Mikey - Magic Shade Tree Question

[atmdad]

When your system is generating more power than you are using I am assuming you are "selling power" back to SDG&E. What is the average cost per KWH that SDG&E is paying/crediting you?

[Mikey]

That's a good question.

The really short answer is...it's complicated.


The next shortest answer is...

It depends on the time of day and on the calendar month, and on which rate option you've chosen with the utility. Basically I get credited at the same rate I would be paying if I were to be using the kWh instead of feeding it back.

I'm on the TOU-EV-5 rate (for EV owners), which works particularly to may advantage.

SUMMER
$0.50/kWh on-peak
$.029/kWh off-peak
$0.09/kWh super off-peak

WINTER
$0.26kWh on-peak
$.025/kWh off-peak
$0.09/kWh super off-peak

It's changed a little since last year when I think it was $0.56/kWh on-peak

With all the stuff I've done to my house in the past couple of years I've become a little OCD about all of this, and track it almost every day. I'll put up some more details later. But I've got it now so I use virtually no net energy (often negative) in the on-peak period and probably at least 90% in the super off-peak.

[Softball Bat]

[Mikey]

Here are a couple of example of how it works. I made these charts using 15 minute data that any SDG&E customer can get from the website.

The first one is from June of last year. Weather was still pretty cool so no AC was running and everything is pretty smooth and regular. Also, I was charging my EV every night (not using it so much right now) so the storage battery and car were charging at the same time. Any time the values are positive, I'm purchasing power from SDG&E and paying the TOU rate. Any time it's negative, my PV system is producing more that I'm using and I'm selling power back to SDG&E at the same rate I'd be paying for it.

At that time, I only had 8 kWh of capacity and was only discharging the battery between 4 pm and 9 pm.

The lower chart is from a week ago. The weather was quite warm and we were using the AC a lot. Also, since June of last year and now, I've added 50% to my PV system and increased my battery to 20 kWh. Notice that even with a larger PV system, I still need sometimes go import power from the grid.

The color codes show the cost per kWh. Green = $0./09/kWh, gray = $0.29/kWh and blue = $0.50/kWh.

Most people think that if you have PV and a battery that you would charge the battery from the PV and use it when the sun isn't shining. But that's not it. The whole advantage is in the "arbitrage" - charge when the prices are low and feed the grid when the prices are high. Notice on the second chart that the battery is set up to cover all of my usage between 4 pm and midnight. Between 4 pm and 5 pm the battery doesn't need to do its thing because the PV system has it covered. There's actually a spike in the AC usage at about 5:30 that the battery couldn't cover but, other wise I'm neither using or exporting between then and midnight. The vast majority of what I take from the grid is between midnight and 6 am when prices are the lowest.

Imagine all those green bars, when the battery is charging, if they were moved over to 5 pm. Then, instead of $0.09/kWh I'd be paying $0,29/kWh or $0.50/kWh. And instead of charging the battery in the middle of the day, I'm getting $0.29/kWh when the PV exports. At this time of year, I'm using slightly more than I produce over the 24 hour period, but still coming out ahead because of the arbitrage.

Since my annual true-up at the end of May, I've actually built up a credit of about $300.00, which carries over from month to month. I'll be working this down in the winter when the PV is producing less but I still have to run the heat pump heater and the heat pump water heater.





There are a lot of moving parts to the analysis but I've put together a spreadsheet that tracks very closely to my SDG&E bills. My goal is to be able to retire without ever having to pay another $$ to SDG&E, and also have enough PV and storage to last through a power outage. During an outage - that's when the PV will need to charge the battery.

[atmdad]

Thanks Mikey, solid breakdown.

I was asking because I was approached by one of those companies that want to put solar on my house at their cost and sell me power at a lower than SDG&E fixed price. Essentially leasing my roof top to them. I took the bait and asked them to tell me more. I politely told them to pound sand after reading the T&C's of the contract. No way in hell I wanted sign up for a 25 year PPA among other terms.

[mvscal]

a 25 year PPA

That is about break even cost.

[Mikey]

Thanks Mikey, solid breakdown.

I was asking because I was approached by one of those companies that want to put solar on my house at their cost and sell me power at a lower than SDG&E fixed price. Essentially leasing my roof top to them. I took the bait and asked them to tell me more. I politely told them to pound sand after reading the T&C's of the contract. No way in hell I wanted sign up for a 25 year PPA among other terms.

Good decision. A lease or a PPA (Power Purchase Agreement) is a viable way to get PV if you really, really want it and can't afford to purchase the system outright. But you know that they're making money off the deal that you would be realizing if you owned it yourself. Plus, like you said, you're saddled with a long term contract, which can also be problematic if you ever want to sell your house.

A better way to go, if you can't pay cash, is to finance with a HELOC. If you have equity in your home and good credit you can probably get one now at under 3%, and PV costs have come way down in the past 5 or 6 years. When we installed our first 5 kW in 2012 (we added another 2.5 kW last year) we paid about half up front and financed the rest. We didn't really have another choice because the lease or PPA options were pretty new and not as available back then but, mostly, we needed a large shade structure for our back patio and found a contractor who could engineer and install both the structure and the panels on top. We were able to roll the entire cost into the 30% tax credit (I think it's 26% or 28% now) because it's technically a "ground mount" PV system. That was a substantial savings on a structure that we needed to build anyway.

[smackaholic]

So, you actually buy cheap electricity, store it, then sell it back when the market is favorable to do so?

You capitalist pig, you!!!!!!

Actually, being a capitalist pig myself, I'd be all for it.....if you weren't asking the rest of us to subsidize this little crony capitalist venture.

But that isn't the case.

This system continues to use substantial government subsidies to fund what could best be described as a Rube Goldberg energy production storage system.

I understand that energy grid management is a tricky thing which requires the ability to store power when supply exceeds demand.

In prehistoric times, you remember them, in the previous century, where you had the energy company running the generators, this worked pretty well. They used reservoirs, typically to store power.

This system worked pretty well. There weren't brownout. Power was cheap. And I don't think there were as many cases of overworked powerlines burning down the state.

Today, we have millions of tiny little generating plants, very expensive tesla powerwalls, made from hard to find stuff, often located in, well, shitholes.

But upper middle income hippies feel better, because they are doing their part....with a little help from fellow taxpayers, to save the planet!!!!!!

I actually do think roof, or even poolside solar makes sense in your neck of the woods. It certainly makes more sense than the 100 acres or so of forest that was recently cleared to build a solar farm next to my bro-in-law's house last year.

But expensive light weight storage in stationary applications makes zero sense for anyone tied to the grid. Large scale gravity storage is far cheaper and better environmentally. But it ain't about being cheap or environmental. It is about Big PV and Big Li Ion.

I find it kind of ironic that someone in Local, would site emergency power as a benefit of having his own storage.

Here in the land of less than perfect weather, we've always had that concern. Power outages from ice storms or hurricanes are the suck.

When was the last time one of those hit SD?

They don't. 30 years ago, power outages were a thing in places with shit weather and 3rd world power grids.

You don't have the former, but the latter is becoming a thing, thanks to your Rube Goldberg system.

Even if stationary Li Ion was economically wise, I would use the same argument used against oil. That argument is yeah, there's enough....for now. But what about in 50 years?

This push to ramp up Li Ion for the short term price benefit, very well may become a problem when it gets rare or when East Bumfukkistan turns off the Li tap.

Seems to me that every last bit of chemical electron captivity done today should be for portable storage (phones, cars, dildos, etc....) rather than ensuring Mikey has free interweb pron during the next upper mexico blackout.

[Mikey]

Mikey, does SDG&E send you one bill a year for usage? My neighbor has had solar for about 2 years and told me the other day that they got a 600 bill for the year in September after only getting 10 or 11 dollar bills monthly. She said that SCE told her it was for the overages for the whole year and asked me if I got those. I've had my panels up for over 10 years now and have never received any bill monthly or yearly from SCE that was over 6 dollars during that time.

I get a bill every month that shows how much I've used and the net charges for the month, which includes a $16 meter charge to be on the EV TOU rate. But it also says not to pay it because my "true-up" is after the May billing cycle. Any charges or credits accumulate for the whole year, and then I pay the balance at the end of May. I usually build up a credit in the spring and early summer when there's plenty of sun and I'm not using any AC. Then I work through the credits in the late summer and winter, when there's not nearly as much PV production and I'm using electric heat.

SCE may do things differently.

Before this year I was paying about $2,000 per year for the true-up. In May of this year I actually carried over a credit because of the clean fuel rebate for my EV. And now I've added more panels and the battery, but also a heat pump heater and water heater. So, we'll see how it works out in May.

And don't worry, 'holic, I'll have an answer for your post at some point. I just need to put together a line-by-line rebuttal to your obvious ignorance. It could take a while because there's so much to work with.

[smackaholic]

Where am I mistaken?

Is there a tax/power company subsidy?

Do we have inexhaustible supplies on lithium?

Is extracting these vast piles of lithium and other components of such systems environmentally friendly?


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[Smackie Chan]

We bought solar panels shortly after we bought our house in 2018, but didn't buy a battery because it wasn't cost effective. Battery woulda cost ~$8K and we'd never get an ROI. Financed the panels, then refi'd the house shortly afterward. Made one or two payments on the panel loan, then rolled the cost of the panels into the mortgage refi, resulting in the mortgage payments being about the same as they were before, which effectively made the panels almost free if you choose to look at it that way, which I do. For about 8-9 months out of the year, we pay no electric bill since we produce more than we use. During the summer months, we pay a little. Got a $10K fed tax credit in '19 and a small AZ tax credit. You'd think that the PHX area would be perfect for solar power, but it's actually too hot to be optimal. Efficiency drops when it gets above ~85º, and this year we had the hottest summer on record by far. But it still seems solar was a good buy for us. Re-fi'd the mortgage again earlier this year to put in the pool, and am currently doing it again to get the VA interest rate reduction; will be paying 2.375%. Mortgage pmt on a 2850 sq. ft. house w/ a pool and solar will be cheaper than what most people pay for rent on a 2-br apt.

[Mikey]

Nice job on the refi, Smackie.

We refinanced earlier this year from 3.875% to 3.25% (should have waited a little longer), plus rolled a $35,000 balance on a HELOC (at 4.00% but adjustable) into the new loan. We reduced our monthly payment by $700 when you include the $500 we were paying on the HELOC. Now a couple of hundred a month less than our daughter is paying on a 1 BR apt downtown.

Thinking about doing the refi again, but it's a pain in the ass and we're pretty happy with what we have.

You're absolutely right about the heat affecting solar panel performance. That's why you need to make sure that there's some air space underneath on a rooftop system. Our patio cover is pretty ideal because it's a lattice underneath and then 10 feet of empty space. If you have the ability to watch or record what your panels are putting out, go out some hot day and hose them down for a few minutes. You can see the effect pretty clearly.

[Mikey]

So, you actually buy cheap electricity, store it, then sell it back when the market is favorable to do so?

You capitalist pig, you!!!!!!

Actually, being a capitalist pig myself, I'd be all for it.....if you weren't asking the rest of us to subsidize this little crony capitalist venture.

But that isn't the case.

This system continues to use substantial government subsidies to fund what could best be described as a Rube Goldberg energy production storage system.

It's no more "Rube Goldberg" than an automobile or a vacuum cleaner. Or an airport security screening system. You just have to have the intelligence to be able to get it.

I understand that energy grid management is a tricky thing which requires the ability to store power when supply exceeds demand.

It's a little more complicated than that. But, again, you have to have a little higher than a third grade grasp of the real world and the ability to understand that there is more than one variables involved.

PV and storage both provide a tangible economic benefit to the grid and, hence, to society. You may actually be on the cusp of having this sink into your pea-sized brain (probably not), but the more local (i.e. on-site) generation there is the less the utilities have to spend on both the size of and distance travelled by the wires, and the amount of generation required. You have to have sufficient generation to satisfy the peak load on the system. if you have a peak load of 100 kW in the afternoon and 10 kW at night, you need to have 100 kW of generation capacity 24/7. If you can move 30 of those 100 kW from daytime to night time, you need 70 kW, etc. More generation and more T&D is hugely expensive. Utilities pay large customers big $$ to decrease their load during high peak events (this is called "demand response"). This is just as much of a subsidy as paying a homeowner to install PV and/or storage. Why shouldn't the residential customer be able to benefit as big business does.

People also complain about the "unfairness" of paying rebates or incentives for energy efficiency upgrades and programs. The fact is that it's cheaper to buy efficiency than it is to pay for additional generation, and more wires and poles. You can argue all you want but it's a fact. That's why the regulatory authorities mandate these programs. The utilities don't want to do it because they'd like to sell more electrons. In CA the profit margin that the regulated (monopoly) utilities are guaranteed is based on capital expenditure. So you can be sure that they would love to build new power plants and more wires.

In prehistoric times, you remember them, in the previous century, where you had the energy company running the generators, this worked pretty well. They used reservoirs, typically to store power.

This system worked pretty well. There weren't brownout. Power was cheap. And I don't think there were as many cases of overworked powerlines burning down the state.

Yeah it worked pretty well for a while. Like I said, if everybody had their own generation, you wouldn't have any overworked powerlines. And it's not overwork that causes the fires, it's being blown down by the wind. And exacerbated by hot dry weather which, I know you will never acknowledge could be a result of anthropomorphic climate change, but there's a pretty strong consensus that it is, at least partially. But again, the system works best and more efficiently with more distributed generation. Especially the kind that doesn't produce GHG's.

Today, we have millions of tiny little generating plants, very expensive tesla powerwalls.

That's the whole idea. But I know you're much too fucking dense to get it. Mine's not a Powerwall, BTW.

And reservoirs are great. They are still being used, as a matter of fact, but you can't just put one anywhere. Obviously not on my rooftop or in my backyard. And hauling a big-ass piece of concrete up a track or a cable would be pretty ridiculous on a residential property as well.

But upper middle income hippies feel better, because they are doing their part....with a little help from fellow taxpayers, to save the planet!!!!!!

Go fuck yourself. But try cracking a book or two and learn how this stuff actually works when you're done.

But expensive light weight storage in stationary applications makes zero sense for anyone tied to the grid. Large scale gravity storage is far cheaper and better environmentally. But it ain't about being cheap or environmental. It is about Big PV and Big Li Ion.

See above. Large scale gravity storage is not cheaper or better environmentally, except in your damaged mind. Where do you propose putting enough of it to have any discernable effect? Please be specific.

And my battery is not Li-ion.

I find it kind of ironic that someone in Local, would site emergency power as a benefit of having his own storage.

Why not? You have your hurricanes and blizzards. We have our wildfires, earthquakes and high wind events. We've been told that we could be subject to "public safety power shutoffs" in high wind events when there's an increased fire risk. After the fires a couple of years ago the utilities are doing anything they can to avoid more liability. That includes preemptively deenergizing any circuits that might present a danger of having wires go down.

When was the last time one of those hit SD?

They don't. 30 years ago, power outages were a thing in places with shit weather and 3rd world power grids.

Quite the opposite. We had our power shut off in 2017. And several warnings since then.

You don't have the former, but the latter is becoming a thing, thanks to your Rube Goldberg system.

Even if stationary Li Ion was economically wise, I would use the same argument used against oil. That argument is yeah, there's enough....for now. But what about in 50 years?

This push to ramp up Li Ion for the short term price benefit, very well may become a problem when it gets rare or when East Bumfukkistan turns off the Li tap.

Seems to me that every last bit of chemical electron captivity done today should be for portable storage (phones, cars, dildos, etc....) rather than ensuring Mikey has free interweb pron during the next upper mexico blackout.

If you actually took the time to learn something about this (not just from Hannity and friends) you'd realize that you are completely off base.

The pathway to a more stable grid is by moving away from centralized generation. Not completely, but enough to increase the stability and reliability of the system.

And that "portable storage" in cars, once it's degraded to the point where its energy density is too low for cars and stuff, can be re-purposed for stationary application where it doesn't matter if it's a little heavier.

[Mikey]

One thing I didn't mention...

So, you actually buy cheap electricity, store it, then sell it back when the market is favorable to do so?

The answer to this is...no.

I buy cheap electricity at night and use it in the afternoon when it would be expensive. But if you had actually read my post, you might have figured that out.

The utility doesn't allow you to you to discharge the battery into the system for that very reason. Otherwise you could just go out and buy a big-ass battery, charge it at night, and make money all day long. If you look at my second chart, you might be able to figure out that my usage essentially zeroes out after 4 pm until midnight. Any electrons I put back into the system are coming from excess PV production during the daytime. My Rube Goldberg system is smart enough so that it's programmed for this.

[smackaholic]

Maybe my pea-sized brain did misread something.

What type of battery do you have? I know the powerwalls are Li Ion, which seems kind of dumb, especially if made from virgin batteries.

You do make a good point about repurposing diminished car batteries. Is that regularly done?

Once the battery is at this point, does it have enough life left in it to make repurposing to stationary duty worth-while?

As for gravity storage, much more compact systems are being developed.

Compact enough to sit out there next to the shade tree and cement pond?

Maybe not.

But compact enough to place in neighborhoods, I would think. And their lifetime is a lot longer than any chemical storage. I think they are the future for decentralized grid storage, not zillions of batteries in peoples garages.

[smackaholic]

You mention a "tangible economic benefit".

If this is the case, ought it not stand on its own, without a government subsidy?

If what you say truly is beneficial and saves people money, it shouldn't require government bribes.

[smackaholic]

https://getpocket.com/explore/item/the- ... ket-newtab

This is what all that "green tech" buys us.

[Innocent Bystander]

https://getpocket.com/explore/item/the- ... ket-newtab

This is what all that "green tech" buys us.

This is a great read. Saved as .pdf.

[Mikey]

https://getpocket.com/explore/item/the- ... ket-newtab

This is what all that "green tech" buys us.

Horrific, no doubt. And China has been pretty bad about implementing any kind of environmental protection. But what does it have to do with batteries? It talks about "rare earth metals" but lithium isn't a rare earth metal. You're confusing "green tech" with "consumer electronics." Pretty much different issues, aren't they? If you're going to bring up the environmental impacts of mining lithium, at least get your facts straight. And yes, it does present challenges in "shithole" countries. But it also presents an opportunity to funnel some money into these countries and, if done right, have a positive effect on their (mostly) corrupt governments and their extraction methods. That's not the capitalist way but wait, aren't you a right wing capitalist except when you seen an opportunity to criticize anything that might go against the fossil fuel industry?

And BTW, I assume you have a smartphone? Doesn't the equipment you make a living servicing depend on a lot of these rare earth metals? Why don't you quit your job and throw away all of your electronics if you're so concerned?

Here's another picture of some environmental devastation.



Not China, though. Baton Rouge.

This is what our fossil fuel dependence buys us.





Canada tar sands.




Fracking in Wyoming

[Mikey]

Mikey, does SDG&E send you one bill a year for usage? My neighbor has had solar for about 2 years and told me the other day that they got a 600 bill for the year in September after only getting 10 or 11 dollar bills monthly. She said that SCE told her it was for the overages for the whole year and asked me if I got those. I've had my panels up for over 10 years now and have never received any bill monthly or yearly from SCE that was over 6 dollars during that time.

I get a bill every month that shows how much I've used and the net charges for the month, which includes a $16 meter charge to be on the EV TOU rate. But it also says not to pay it because my "true-up" is after the May billing cycle. Any charges or credits accumulate for the whole year, and then I pay the balance at the end of May. I usually build up a credit in the spring and early summer when there's plenty of sun and I'm not using any AC. Then I work through the credits in the late summer and winter, when there's not nearly as much PV production and I'm using electric heat.

SCE may do things differently.

Before this year I was paying about $2,000 per year for the true-up. In May of this year I actually carried over a credit because of the clean fuel rebate for my EV. And now I've added more panels and the battery, but also a heat pump heater and water heater. So, we'll see how it works out in May.

And don't worry, 'holic, I'll have an answer for your post at some point. I just need to put together a line-by-line rebuttal to your obvious ignorance. It could take a while because there's so much to work with.

I added more panels about 5 years ago but I do not have any type of storage. I'm curious why I've never had one of those true up payments/bills in over 10 years of, maybe all of my panels are making more power than I ever use.

I'm not too familiar with SCE's residential rates, more so with their Commercial and Industrial rates. Do you know if you're on NEM (Net Energy Metering) 1.0, or 2.0? NEM 1.0 was in effect until 2017 and is a tiered rate (your rate goes up as your usage goes up). NEM 2.0 is a TOU (time of use) rate where the rate varies by time of day and seasonally. All new solar installations are automatically NEM 2.0, and NEM 1.0 is no longer available. If you have an older system you could still be grandfathered into 1.0. I had to change to 2.0 when I first added a battery early last year. Do you have a copy of your bill? If not you could probably log onto your account at SCE to find out. A lot of people wanted to keep their NEM 1.0 rate but I've found that you can work the TOU to your advantage if you know what you're doing.

[smackaholic]

Mikey, yeah, man has done a pretty fair job of shitting up the place for centuries. But we evil capitalists have done a pretty good job of trying to turn that around for about 50 years.

As for those tar sand pics, I read an article recently by some Canuck from the area who said that The place was a toxic wasteland for centuries, but after they suck all the oil off, they spread some dirt and now these areas are kind of nice and support wildlife.

As I’ve said many times, I’m not against PV or other allegedly green forms of power. I’m a big hydro fan where it makes sense.

But when I see people hanging huge, very pricey chemical electron storage devices on their garage walls at someone else’s expense, I get a little annoyed.

Still waiting to hear what your chemistry of choice is for batteries?

NiCad or Nimh?

Or are you going old school with Pb?

A few years back I read something about salt water batteries. Absolutely horrible watt/lb numbers, but it might be viable if you have the space for it.


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[Mikey]

I guess one man's virgin forest could be another man's toxic wasteland...or something.





etc.


We all have our priorities, I suppose.

My batteries aren't Li-ion...but that doesn't mean they contain no lithium. :wink:

Lithium Iron Phosphate (LiFePO4) has a lower charge density than Li-ion, but that's not so important in a stationary system.

They degrade more slowly, allowing more charge / discharge cycles. Probably twice the lifetime.
Also important, is that they are a lot more stable and have never been known to spontaneously combust and burn down anybody's house or pants pocket.

https://blog.epectec.com/lithium-iron-p ... advantages

This is the current version of what I have. I wouldn't put it in my living room, though. The on-board cooling fan is a little too noisy, and there's a fairly large (probably 2") conduit coming out of it and feeding a sub panel on the wall next to it. It's in the garage directly on the other side of the wall from my main panel outside.

https://sonnenusa.com/en/sonnen-ecolinx/