Solar photovoltaic on the house as an investment

[meierlde]

An interesting piece from the IEEE spectrum on distributed solar in Az. Note the move to paying wholesale for energy from the home. Also note the solar power folks looking at distributed power, and finally that Arizona Public service is looking to install solar on 1500 rooftops with the output under the utilities control: Utilities and Solar Companies Fight Over Arizona’s Rooftops - IEEE Spectrum

[NW-Bound]

Quote:

Originally Posted by skipro33 Tahoe spilled it's natural rim a few weeks ago. Into the Truckee River, it's natural outlet. Not much, but It did. The lake rim to spill is 6,223 feet. As of this morning, it's at 6222.95 feet...

We were there on 6/3, and the water was a few feet low. So, it looks like there was some rain or inflow after we left.

Back on energy storage, the local utility SRP (Salt River Project), one mentioned in the IEEE Spectrum article quoted by Meierlde above, also manages the water shed of the Salt River. For energy storage, it pumps water upstream between a series of lakes. Its largest turbine used as a peaker is rated at more than 100 MW. That sounds big, but is just a fraction of the total power produced by SRP. And SRP is not the only electric utility serving Phoenix.

Geographical features allowing upstream pumping for energy storage like this do not occur often.

[skipro33]

Electric company I worked at will be building pumped storage as peaker power. We use wind generated electricity at night to pump water up hill to run through a hydroelectric plant during peak hours on hot afternoons.

It's called the Iowa Hill Project

Here is a short video explaining the project and how it will be accomplished

https://www.youtube.com/watch?v=Xk3RKX8K2vo

[NW-Bound]

What I am curious to know is the investment cost of pumped water storage systems. There's a large initial cost, plus some maintenance and operating costs. How's that relative to the current small-scale battery cost? I am sure the numbers are available, but just not accessible to laymen.

[skipro33]

I don't know what the Iowa Hill project will cost, but it won't be cheap. That is all going to be completely underground, the generator and the upstream 'lake'; none of it will be dectectable from above ground that there was anything built there. 400 megawatts of generation is a HUGE plant. What a cavern they are carving out of the mountain. Then a lake built under ground above it!! I think the lake above will be built, then covered.


I can't imagine a battery stack that could stand a 400 MW draw. That would be a site to behold.

[NW-Bound]

Lithium batteries can easily stand a 1C discharge. That is, Elon Musk's announced 7kWh home battery should be able to do 7kW, and it requires 57,000 of them at a cost of $171M retail to do 400MW, though they would last only 1 hour. Another big question is how many cycles the battery will last.

I think a nice feature of a distributed residential storage system is that it will alleviate the hardship put on the distribution grid. All that is needed is an inexpensive battery that can last.

[skipro33]

Robert A. Heinlein wrote about Shipstones in a book he wrote titled 'Friday'.
In the story, Shipstones come in various sizes, some large enough to power ocean freighters and even spaceships. Others are smaller, intended to power a home or even a small tool, like a drill. They last forever. The guy who invented them won't tell how he does it and when anyone attempts to reverse-engineer them, they blow up.



I imagine science fiction is more than just prediction of the future, it's a glimpse into the future. Storage of power will evolve into something that will totally change how we see energy.

Here's a potential on the horizon;
http://www.technovelgy.com/ct/Scienc...p?NewsNum=1179

[ERD50]

Quote:

Originally Posted by skipro33 Electric company I worked at will be building pumped storage as peaker power. We use wind generated electricity at night to pump water up hill to run through a hydroelectric plant during peak hours on hot afternoons. It's called the Iowa Hill Project ...

Quote:

Originally Posted by NW-Bound What I am curious to know is the investment cost of pumped water storage systems. There's a large initial cost, plus some maintenance and operating costs. How's that relative to the current small-scale battery cost? I am sure the numbers are available, but just not accessible to laymen.

Yes, it is interesting, and probably a good thing, but I didn't find much background info. It says 400MW capacity, but how many MW-hours can it provide each day? Cost was listed at $800M, but we need the hours to make sense of that. And how large of a grid is that 400MW on (perspective)? What is the environmental impact of a new 100 acre reservoir?

SMUD begins feasibility work on $800M pumped-storage system in the Sierra - Sacramento Business Journal

They list efficiency at 80%, so it wastes 20% of any stored energy, bring those costs up by that factor, plus amortizing construction costs.

Does that grid actually have a surplus of variable renewable energy that needs to be stored?

It looks like this is really more about cutting back NG peakers in the late afternoon and evening (they mention a 5:30 PM peak), which sounds good, but...

Look at it this way - they need NG peakers arround 5:30 PM, these can be scaled back with the pumped storage. But, what if there is little excess wind at night? Where are they getting the energy to pump this back up? Would a high % of energy to refill the reservoir come from baseline coal overnight? If so, this might not be so environmental?


So the key is whether they really have excess renewables (or expect it in a few years when this can come on line)? And how does that factor into the cost of renewables?

Really back-of-the envelope calculation here: Imagine a grid where we already have solar just hitting the daily peaks. To add more, we need to store/shift that power from the peak. Say you could use this 400MW capacity to store and shift a few hours of a solar farm output most days (this assumes it has the MW-hour capacity to take the entire output, I'm just basing this on peak capacity of each). A 400MW peak solar farm, at ~ $1/watt installed for the solar farm - their $800M pumped storage estimate adds $2 per watt to the system cost. Increase by 20% for losses, plus whatever operating costs there are. I don't know if that calculation is in the right context to make sense, but it could be close? Triples the cost of solar? This is why I question these comments that solar is now on par with coal - not when you add in the cost of making it available when we need it.

And we still have not dealt with days of storage, like many parts of the country would need. So we still need the capacity (and capital costs) of all those peaker plants, in many (most?) cases.

And big picture wise, how much of this kind of storage can be applied country-wide? There is some background at David MacKay FRS: : Contents, I may dig into that later.

-ERD50

[NW-Bound]

We are still working on storage solutions to bridge the gap of a few hours between peak supply and peak demand. Storage that lasts a few days is currently beyond our reach. Large reservoirs would be nice, as the storage capacity (the kWh) is independent from the size of the equipment (the kW). So, pumped storage cost will not scale up with capacity like electrochemical batteries do. On the other hand, battery capacity can be added incrementally, requiring no massive initial investment.

Most likely, we will have an assortment of technologies, each to be used where it makes most sense.

I thought about solar in Hawaii where electric cost is high due to import of oil (or coal?). Even if solar does not reduce the size of the power plant, hence no reduction in capital equipment, perhaps it still helps lowering the operating cost as the plant does not burn as much expensive imported fuel.

[Mulligan]

This is very interesting but too complicated for me. I say lower the KW cost a small bit and jackup the monthly connection fee to keep everyone paying their fare share to maintain viability of system. If they don't like it, then go completely off grid and avoid the monthly fee.


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[Nords]

Quote:

Originally Posted by Mulligan This is very interesting but too complicated for me. I say lower the KW cost a small bit and jackup the monthly connection fee to keep everyone paying their fare share to maintain viability of system. If they don't like it, then go completely off grid and avoid the monthly fee.

Hey, us "solar freeloaders" helped HECO avoid building another generating plant. Instead they used their extra capital to boost the CEO's salary.

If we give utilities a chance to behave responsibly and they screw it up, then I'm going to oppose paying my "fair share" so that they can waste everyone's money.

Maybe a utility should be able to figure out their cost of producing power and their cost of maintaining the grid, and bill us accordingly.

[ERD50]

Quote:

Originally Posted by Nords Hey, us "solar freeloaders" helped HECO avoid building another generating plant. Instead they used their extra capital to boost the CEO's salary. If we give utilities a chance to behave responsibly and they screw it up, then I'm going to oppose paying my "fair share" so that they can waste everyone's money. ...

I'm guessing 99% of the population would use that rationalization to oppose their "fair share" of taxes as well.

Quote:

Maybe a utility should be able to figure out their cost of producing power and their cost of maintaining the grid, and bill us accordingly.

Like this? Careful what you wish for - with almost half the bill going to delivery, payback on solar will take a hit.

[REWahoo]

Quote:

Originally Posted by Nords Maybe a utility should be able to figure out their cost of producing power and their cost of maintaining the grid, and bill us accordingly.

That's exactly what our Co-Op does, but I've been with them for so long I assumed that's what they all do.

Our monthly electric bill has four components:

Availability charge - a flat charge of $25.00 "just because"
Delivery/Distribution charge - a per kwh charge for constructing and maintaining the grid
Energy Charge - a per kwh charge for the power they purchase
Fuel Cost Adjustment - a per kwh charge to increase the bill a bit more

Last month the three per kwh charges totaled just over $0.09 and $0.02 of that was for delivery/distribution. The payback numbers for solar don't work for us.

[Mulligan]

Quote:

Originally Posted by Nords Hey, us "solar freeloaders" helped HECO avoid building another generating plant. Instead they used their extra capital to boost the CEO's salary. If we give utilities a chance to behave responsibly and they screw it up, then I'm going to oppose paying my "fair share" so that they can waste everyone's money. Maybe a utility should be able to figure out their cost of producing power and their cost of maintaining the grid, and bill us accordingly.

Well since NEE is coming in and buying out your good HECO friends maybe they will be able to drive price down and bring some efficiency to your expensive grid system down there. I think that is their goal and maybe adding a solar farm to provide electricity. I love buying electrical utility preferred stocks, but you Hawaiians take that solar too seriously for me to invest in the local power plant. I want my dividends safe and secure.
Our local rates are 12 cents summer and a bit under 8 cents in winter with a flat $8 line fee. Solar isn't going to overrun us here anytime soon so I load up on the safe preferreds from the local Ute.


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[NW-Bound]

Quote:

Originally Posted by REWahoo ... The payback numbers for solar don't work for us.

Will it work if carbon tax gets levied?

I have not heard much about it recently.

[NW-Bound]

Quote:

Originally Posted by Mulligan ... Our local rates are 12 cents summer and a bit under 8 cents in winter with a flat $8 line fee...

In the summer, I am paying 7.41c /kWh during off-peak hours and 22.26c during on-peak. I do not think this cost differential is real, meaning I think they undercharge the off-peak and overcharge the on-peak to entice people to cut back consumption during peak hours.

So, I program my pool pump to run when electricity is cheap, and also put a timer on the water heater to lock it out during peak hours. Every month, they tell me how much I save compared to the bill I would have had under the conventional flat rate (yes, that is one of the options). I saved $13 last month.

An individual is entitled to do what is advantageous to himself, as long as he plays within the rules. Who does not take tax deductions and credits that he is allowed?

[Mulligan]

Quote:

Originally Posted by NW-Bound In the summer, I am paying 7.41c /kWh during off-peak hours and 22.26c during on-peak. I do not think this cost differential is real, meaning I think they undercharge the off-peak and overcharge the on-peak to entice people to cut back consumption during peak hours. So, I program my pool pump to run when electricity is cheap, and also put a timer on the water heater to lock it out during peak hours. Every month, they tell me how much I save compared to the bill I would have had under the conventional flat rate (yes, that is one of the options). I saved $13 last month. An individual is entitled to do what is advantageous to himself, as long as he plays within the rules. Who does not take tax deductions and credits that he is allowed?

I had not ever bothered to check our official rates until I just wrote them above, though I had a decent idea. Interesting for me there is no peak or off peak charge for summer. Which is odd because that is when they roll in the dough. Although I just did a blended guess above they actually have peak winter rates of 8 plus cents for first 750 KWH and 5 plus cents over 750KWH. So they actually encourage you to turn up the heat. Maybe I will!
Income restricted people get a nice deal. 3 cents a KWH.


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[NW-Bound]

Here, they have 3 different price plans for residential accounts, plus one for solar owners. Did not see anything for "income restricted" people.

My income is quite restricted right now, and I already have to create more myself via Roth conversion. Wonder if I could get cheap electricity for my AC if I lived in your state.

I can see the newspaper headline now: "Millionaire early retiree sucks up thousands of cheap kWh for his 5-ton AC".

[Mulligan]

Quote:

Originally Posted by NW-Bound Here, they have 3 different price plans for residential accounts, plus one for solar owners. Did not see anything for "income restricted" people. My income is quite restricted right now, and I already have to create more myself via Roth conversion. Wonder if I could get cheap electricity for my AC if I lived in your state. I can see the newspaper headline now: "Millionaire early retiree sucks up thousands of cheap kWh for his 5-ton AC".

The tabloids would love running that headline.


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[meierlde]

Quote:

Originally Posted by REWahoo That's exactly what our Co-Op does, but I've been with them for so long I assumed that's what they all do. Our monthly electric bill has four components: Availability charge - a flat charge of $25.00 "just because" Delivery/Distribution charge - a per kwh charge for constructing and maintaining the grid Energy Charge - a per kwh charge for the power they purchase Fuel Cost Adjustment - a per kwh charge to increase the bill a bit more Last month the three per kwh charges totaled just over $0.09 and $0.02 of that was for delivery/distribution. The payback numbers for solar don't work for us.

Basically the same kwh charges in the municipal system I live in about .02 for distribution and .06 for energy, as well as a base charge of about 6.00.
As with many coops the goal is the lowest cost for all customers thus the flat rate.