outages so the backup has had additional value. I also value the quality of life I have where I live in Northern California.

Good for you. Enjoy your life but please stop telling the rest of the US that unless we install solar and batteries we are being bad people for creating carbon.

[Ampster]

Good for you. Enjoy your life but please stop telling the rest of the US that unless we install solar and batteries we are being bad people for creating carbon.

Bad people?. When did I say that?

[J.P.M.]

Bad people?. When did I say that?

If that's a general question for readers, I'll take a shot.

Look up the word "allusion". The no balls way to imply something in a way calculated to be able to more easily deny having said (wrote) it. Perception is everything.

[tom rickard]

So in summary:

The original poster asked how to maximise the life of his batteries.

He was berated by a few others as being stupid, and a time waster for daring to ask that question.

A few statements were made that it was physically impossible for a battery to return more energy than was used in its creation.

This was refuted and backed up by anecdotal evidence as well as reference to scientific study.

When shown to be wrong, the perpetrators of the incorrect statements attempt to deflect by changing subject or playing victim.

Conclusion:
You can get cheaper power from battery/solar than from grid-connect, but for some unknown reason a few people will not like it..

[Ampster]

About a dozen people participated in this thread and it had almost 500 views. Does anyone know what the views are of those lurkers?

[Bala]

Imo to simply compare price per kWh between what poco supply and what some off grinders ca get by on is not a true comparison.

if you price an off grid system that will supply minimum15kw continuously, professionally installed and maintained and factor in replacement costs of items once they are out of warranty then you will have a real price per kWh for the average person to compare.

yes some officers who are happy will a few kWh a day may do ok but not the general population.

I'm off grid, 12 years on first set of batteries, but they are on there way out, need to start gender to weld etc etc. Inverter failed costing $700aud to repair plus 2 weeks on generators. Generator battery fails at an incovenient time. Stress over lack of power when it's raining and have visitors

give me the grid any day, life has more to it than the cost of electricity.

[tom rickard]

Bala. Thankyou for perfectly illustrating my point. 12 years ago the options for off-grid were poor, and the systems weren't as capable as they are now. Times have changed.

Assuming all components will fail at the end of their warranty period, it will still be cheaper for me to have off-grid power than connect to grid. This is an example of a professionally installed system capable of delivering 20kwh daily.

System components:
SMA Sunny Island 8.0
SMA SunnyBoy SB 5.0
BYD BBox (8 units) 20kwh
5kw panels
Auto Start genset (your choice, approx $5k)

Fully installed for $30k, warranty on all components except genset is 10 years, all components are changeover under warranty.

In Australia there have been thousands of this type of system installed, the technology has been verified over the last decade..

[SunEagle]

So in summary:

The original poster asked how to maximise the life of his batteries.

He was berated by a few others as being stupid, and a time waster for daring to ask that question.

A few statements were made that it was physically impossible for a battery to return more energy than was used in its creation.

This was refuted and backed up by anecdotal evidence as well as reference to scientific study.

When shown to be wrong, the perpetrators of the incorrect statements attempt to deflect by changing subject or playing victim.

Conclusion:
You can get cheaper power from battery/solar than from grid-connect, but for some unknown reason a few people will not like it..

Tom. It still depends on what you would be paying for electricity from your POCO. You may be getting cheaper power from you battery/solar system but I seriously doubt the majority of people in the US or elsewhere can make the same claim.

All I ask is that you temper your statement by at least stating where you live and what your POCO charges for a kWh.