let's talk about battery banks- I reckon the "they aren't worth it" thing is wrong

[PVfarmer]

And in this case your explanation doesn't show the credits received for selling the power to the POCO,

The answer whether your consumption is all during daylight or all at night is still the same - $30.

No.
Again- the credits for "selling" are credit = 1 kWh, no $ sign involved.
300kWh a month, all daytime @ 10 cents LCOE/PV = $30 (You used all 300kWh while the PV was outputting energy- not really too likely, but ok)
150 day/150 night also = $30

300kW a month all consumed at night means you put in 300kWh during the day and got 300kWh credit.
You used that credit at a rate of 21 cents. That's $63.
You'd need extra PV to get extra credit because of the fact that you are charged 21 cents when the meter is running against you. That would bump up your payback period.

Now, if instead you'd put all 300kWH into a BESS that cost 10 cents/kWH, so PV+BESS cost 20 cents (not the 21 to POCO), you are getting somewhere.

 

[TommyO]

300kW a month all consumed at night means you put in 300kWh during the day and got 300kWh credit.

Yes.

You used that credit at a rate of 21 cents. That's $63.

You used the credit. When you're using that credit your bill is $0.
Either you can view it as kwh that are worth $0 both buying and selling. (almost what you're doing)
Or you can view it in terms of dollars where the buy and sell rates per kwh are the same. (How I've calculated it in previous post)
Either approach has the buying/selling cancel out, which is what happens with net metering.

If I put in 10 kwh each day for 30 days, then the last few nights before the meter is read I pull out all 300kwh, the meter reads exactly the same as it did the previous month.
With the meter reading exactly the same, the POCO bill is $0.

Now, if instead you'd put all 300kWH into a BESS that cost 10 cents/kWH, so PV+BESS cost 20 cents (not the 21 to POCO), you are getting somewhere.

Yep - you're getting poorer than you would if you didn't buy a battery system.

 

[PVfarmer]

Add $6000 cost for batteries to the non-NM one and compare the results for doing with/without batteries.

YOU can try it!
Note: I was doing this already- this brand new one, WITH typing in the walkthrough, took 20 minutes tops.

Download this, you'll have your own numbers in 30 minutes.
https://sam.nrel.gov/

I'll walk you through one.

Install it, run it, click new project, PV detailed //residential distributed.

Pick your location.

Pick a panel- i went with the 1st 250w Trina on the list

Pick inverter- i typed SMA, 5000TL-US 240v

System design- 12 to a string // 4 strings // 2 inverters // 30 degree tilt

Shading + Snow - up to you- you can upload a shade profile, or skip it for now and fiddle with it later

Losses- add some that you have, or just increase the "givens" a tad- you can fiddle later here too

Lifetime- look up the degradation rate of the Trina panel, or just go with .5 and fiddle later.

Battery Bank- put 6kWh // 48V // AGM (yes to defaults) - again, you can fiddle/adjust later

System costs- all up to you, doesn't have to be 100% perfect adjust it later- here I just changed the overhead/margin to 40 cents/kWh for speed's sake, that knocked it down to $3.07/w installed. (cost = $600/kWh for batteries I think)

Financial parameters- your deal again. This is the most confusing part (for me). Get a basic overall estimate, THEN mess with financials. I left all the default for this case.

Incentives- you can skip at first- defaults seem ok.

Electricity Rates- put in your zip code, download your POCO info, pick your rate, hit ok... then I unchecked net metering and entered .21 buy / .29 sell, and 1% a year for POCO rate escalation (3% seems high-ish, default is zero)

Load Profile- take your yearly bill kWh total and adjust the "1" so the total is close enough to yours. I changed the 1 to 1.5 for 9,029kWh a year.

Hit "Simulate" down in the left corner...
DONE!!

I right clicked the "summary table" and copied it here.
TRY IT!
:happyyes:

Metric Value
Annual energy 16,475 kWh
Capacity factor 15.7%
First year kWhAC/kWDC 1,374 kWh/kW
Performance ratio 0.81
Battery efficiency 82.53%
Levelized COE (nominal) 9.71 ¢/kWh
Levelized COE (real) 7.68 ¢/kWh
Electricity cost without system $3,430
Electricity cost with system $-1,348
Net savings with system $4,778
Net present value $49,144
Payback period 4.6 years
Net capital cost $36,818
Equity $0
Debt $36,818

Bump the BESS up to $800/kWh...barely changes things...

Metric Value
Annual energy 16,475 kWh
Capacity factor 15.7%
First year kWhAC/kWDC 1,374 kWh/kW
Performance ratio 0.81
Battery efficiency 82.53%
Levelized COE (nominal) 10.00 ¢/kWh
Levelized COE (real) 7.91 ¢/kWh
Electricity cost without system $3,430
Electricity cost with system $-1,348
Net savings with system $4,778
Net present value $48,653
Payback period 4.8 years
Net capital cost $38,201
Equity $0
Debt $38,201

I did this, BESS=$1200, and the BESS = $800 by going BACK to the system costs page, changing them, and hitting simulate again.
TRY IT!!

Metric Value
Annual energy 16,475 kWh
Capacity factor 15.7%
First year kWhAC/kWDC 1,374 kWh/kW
Performance ratio 0.81
Battery efficiency 82.53%
Levelized COE (nominal) 10.59 ¢/kWh
Levelized COE (real) 8.38 ¢/kWh
Electricity cost without system $3,430
Electricity cost with system $-1,348
Net savings with system $4,778
Net present value $47,671
Payback period 5.2 years
Net capital cost $40,967
Equity $0
Debt $40,967

Last one - BESS = $3000/kWH
Metric Value
Annual energy 16,475 kWh
Capacity factor 15.7%
First year kWhAC/kWDC 1,374 kWh/kW
Performance ratio 0.81
Battery efficiency 82.53%
Levelized COE (nominal) 13.24 ¢/kWh
Levelized COE (real) 10.47 ¢/kWh
Electricity cost without system $3,430
Electricity cost with system $-1,348
Net savings with system $4,778
Net present value $43,254
Payback period 6.9 years
Net capital cost $53,414
Equity $0
Debt $53,414

 

[ADub]

Get a room you two. Good lord


Sent from my iPad using Tapatalk

 

[PVfarmer]

Get a room you two. Good lord

BEST COMMENT YET!
And only seven little words!
Do you know of a room with an accountant in it??

 

[PVfarmer]

You used the credit. When you're using that credit your bill is $0.
Either you can view it as kwh that are worth $0 both buying and selling. (almost what you're doing)
Or you can view it in terms of dollars where the buy and sell rates per kwh are the same. (How I've calculated it in previous post)
Either approach has the buying/selling cancel out, which is what happens with net metering.

If I put in 10 kwh each day for 30 days, then the last few nights before the meter is read I pull out all 300kwh, the meter reads exactly the same as it did the previous month.
With the meter reading exactly the same, the POCO bill is $0.

Originally Posted by PVfarmer
300kW a month all consumed at night means you put in 300kWh during the day and got 300kWh credit.

Yes.

You used that credit at a rate of 21 cents. That's $63.


You used the credit. When you're using that credit your bill is $0.


Scenario B - net metering, producing and consuming 300kwh/month
$.10/kwh * 300kwh = $30

The fact that your bill is $0 is irrelevant - why don't you tell me why you're talking about bill instead of cost all of a sudden? Bill = zero means energy was free?? OF COURSE NOT!!

I think I forgot to type the rest of this.

300kW a month all consumed at night means you put in 300kWh during the day and got 300kWh credit.
You used that credit at a rate of 21 cents. That's $63.

You USED $63 at night- no PV, no BESS, they use the number of kWh (all of them, 300) to compute your bill.
That $63 cost you, personally, $30 to produce.
Your cost went from $30 to $33 there - they charged you $3 to get your $30 back out. Because, again, at 300kWh *all* at night, that's 300kWh at 21 cents printed into that row of the bill. (not the POCO bill- the COST)
Get it?

Your cost is $3 higher (or 10%, nothing to sneeze at) than your Scenario B.
So yes, *when* the power is used most certainly is factor! And NO, net metering isn't simple or always the best idea!

In fact, seems like you'd want to get some BESS action if the price was right and you used more than 50% of your energy at night- which most homes do!
Hmm...

 

[TommyO]

The fact that your bill is $0 is irrelevant - why don't you tell me why you're talking about bill instead of cost all of a sudden? Bill = zero means energy was free?? OF COURSE NOT!!

No - but it DOES mean that NONE of your cost is paying the POCO.
And therefore ALL of your cost is the cost to generate which is $30 (300kwh*.10/kwh)

You USED $63 at night- no PV, no BESS, they use the number of kWh (all of them, 300) to compute your bill.
That $63 cost you, personally, $30 to produce.
Your cost went from $30 to $33 there - they charged you $3 to get your $30 back out.

They didn't charge me $3.
The bill was $0.
It cost me $30 to produce it, and putting it into and out of the grid cost me $0.

Your cost is $3 higher (or 10%, nothing to sneeze at) than your Scenario B.

No, it's still the same $30 - I haven't paid anything additional to the POCO. All I've had to pay for is the PV.

So yes, *when* the power is used most certainly is factor! And NO, net metering isn't simple or always the best idea!

Net metering is fairly simple... Most people understand it. Obviously you don't even after at least 3 people have tried to explain it to you.
It certainly isn't always the best idea. Nobody here has said it is.
However net metering beats batteries in all 3 states we've reviewed and probably will in the others with net metering too.

I give up - I have tried to be patient and explain it to you, but you are stuck in your beliefs and won't examine them even when the math shows them to be wrong.

 

[PVfarmer]

The bill was $0.

Sure, and every day of the year was exactly the same?

Simple question:
Given the 3 variables of weather/PV output, electricity usage, and seasonal day length, how many days out of 365 will "the bill be zero"?

My best guess is a few. Seeing as the system never changes and all 3 of those do.
My second guess would be: none!

Does that help? You have to get the right equation before you do the math.

NONE of your cost is paying the POCO...if the kWh for that month or year happen to be exactly zero. You might owe a little bit, or lose some credit. Or owe a lot, or lose a lot of credit...

 

[wwhitney]

Hi PVfarmer,

Long time, eh? I've been on vacation. But I found this SAM tool intriguing, so I played around with it a little. My comments:

First of all, it has a lot of bells and whistles. I suggest turning off all the financial bells and whistles and just doing a simple straight line analysis to start. Once you understand that, you can turn on some of the bells and whistles to see what impact they have. To do this simplest analysis:

On the Lifetime tab, set the Degradation rate to 0

On the Financial Parameters, set a bunch of things to 0: Debt Fraction, inflation rate, real discount rate, and all the tax rates.

On the Electricity Rates, set the escalation rate to 0

On the Incentives page, set the Federal and State tax credit to 0%.

Now with those options when you hit Simulate and go to the Cash Flow tab, you should see that all the columns for years 1 through 25 are exactly the same. That's what I mean by straight line analysis. This is the simplest, easiest to understand way to model the purchasing decision. Obviously the bells and whistles if used correctly will give you more accurate answers, but let's start simple.

When you do hit Simulate and get a Summary, the key line item for economic purposes is the Net Present Value (NPV). For the simple straight line analysis, that's just the your electricity bill savings/refund over the lifetime less the equipment costs. It's the amount of money you make by installing the system instead of doing nothing. If you want to compare two different system, economically the one with the higher NPV makes you more money.

YOU can try it!
Electricity Rates- put in your zip code, download your POCO info, pick your rate, hit ok... then I unchecked net metering and entered .21 buy / .29 sell,

Load Profile- take your yearly bill kWh total and adjust the "1" so the total is close enough to yours. I changed the 1 to 1.5 for 9,029kWh a year.

OK, I tried your example, and the above are the critical choices, along with the total energy generation per year for the PV info you provide. For my location the system you suggested was generating about twice as much as the annual usage of 9,029 kWh/year. That's fine, you are interested in the case where a resident is a net annual generator of energy and can get reimbursed well for that. I think that may be a very special case in the US, but I haven't really looked into that.

First, a simple observation: everyone here will tell you that a battery system makes no economic sense with the above utility rates. You'd be much better off selling your excess energy at $0.29/kWh than saving it for later to displace $0.21/kWh in nighttime usage costs, even if batteries were free. In fact, SAM will tell you as much, if you know how to use it. Do this:

Enter any PV system you like with the above electricity rates and the settings for the straight line analysis and with no battery system. Do the simulate and get the NPV. Now add a battery system and repeat the simulation to get a new NPV. The NPV with the batteries will be lower, you make less money by adding batteries that you would without them. Basically the batteries can never pay themselves off. They can't--the optimal economic strategy with the above electricity rates is not to use the batteries at all.

Cheers, Wayne

 

[PVfarmer]

When you do hit Simulate and get a Summary, the key line item for economic purposes is the Net Present Value (NPV).

Howdy Wayne-
Thanks a million! I've got to digest all that- the NPV was really messing me up. Is there a way to explain how NPV relates to ROI (if it does) in a sentence or two?
Don't forget - our taxes paid for SAM!!
Pretty cool.

I get what you're saying about selling it all at the high rate of 29 and buying back at 21- except that isn't it-- if the BESS was "free", ie cost nothing, you would be losing 8 cents by not selling it at 29, and paying that 8 cents plus X cents/kWh (to yourself!) for storage, so if X cents LCOS <= 13 cents <--(21-8=13), you'd be...ok?

You'd be losing 8 cents, but avoiding the 21 cent cost IF the above < 13 was the case?

Equal to 13 cents would be...not an improvement financially, BUT you'd have backup power, maybe.

I'm going to investigate that straight line thing now- that's a real pro tip, thanks! :happyyes:

 

[wwhitney]

I get what you're saying about selling it all at the high rate of 29 and buying back at 21- except that isn't it-- if the BESS was "free", ie cost nothing, you would be losing 8 cents by not selling it at 29, and paying that 8 cents plus X cents/kWh (to yourself!) for storage, so if X cents LCOS <= 13 cents <--(21-8=13), you'd be...ok?

Your accounting is all off. Let me fix your sentence for you:

I get what you're saying about selling it all at the high rate of 29 and buying back at 21- - if the BESS was "free", ie cost nothing, you would be losing 29 cents by not selling it at 29 cents, and paying 0 cents for storage, and you'd avoid 21 cents in costs when you take it out of the battery, so if 29 + 0 < 21 you'd be OK. But 29 is not less than 21, you always lose 8 cents, even if the battery is free.

In fact, with the rate structure we are discussing now, the proper economic use of a battery system is to shift your usage the other way, from day to night. That way all of the PV energy you are generating you get to sell at 29 cents, and for all of your usage you are paying "only" 21 cents.

In case that isn't clear, consider this simple question about this rate structure with PV only and no net metering. If you are a net generator during the day and selling extra power at 29 cents/kWh, and you charge your electric car an extra 1kWh during the day, how much did that 1kWh cost you? The answer is 29 cents, your refund from the POCO went down by that amount. If you charge your car at night, when the PV isn't producing at all and you are a net consumer of energy, how much does that kWh cost you? The answer is 21 cents, the POCO sell rate.

Howdy Wayne-
Thanks a million! I've got to digest all that- the NPV was really messing me up. Is there a way to explain how NPV relates to ROI (if it does) in a sentence or two?

For the straight line analysis, and buying the system up front with no loan, the ROI for your system purchase will be the percentage you need to set in the "Real Discount Rate" field (or the "Inflation" field, when only one is non-zero they work the same) to make the NPV come out to 0.

Cheers,
Wayne

 

[Electric-Light]

Lets talk about demand and burning fossil fuel

Lets talk about demand and burning fossil fuel

Batteries and capacitors enable you to stretch out kWh over a long term or compress it into a short term, such as charging at a rate where generators can operate efficiently or charge slowly from a low rate source to power high demand.

The battery in an iPhone 6 has a capacity of about 6 Wh.

When you turn the key on your car, the starter draws about 200A for about four seconds. After voltage drop, voltage delivered at the starter terminals is around 8v or input power of 1.6kW. So, the starter consumes 6,400watt-seconds or 1.78Wh. Photovoltaic industry math is blind to demand consideration. Simple solar math says iPhone 6 battery will start a car three times. The value of car battery is in its ability to deliver 1.78Wh in *four seconds*. A battery that delivers 6Wh over one day is completely useless.

Let's talk about DEMAND here, which is extremely valuable, but usually ignored by solar advocates. It's a resource that is sometimes more valuable than kWh. Some utilities have residential rate plans with demand. http://www.aelp.com/Rates/ourrates.htm

Meter fee + high kWh rate residential plan contributes to fixed when all the power is purchased, but it lets solar owners mooch on the demand capacity from the grid. The current solar mindset is that if they have a 2kW solar system that trickle charge the grid, 300kWh of accumulation offsets 75kW load they use 4 hours a month. Freeloading factor by solar users is higher when generation and demand peak don't match. A demand charge of say $12/kW and a lower kWh rate creates a way for the average people to be able to save on power bills while making it difficult for solar owners to freeload the demand capacity.

Demand charge means it pays to be conscious about load level, for example, running dryer and oven back to back is not the same as running them at the same time. kWh based "annual net metering" BS means power generated during winter can deduct kWh used by sauna, pool and such luxury at some rich people's house. A demand charge ensures such usage is billed accordingly. A 240v 200A service allows 48kW or 38kW continuous, but only a luxury lifestyle will need that kind of demand. $12/kW demand charge means 25kW demand to support luxury lifestyle at home will get billed $300/mo + kWh usage.

Solar panels don't make economic sense when you can't count the low value they produce during the winter at retail price.

Normal residential bill doesn't charge separately for demand, but the kWh rate is inclusive of it. Solar owners are essentially free loading on demand capacity as well night time availability. You'd need a 25kW inverter plus a large battery system to support demand. Off grid solar homes have a very limited demand capacity.

Throwing photovoltaic panels out, I would like a smoke stack please!
Co-generation is where it is at.

http://cumminsengines.com/dual-fuel

Diesel engine can not ignite straight natural gas, but you can load it with natural gas and seed the ignition with diesel fuel. The fuel consumption efficiency of generators are terrible at light load. At about 3/4 load, you can get pretty good generation efficiency and run a very high proportion of natural gas.

A practical use of batteries is to stabilize and buffer generator load to maximize fuel cost efficiency, so you can run maximum proportion of natural gas. You start charging battery to keep the generator loaded to economically efficient point. (running on highest percentage of natural gas). The heat from engine can provide hot water and space heating, or cooling using absorption cycle.

Batteries have a high charging rate until about 80% and it slows down. When the electrical load level is higher, you start blending in battery power to your load, so that once load level drops, batteries can start absorbing charge to keep the generator loaded to high efficiency region.
At the highest facility demand, the generator can supply power together with the battery to minimize demand during super peak and the battery charging could be timed during low demand so that generator does not slip into the high diesel consumption region.

Batteries are very costly per kWh storage and they are bulky but they're very good at providing very small loads for a long period of time efficiently, and I believe LiFePO4 types are pretty good at providing relatively heavy load quite efficiently.

Generators have a very high idle consumption so they're not practical for powering tiny loads for a long time. Solar panels are completely uncontrollable and absurdly expensive per kW output, but they do great in powering tiny loads and slowly charging batteries. For example, remote location that needs continuous power in the order several watts to several tens of watts. Scientific instruments, and rail road signals for example.

 

[ggunn]

Oh, wow. This oughta be good.

 

[mivey]

Oh, wow. This oughta be good.

I'm sure. But he does make some excellent points about demand and the problem with energy-only rates.

The energy-only rates are based on an assumption about load shape and trying to estimate the demand so some of those costs can be recovered in the energy charges. One reason they were designed that way was to cut down on the cost of metering and billing in order to save the customers money. Loads used to be reasonably predictable for certain traditional rate groups and you could make a reasonable estimate of the demand based on the energy usage.

Monkey around with the load shape and the standard energy-only rate is no longer applicable and does not recover costs appropriately. Distributed generation, abnormally high peak demand loads like some electric instant water heaters, fast charging electric vehicles, retail business loads at home, etc. are prime examples of ways to monkey around with the traditional load shape.

Just because you can push your costs off on your neighbor doesn't mean you should, or that you should be allowed to do so.

 

[PVfarmer]

solar owners mooch on the demand capacity from the grid. A demand charge of say $12/kW and a lower kWh rate creates a way for the average people to be able to save on power bills while making it difficult for solar owners to freeload the demand capacity.

kWh used by sauna, pool and such luxury at some rich people's house. A demand charge ensures such usage is billed accordingly. A 240v 200A service allows 48kW or 38kW continuous, but only a luxury lifestyle will need that kind of demand. $12/kW demand charge means 25kW demand to support luxury lifestyle at home will get billed $300/mo + kWh usage.

Normal residential bill doesn't charge separately for demand, but the kWh rate is inclusive of it. Solar owners are essentially free loading on demand capacity as well night time availability. You'd need a 25kW inverter plus a large battery system to support demand. Off grid solar homes have a very limited demand capacity.

At the highest facility demand, the generator can supply power together with the battery to minimize demand

Solar panels don't make economic sense when you can't count the low value they produce during the winter at retail price.

Generators have a very high idle consumption so they're not practical for powering tiny loads for a long time. Solar panels are completely uncontrollable and absurdly expensive per kW output.

You raise quite a few issues.

The first 3 parts are about how demand charges are supposed to punish rich people, and then you are running your own generator to avoid....demand charges (just like people with solar are...).

I wouldn't pay retail price for solar panels if I was in Alaska either, so that makes sense.

Uncontrollable is a very creative description of solar panels, would you like to expand on that one?

And if a cost of under a dime (perfectly realistic) per kWh of output for solar is "absurd", then...that's weird, it looks like you currently may be paying more than that to your own grid.

 

[PVfarmer]

I'm sure. But he does make some excellent points about demand and the problem with energy-only rates.

The energy-only rates are based on an assumption about load shape and trying to estimate the demand so some of those costs can be recovered in the energy charges. One reason they were designed that way was to cut down on the cost of metering and billing in order to save the customers money. Loads used to be reasonably predictable for certain traditional rate groups and you could make a reasonable estimate of the demand based on the energy usage.

Monkey around with the load shape and the standard energy-only rate is no longer applicable and does not recover costs appropriately. Distributed generation, abnormally high peak demand loads like some electric instant water heaters, fast charging electric vehicles, retail business loads at home, etc. are prime examples of ways to monkey around with the traditional load shape.

Just because you can push your costs off on your neighbor doesn't mean you should, or that you should be allowed to do so.

You didn't explain how monkeying with the load shape = pushing costs on your neighbor.

Distributed generation lessens demand on the grid-> less demand = less repair and/or upgrades, that leads to lower bills.

The Northeast’s Electricity Bills Have Dropped $460 Million Since They Started Paying For Carbon

http://thinkprogress.org/climate/2015/07/14/3680269/rggi-boosts-economy-lowers-carbon/
. The decrease in electricity demand actually reduces the overall price of electricity. That means the costs go down for everyone, not just someone who installed new, efficient windows. So while opponents of the Clean Power Plan say that it will raise electricity prices for consumers and depress the economy, putting a price on carbon can actually have the opposite effect.

 

[mivey]

Photovoltaic industry math is blind to demand consideration.

And if a cost of under a dime (perfectly realistic) per kWh of output for solar is "absurd", then...that's weird, it looks like you currently may be paying more than that to your own grid.

Case in point.

Simple solar math says iPhone 6 battery will start a car three times. The value of car battery is in its ability to deliver 1.78Wh in *four seconds*. A battery that delivers 6Wh over one day is completely useless.

Funny how PVfarmer glossed over that one isn't it?

The first 3 parts are about how demand charges are supposed to punish rich people, and then you are running your own generator to avoid....demand charges (just like people with solar are...).

Not quite "just like". The generator mention can run when needed, i.e. has more control. Solar runs when there is, well...solar.

 

[mivey]

You didn't explain how monkeying with the load shape = pushing costs on your neighbor.

Read Electric-Light's post. If you really don't understand, either he or I can see if it can be explained better but it should be clear from his example.

Perhaps this might help: less water delivered in the same pipe = bigger pipe / gallon. That means the kWh charges no longer cover the pipe & pump cost. You can't have a smaller pipe because there are still times when you still need the old gal/minute flow (i.e. when the sun is not cooperating, when the panels are out for repair, etc.).

Kind of like you wanting to have a personal well to use sometimes but also want the city water supplier to keep the connection and supply on standby in case you need them. If you do that, then they can't roll the pipe and pump capacity costs into the per gallon charges because the gallon/diameter and gallon/psi ratio has changed.

Distributed generation lessens demand on the grid-> less demand = less repair and/or upgrades, that leads to lower bills.

There are reliability and availability issues that keep some DG from being a direct replacement for grid resources.

 

[ggunn]

The first 3 parts are about how demand charges are supposed to punish rich people, and then you are running your own generator to avoid....demand charges (just like people with solar are...).

Solar cannot be dependably used to avoid demand charges. One cannot be sure that a PV system will be running at high output during every 15 minute period of high demand, and it only takes one to incur the charge.

 

[PVfarmer]

Read Electric-Light's post. If you really don't understand, either he or I can see if it can be explained better but it should be clear from his example.

Perhaps this might help: less water delivered in the same pipe = bigger pipe / gallon. That means the kWh charges no longer cover the pipe & pump cost. You can't have a smaller pipe because there are still times when you still need the old gal/minute flow (i.e. when the sun is not cooperating, when the panels are out for repair, etc.).

Kind of like you wanting to have a personal well to use sometimes but also want the city water supplier to keep the connection and supply on standby in case you need them. If you do that, then they can't roll the pipe and pump capacity costs into the per gallon charges because the gallon/diameter and gallon/psi ratio has changed.

There are reliability and availability issues that keep some DG from being a direct replacement for grid resources.

Originally Posted by Electric-Light
Photovoltaic industry math is blind to demand consideration.

Originally Posted by PVfarmer
And if a cost of under a dime (perfectly realistic) per kWh of output for solar is "absurd", then...that's weird, it looks like you currently may be paying more than that to your own grid.
Case in point.

Originally Posted by Electric-Light
Simple solar math says iPhone 6 battery will start a car three times. The value of car battery is in its ability to deliver 1.78Wh in *four seconds*. A battery that delivers 6Wh over one day is completely useless.
Funny how PVfarmer glossed over that one isn't it?

Not quite "just like". The generator mention can run when needed, i.e. has more control. Solar runs when there is, well...solar.

There are reliability and availability issues with some grids that make DG part of the solution. This is a fact- it just happened here, the POCO avoided spending millions on a new substation by pushing an energy efficiency program (refunds on better AC units/water heaters, etc) AND, at the same time, DG.

I'm not saying there aren't "political issues" re: DG, but I don't really think it's rich vs. poor people or renewables vs. fossils.
Btw, solar panels have no moving parts- have you ever seen a solar panel repair shop?

less water delivered in the same pipe = bigger pipe / gallon
You must mean "more empty pipe per gallon"?

You can't have a smaller pipe
I've never heard of a POCO installing smaller feeders.
Frankly, I wasn't going to say it, but this whole "the grid is a free battery" thing sounds like the "mooching off the grid" to me.
That is, like you are saying, not contributing any payments towards "upkeep" of the grid, while having it for backup whenever you want.
When someone is putting out MORE energy than they use, it is going into a neighbor's house and taking strain off of the grid, which can keep energy rates the same, or even lower them for everyone else.

They had to fix that "too much DG" problem already in Hawaii.
Pretty neat really- the microinverters help HECO figure which lines are the "weakest link"

Right off the bat, Enphase was able to prove its microinverters were accurate as sensors, by showing that they had recorded past voltage spikes that correlated to HECO’s system-wide voltage readings. “That gave them confidence that the data is accurate,” he said. Interestingly enough, Enphase's data indicated that voltage fluctuations on the circuits showed little correlation to how much solar PV was installed on each circuit.
The primary issue for solar-heavy circuits, instead, had to do with the age and quality of the power-conducting cables and transformers on each circuit, he noted. “A 50-year-old network can act very different than a brand-new network,” he said, with older equipment showing more propensity for problems caused by out-of-range voltages.

http://www.greentechmedia.com/artic...g-enphase-data-to-open-its-grid-to-more-solar

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If you are paying 20 cents for kWhs and you can get your kWhs for 10 cents from solar panels, to do so would be absurd?
If you want to think that, it is your business. You are making a mistake there however.

Glossed over?
A 6 watt hour battery sure is useless for running a house- what about the right size? 6kW? 12kW? k?

Generators only run when there is fuel, which costs money, and cost a LOT more in Alaska, so....?

Let's see...Stirling engines....all you need is heat and cold...you're in Alaska, it's 20 below outside and your woodstove is cranking away....sounds like free electricity to me, no sun involved...
Quieter than internal combustion also!
Then in the summer, you've got sun + permafrost... :happyyes:

http://motherboard.vice.com/blog/ditching-the-grid-with-a-woodstove-and-a-100-stirling-engine-q-a

https://en.wikipedia.org/wiki/Stirling_engine