Author Topic: EEVblog #1086 - 5 year Solar Power Payback?  (Read 10662 times)

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Offline orion242

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #50 on: May 29, 2018, 12:31:08 pm »
But the cases where it makes economical sense are probably still quite niche today.

Using the car as a grid stabilization or the leftover/replaced batteries?
 

Offline Red Squirrel

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #51 on: May 29, 2018, 10:12:45 pm »
The thing with Lithium ion is that they have to be balance charged and also can't be floated.  It makes the system much more complicated to design as you can't really charge the bank while simultaneously using it, You can, but it's more complex to setup.

With lead acid you have a DC bus that runs at a float charge and put your batteries and loads on it, and call it a day.  Maybe measure mid point voltage to alert for faults, and that's it.

But yeah I imagine over time we will see more charge controllers that can handle lithium ion batteries.  You would get a bunch of leads for each cell bank. 
 

Offline Fungus

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #52 on: May 30, 2018, 05:39:21 am »
The thing with Lithium ion is that they have to be balance charged and also can't be floated.  It makes the system much more complicated to design as you can't really charge the bank while simultaneously using it, You can, but it's more complex to setup.

If you're charging Lithium ion without a proper controller chip that does all this then you're probably heading for trouble anyway.
 

Offline b_force

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #53 on: May 30, 2018, 01:56:48 pm »
Luckily these controllers and other stuff aren't expensive anymore nowadays.  8)
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Offline Barny

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #54 on: May 31, 2018, 02:00:05 pm »
Why always battery storage?

Wouldn't energy storage in rotating masses or compressed air in combination with comressor & air motor an alternative?
 

Offline metrologist

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #55 on: May 31, 2018, 02:17:20 pm »
Those cycles would seem less efficient - too much energy loss, but I guess you could just add more panels.

How much weight how high would = 10kWh?
 

Offline station240

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #56 on: May 31, 2018, 05:26:35 pm »
Why always battery storage?

Wouldn't energy storage in rotating masses or compressed air in combination with comressor & air motor an alternative?

No, as the efficiency of all those is terrible compared to batteries.
Compressed air is 30% efficiency round trip
Flywheel looses a lot of energy if conventional barrings are used.
A flywheel in high vacuum with magnetic bearings is 85% efficiency round trip, but with obvious safety issues using it anywhere bar industrial sites.
Lithium Batteries are 90% efficiency round trip
 

Offline Red Squirrel

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #57 on: May 31, 2018, 05:29:55 pm »
Luckily these controllers and other stuff aren't expensive anymore nowadays.  8)
(it's 2018 people)

The issue is availability too, I only found a few sites that sell solar stuff here in Canada but all the controllers I found only do lead acid batteries.  So you'd have to build your own if you went that route.  I've seen a few videos of people who did it.  I guess if you measure the current going into the batteries, and the current going to the loads, you can do subtraction to figure out how much current is strictly going into the batteries.  Since lithium ion works on several stages of current for charging, and not just a float voltage, so it's important to measure this for each cell bank.   A cell bank being a group of 18650's in parallel for example.  You would need about 12 of these for a 48v system and individual charge leads for each one, and then the load leads to the inverter from the first and last cell.

I was looking at controller chips for fun and it seems most of them don't balance charge, so really not sure how that works.   I guess you would have one chip per cell bank?

I guess another option is to have two or more battery banks.  One would be charging while the other is discharging and it would switch back and forth once in a while.    Heck you could probably even have a very powerful charger that only does one cell, and it would just alternate between each cell.  I imagine there's lot of different ways to do it. 

I'm surprised that lead acid batteries arn't cheaper these days though, seems to me it's such an old and refined tech, and very recyclable, that it would be cheaper to produce.

 

Offline SNGLinks

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #58 on: June 01, 2018, 12:39:34 am »
My system was free! A company leases the space above my roof and fitted the solar panels at no cost.

In return they get the feed in tariff but I get the power generated!
 

Online NiHaoMike

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #59 on: June 01, 2018, 04:06:06 am »
I was looking at controller chips for fun and it seems most of them don't balance charge, so really not sure how that works.   I guess you would have one chip per cell bank?
The balancing BMS boards I have used use individual comparators specifically designed for that purpose. When the supply voltage to them goes above their threshold, they switch on a MOSFET to connect a balancing load.
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Offline Poe

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #60 on: June 08, 2018, 01:05:03 pm »
So I think the takeaway is that, financially at least, it's better to put your money in your savings?

A $5k investment will very conservatively earn over $1k in 5 years.  Equivalent to $1k in the bank and a brand new solar installation.  That's pre-taxed money as well.

That untouched ultra low risk $5k investment would have made ~$2.5k by the time the solar installation paid for itself (assuming you get paid $0.15kWh).

Due to compound growth, after twenty years you'll have ~$13k in the bank.  Best case scenario for the solar installation is that it's still working, generating the same output, and the cost of of electricity has massively increased.  In this scenario, you might maybe make the same amount.

I'm in a new home and considering solar, but it still feels like home solar is still a lot like solar roadways.




 

Offline metrologist

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #61 on: June 08, 2018, 01:57:33 pm »
Zinger!
 

Offline mtdoc

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #62 on: June 08, 2018, 02:54:09 pm »
A $5k investment will very conservatively earn over $1k in 5 years.  Equivalent to $1k in the bank and a brand new solar installation.  That's pre-taxed money as well.

That untouched ultra low risk $5k investment would have made ~$2.5k by the time the solar installation paid for itself (assuming you get paid $0.15kWh).

Due to compound growth, after twenty years you'll have ~$13k in the bank.

Yeah ok, right.  Please tell me where I can find this “ultra low risk” investment that will give me that rate of return. I have a stack of money I’d love to put in such an investment (as would many others worldwide).

Also, one obvious point you’ve missed is that the solar panels and inverter are still quite valuable after 5 years. They could “consevatively” be sold for 50% of their original cost after 5 years.

And BTW, where did this strawman come from that solar installations are simply an investment vehicle and nothing more?
 

Offline Fungus

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #63 on: June 08, 2018, 03:27:38 pm »
And BTW, where did this strawman come from that solar installations are simply an investment vehicle and nothing more?

This!
 

Offline metrologist

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #64 on: June 08, 2018, 03:34:23 pm »
The feeling of being able to stick it to the utilities is quite rewarding. Coincidentally, I opened a Fidelity investment account a little over 6 years ago with $5k (minimum at the time) and it is now worth $6800. I've had it in blue chip tech companies, none of the good ones, mind you. Like Nokia, for example (I was hoping the MS deal would pay out more), and a big part of it just sat in a money market. For someone who knows what they are doing, no contest... My neighbor claims to be clearing $100k annually on his investment accounts. That's all he does in his early retirement.
 

Offline mtdoc

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #65 on: June 08, 2018, 05:18:06 pm »
The feeling of being able to stick it to the utilities is quite rewarding. Coincidentally, I opened a Fidelity investment account a little over 6 years ago with $5k (minimum at the time) and it is now worth $6800. I've had it in blue chip tech companies, none of the good ones, mind you. Like Nokia, for example (I was hoping the MS deal would pay out more), and a big part of it just sat in a money market.

A stock market account as an ultra low risk investment! :-DD :-DD :-DD

Quote
For someone who knows what they are doing, no contest... My neighbor claims to be clearing $100k annually on his investment accounts. That's all he does in his early retirement.

Everyone’s an investment genius in a bull market. :palm:

Look, there are professional money managers earning literally millions annually in client fees who would never claim to be able to produce the “ultra low risk”  ROE claimed.  The closest would be US Treasuries which are currently considered the “gold standard” in very low risk investment for that kind of time frame. Currently, a 5 year T-Bill yields about 2.7% pre tax - well below the 3.7% or so claimed by Poe. And not only is that pre-tax, it is not inflation adjusted - real world return will be much less than that.
« Last Edit: June 08, 2018, 05:20:53 pm by mtdoc »
 

Offline metrologist

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #66 on: June 08, 2018, 05:24:32 pm »
I didn't claim it to be a low risk investment. I said it was a coincidence - the time frame and return to date. That's all. I do not at all think it is a stretch to suspect properly managed investments will outpace your return on a home solar investment. Anything could happen in either market.
 

Offline mtdoc

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #67 on: June 08, 2018, 05:53:32 pm »
I didn't claim it to be a low risk investment. I said it was a coincidence - the time frame and return to date. That's all.

Fair enough - but then it's a coincidence without meaning. One could just as easily mention that they had coincidently won the lottery during that time frame.

Quote
I do not at all think it is a stretch to suspect properly managed investments will outpace your return on a home solar investment. Anything could happen in either market.

Well, I think it is a stretch on a risk adjusted basis - It might or it might not.  In fact at the end of 5 years, a risk based investement could return quite a bit more OR it could result in a loss.  Yes, that is true for "properly managed investments".  I can provide multiple examples if needed.

Solar PV equipment - is NOT a financial investment instrument (despite the fact that there are numerous companies whose entire business model is based on that premise).  Nevertheless, over its lifespan - at current prices for the equipment (which you've locked in once you've purchased it),  it will pay for itself and in most cases return multiples of the initial investment in energy savings.

Depending on the energy market where you live, for a standard grid tie installation, done by a reputable installer at a fair price, it may take 5 years or it could take 10 years to pay off your initial investment.  But after that - for the 25-30 years lifespan of the PV panels and 15-20 year expected lifespan of a quality inverter, you are earning a good return on your original investment.



 

Offline metrologist

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #68 on: June 08, 2018, 07:18:18 pm »
I didn't claim it to be a low risk investment. I said it was a coincidence - the time frame and return to date. That's all.

Fair enough - but then it's a coincidence without meaning. One could just as easily mention that they had coincidently won the lottery during that time frame.


It is just a coincidence in the context of what was said previously, which pretty much mirrored my experience and result to a tee, aside from it not being a "savings" account:

So I think the takeaway is that, financially at least, it's better to put your money in your savings?
A $5k investment will very conservatively earn over $1k in 5 years.  Equivalent to $1k in the bank and a brand new solar installation.  That's pre-taxed money as well.

It's also a coincidence that I am thinking of home solar, and I'm sure that doesn't have any particular 'meaning' either. An average ~5% return is not unlikely and it is nowhere close to the left-field lottery comment.


Quote
I do not at all think it is a stretch to suspect properly managed investments will outpace your return on a home solar investment. Anything could happen in either market.

Quote
Well, I think it is a stretch on a risk adjusted basis - It might or it might not.  In fact at the end of 5 years, a risk based investement could return quite a bit more OR it could result in a loss.  Yes, that is true for "properly managed investments".  I can provide multiple examples if needed.

Solar PV equipment - is NOT a financial investment instrument (despite the fact that there are numerous companies whose entire business model is based on that premise).  Nevertheless, over its lifespan - at current prices for the equipment (which you've locked in once you've purchased it),  it will pay for itself and in most cases return multiples of the initial investment in energy savings.

Depending on the energy market where you live, for a standard grid tie installation, done by a reputable installer at a fair price, it may take 5 years or it could take 10 years to pay off your initial investment.  But after that - for the 25-30 years lifespan of the PV panels and 15-20 year expected lifespan of a quality inverter, you are earning a good return on your original investment.

It could, it could not...a whatif scenario? Jeebus man, what is the overall average return on the type of investments we are discussing? There are losers and winner of course. I would look at index funds and etc., do you have any dataset to argue with? There is generally a predicable  average rate of return, you diversify, and you understand I'm sure... Yeah, rocks could fall from the sky and break your panel - but that never happens, huh? It would be a silly argument against solar - just as silly as the whatif. I'm disappoint!

I think it's down to egos, if one were to really look at the numbers.

Solar PV equipment - is NOT a financial investment instrument...
...for the 25-30 years lifespan of the PV panels and 15-20 year expected lifespan of a quality inverter, you are earning a good return on your original investment.

I never said PV is a financial investment vehicle and argued against that philosophy with you know who, but the original point was made and I appreciate and understand the validity of it. I think people usually install home solar to result in a financial positive, if it is not for technical or political reasons, so it would be foolish not to consider alternate ways of achieving the ultimate goal.

For example, my mum wants to install a small solar system to power an electric fence that presents technical challenges to tie to the grid, and also the city does not allow residential electric fences tied to the grid. No financial incentive at all - it will be a grossly predictable money looser, down to the exact dime.

« Last Edit: June 08, 2018, 07:26:29 pm by metrologist »
 
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Offline mtdoc

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #69 on: June 08, 2018, 08:30:30 pm »

It could, it could not...a whatif scenario? Jeebus man, what is the overall average return on the type of investments we are discussing? There are losers and winner of course. I would look at index funds and etc., do you have any dataset to argue with? There is generally a predicable  average rate of return, you diversify, and you understand I'm sure... Yeah, rocks could fall from the sky and break your panel - but that never happens, huh? It would be a silly argument against solar - just as silly as the whatif. I'm disappoint!

The issue is that Poe stated that there is an "ultra low risk investment" that will magically turn $5000 into $6000 in 5 years.  The reality is that such an investment does not exist. Your coincidental anectdote of your stock market account is completely irrelevant.

Sorry, but if you think index funds are a low risk investment or that looking at average rate of returns (over which timeframe?) or diversification, etc is some magical way to guarantee a low risk ROE then you are demonstrating a level of financial naivety that would be difficult to fully demonstrate without getting way off topic here (learn about VaR as a start).   

If you want datasets, look at any of the major US or world stock market indexes and you will find multiple incidences where a 5 year horizon yielded a very low or negative return.  If you're talking longer time frames just look at the return of the Nikkei 225 (the Japanese market index) since 1990 (28 years!).


BTW - the extremely rare event "rocks falling from sky damaging solar panels" would be covered by most homeowners insurance.  There is no equivalent insurance for the very ordinary and common event of a stock market correction or bear market.

« Last Edit: June 08, 2018, 08:34:20 pm by mtdoc »
 

Offline metrologist

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #70 on: June 08, 2018, 09:54:03 pm »
Are you arguing that an average 5% return in these kinds of investments is a rarity, or even unlikely?

Poe's example turns $5k into $6k in 5 years. I am looking at a 5yr, 3.2% rate CD. You compound that over the term and tell me again what you think about how non-existent an ultra-low-risk investment like this really is. I don't get it :-//

Note this is from a credit union with qualifiers.
 

Offline Poe

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #71 on: June 08, 2018, 10:21:51 pm »
mtdic - I prefaced my comment by limiting the takeaway to the financial aspects.  I'm unaware of any other sensible reasons for an install, but would love to hear them.

So I think the takeaway is that, financially at least, it's better to put your money in your savings?
...

NOTE: The following is regarding the FINANCIAL implications alone..

Data for both investments are well documented.
http://lmgtfy.com/?q=average+401k+return

Inflation-adjusted returns on solar investments are similar to Dave's while the average 401K return is >5%. 

Would love to see the rational and data that discredits this... because, as I mentioned before, I'm considering installing solar panels.  The tax payers aren't going to fund the credits forever.

To judge risk, I looked at typical 'low-risk' Vanguard index performances minus fees for various start/end dates and charted the % of return vs frequency.  Even through the 2004 to 2012 years, the result was basically a bell curve with the most likely outcome being an inflation adjusted compound return of 6%. 

I did something similar with solar installations.  Unfortunately, even when I look at the least risky solar investments (most expensive installations), they still are outperformed by even the higher risk lower average return investments.

I then realized the exact numbers don't matter after twenty years because this is apples and oranges.  One investment is a linear growth while the other is exponential.  Would you rather your $5k earn $600 every year or a compound 5% interest?  Even if it occasionally drops to 1% the latter will always exceed the former. 

Just my thoughts.  Would love to discuss it with someone that hasn't drank the kool-aid and can show me where my logic fails.
 

Offline Bassman59

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #72 on: June 08, 2018, 10:54:47 pm »
Solar PV equipment - is NOT a financial investment instrument (despite the fact that there are numerous companies whose entire business model is based on that premise).  Nevertheless, over its lifespan - at current prices for the equipment (which you've locked in once you've purchased it),  it will pay for itself and in most cases return multiples of the initial investment in energy savings.

Depending on the energy market where you live, for a standard grid tie installation, done by a reputable installer at a fair price, it may take 5 years or it could take 10 years to pay off your initial investment.  But after that - for the 25-30 years lifespan of the PV panels and 15-20 year expected lifespan of a quality inverter, you are earning a good return on your original investment.

I live in Sunny Tucson, Arizona, and we put solar panels on the roof last August. We expect that the payback period will be 5 years, and you're indeed correct, the panel "lifetime" is 25 years, and by that they mean they're still producing 90% of power when new. To me, that means in 25 years they're still working like a champ.

And yes, the expectation is that utility power costs will only increase; how much depends entirely on how much the regulatory commission will allow them to charge. The proposal for my power system showed payback time with assumptions that the utility price will increase 5% per year, 0% per year and -5% per year (this last one is a pipe dream). But I just checked my bills from the last couple of years. The bill separates out generation charges and transmission charges (under the assumption that somehow you could sign up for an alternative generation provider). The increase in generation costs from July 2016 to July 2017 was about 2.17%. The increase in transmission cost for the same time period was 17.6%! And the kicker is that the transmission cost is much larger than the generation cost. The July 2017 bill was $60 for generation and $144 for transmission. So I think that my payback will actually be three years, assuming similar yearly increases in transmission costs.

To address the point made earlier about "if you sell the house in say three years, will you recoup the cost of panel installation?" I spoke to a friend who is a real estate agent and she was like "HELL YEAH." She was clear: if it's a purchased system it's definitely a positive; buyers do want solar power here, and a $15,000 premium over the house next door is in the noise, especially if there is any kind of bidding war where the next bid is $20,000 more. However, if it's a leased system, that's a turn-off, because nobody is quite sure how the leases transfer. (I asked my next-door neighbor, who has a leased system, how that would be handled, and he admitted he did not know.)

One more thing. The installed cost of the system on my roof was $18,700 and we got $6,500 back in federal and state tax credits, so total cost to me was ~$12,000. But this is for a 60-year-old house that had the system retrofitted. For new construction, the cost would be less, as the wiring and the labor are integrated into the home's electrical design and construction. And for new construction that costs $250,000 (high for here), adding $10,000 price is in the noise, really. When I read that California was requiring solar panel installation on all new construction starting in 2020, I thought that was a no-brainer. When houses cost $500k and up, solar power cost is irrelevant. (People pay more for their kitchens.)
 

Offline mtdoc

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #73 on: June 09, 2018, 12:09:11 am »
Are you arguing that an average 5% return in these kinds of investments is a rarity, or even unlikely?

Again, you are demonstrating a lack of understanding of the concept of investment risk. If $5000 invested in the stock market returns 5% or more  over 5 years 50% of the time, 0-5% 40% of the time and < 0% 10 % of the time, then no it’s not a rarity. But that is very, very different than  Poe’s claim of an “ultra low risk” investment yielding 3.7%.

Risk adjusted return is a real thing in the investment world.

Quote
I am looking at a 5yr, 3.2% rate CD.
Show me. What currency? What is the inflation rate in the country?  Not in an insured US bank.  Real returns require that is taken into account. I can probably earn >20% on  a CD on a country whose currency/inflation rate means real returns are likely to be less tha 2%.
 

Offline metrologist

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Re: EEVblog #1086 - 5 year Solar Power Payback?
« Reply #74 on: June 09, 2018, 01:51:03 am »
Are you arguing that an average 5% return in these kinds of investments is a rarity, or even unlikely?

Again, you are demonstrating a lack of understanding of the concept of investment risk. If $5000 invested in the stock market returns 5% or more  over 5 years 50% of the time, 0-5% 40% of the time and < 0% 10 % of the time, then no it’s not a rarity. But that is very, very different than  Poe’s claim of an “ultra low risk” investment yielding 3.7%.

Risk adjusted return is a real thing in the investment world.

Quote
I am looking at a 5yr, 3.2% rate CD.
Show me. What currency? What is the inflation rate in the country?  Not in an insured US bank.  Real returns require that is taken into account. I can probably earn >20% on  a CD on a country whose currency/inflation rate means real returns are likely to be less tha 2%.

I'm not going read your trivial wiki references. They do not at all indicate financial performance, so they are irrelevant. You obviously have some ulterior objective or are talking about something else.

The point is already made in actual performance figures.

I'm referencing a NCUA backed US federal credit union. Qualifying balances are $500k to earn some of the offers I see, so you will not likely see them.

I am not talking about risk assessment anyway. I'm talking about standard returns on the typical kinds of investments being discussed. YOU can even google this yourself. What is wrong with you?

I am reminded of what this forum is about and will go back to it. Hopefully, you will glance at the attached and have a nice day.



 


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