Solar Roadways - Another farce

[Scout26]

Long-ish but explains why solar roadways are utter BS.

https://www.youtube.com/watch?v=H901KdXgHs4

[Hutch]

You're like, totally harshing on my mellow, man.

[TechMan]

Modified the link to take out the time start.

[Scout26]

Modified the link to take out the time start.

Thanks, I didn't know I did that/it was in there. 

[onions!]

Interesting.
I stopped listening after a minute but it did make me wonder a bit.

I'm surprised that someplace like Google or Disney hasn't replaced their pavement,at least in the pedestrian areas,with something like this.

[TechMan]

He has some good science behind it.  But still it is green!  Where is that sarcasm smiley?

[charby]

Interesting.
I stopped listening after a minute but it did make me wonder a bit.

I'm surprised that someplace like Google or Disney hasn't replaced their pavement,at least in the pedestrian areas,with something like this.

I can something like this for walking areas, maybe even the medium on highways, roof top patios, I just can't imagine it as a driving surface. I just think of metal that tires pick up and destroying the glass.

[Ben]

With the whole "LED signs" part of the modules, maybe they should try and prototype it on the Vegas strip, where you already have a bunch of Casinos flashing neon signs everywhere, lots of electricity use, and some of the best conditions for solar input. He could get the casinos to go in on it with him for the tax deduction. Not sure about the tech for prime time and highways. I would worry about the traction capabilities where it's icy, and the modules ability to prevent ice through heat (the video makes a good point there, I think).

[RevDisk]

I can something like this for walking areas, maybe even the medium on highways, roof top patios, I just can't imagine it as a driving surface. I just think of metal that tires pick up and destroying the glass.

Solar panels are currently not exactly cost effective. Subsidies can barely make them cost effective. Compared to grid power. Sometimes, you need low voltage in a place uneconomical to run grid power. Then it can make absolute sense. So, this could make sense for powering a sign on a sidewalk. Or looking pretty in your backyard.

Too dangerous:
1. It's covered in glass. It will break eventually. Even if it's safety glass and breaks into safe, non-sharp edges, you now have tires in direct contact with either PV cells or printed circuit boards. Either is very bad.
2. It's glass. Even if the initial traction is good, it will grind away quickly. That's why glass is used for optical transparency.
3. It's glass. Glass is non-porous. Which means mandatory hydroplaning.
4. It contains electricity. Electricity must be handled very carefully when near water, oil, etc.
5. It makes road maintenance significantly more interesting, as you now add a much higher risk of electrocution.

Extremely bad for environment:
1, Asphalt is extremely recyclable (99% efficiency, which is awesome) and starts as a waste product (reusing something otherwise ending up in a landfill).
2. This would not use recycled glass (poor transparency), so you'd need to use and toss a LOT of glass for one time purposes. It'd also eat up LOTS AND LOTS AND LOTS of plastic, metal, etc that would not be easily recycled. Same with the PV cells. All of those parts are very expensive (in this purpose), are either not recyclable or partially recyclable. Re-usability would be minimal.

[Nightfall]

But... but... but... the video that everybody has been watching about this was so flashy, and upbeat, and filled with sound bite points completely unaccompanied by in-depth analysis of the issues with this half-baked idea! HOW COULD IT NOT BE TEH FUTURES?!?! 

[charby]

Solar panels are currently not exactly cost effective. Subsidies can barely make them cost effective. Compared to grid power. Sometimes, you need low voltage in a place uneconomical to run grid power. Then it can make absolute sense. So, this could make sense for powering a sign on a sidewalk. Or looking pretty in your backyard.

As technology improves the price comes down.

My buddy just spent $6800 on a system that generates 4000 watts of power when the sun shines. He figures it will pay for itself in 6-7 years in the power that is sold back to the power company. He did his own install, so that is just equipment costs. He installed on the southern facing roof of his corn crib. 8:50 pm last night as the sun was low in the sky he was still kicking out over 3000 watts.

[Brad Johnson]

Current generation panels are actually pretty decent, though still a ways from being efficient enough to gain widespread ecenomic acceptance.  Fifty-ish percent operating efficiency seems to be the magic number for getting a harder look from mainstream consumers.  Given ongoing advances in materials and construction technologies, that number is likely only a few years away.

Thin film cells are the really exciting tech.  Couple thousand sq ft of generating capacity shipped on a roll that would fit in a five gallon bucket.

Brad

[RevDisk]

As technology improves the price comes down.

My buddy just spent $6800 on a system that generates 4000 watts of power when the sun shines. He figures it will pay for itself in 6-7 years in the power that is sold back to the power company. He did his own install, so that is just equipment costs. He installed on the southern facing roof of his corn crib. 8:50 pm last night as the sun was low in the sky he was still kicking out over 3000 watts.

I use PV cells all the time, especially for my microelectronics platforms. I have TEGs and gods knows how many other alternative energy generators laying around.

I use 'em, but I'm not exactly impressed. Aye. I like solar cells just fine. I just don't care for folks who oversell products that under deliver. Trust me, I wish PV cells DID live up to the claims, desires and wishes of the green, hippy and watermellon (green outside, red inside) crowds.

[HankB]

My buddy just spent $6800 on a system that generates 4000 watts of power when the sun shines. He figures it will pay for itself in 6-7 years in the power that is sold back to the power company . . .

I never liked the expression "it will pay for itself" when you have to lay out money NOW. If the sellers were REALLY serious about that, they'd work out some sort of payment plan where the buyer of the system would keep paying the same electric bill he does now (based on his historical use) and the solar system seller would take the difference between his actual grid use and the historical average for that 6-7 year period.

[RoadKingLarry]

When are people going to see the danger?
All these solar cells will eventually deplete the suns energy.

[birdman]

I never liked the expression "it will pay for itself" when you have to lay out money NOW. If the sellers were REALLY serious about that, they'd work out some sort of payment plan where the buyer of the system would keep paying the same electric bill he does now (based on his historical use) and the solar system seller would take the difference between his actual grid use and the historical average for that 6-7 year period.

Pays for itself in 6-7 years actually means it will never pay for itself.
Proper use of pays for itself means the NET PRESENT VALUE of the future earnings is greater than the capital cost.  If someone simply says "$6800/(72-84months) = $/month I'll get from electric company, that assumes a discount rate of 0.
If that were the case, you would see a lot more investments in solar, as its a no-brainer for making money...but alas, even with all the "greed" you don't.  Because accounting for even a moderate discount rate (3-5%) the payoff is 10+ years! which is more than the life of the average panel.

Also, even at 0% discount rate! the above math assumes $81/mo back.  Even assuming he gets 3kW at 9pm, or let's say an average of 24kWh per day on a day without clouds, that is more than likely a year-round average of 50-75% of that (as days are long now, and the sun is high in the sky), or 12-18kwh/day.
Given $81/mo, that's a pay-back (assuming billable and payback are the same) rate of $0.15-0.22/kWh, and that's assuming zero personal usage.

Does your friend live in CA?  Because that's a damn crazy combination of high electricity cost, high average solar angle, and high availability to even achieve that number, which assumes a best case zero personal usage, and then STILL, NPV-wise, is still a poor investment.

[charby]

Does your friend live in CA?  Because that's a damn crazy combination of high electricity cost, high average solar angle, and high availability to even achieve that number, which assumes a best case zero personal usage, and then STILL, NPV-wise, is still a poor investment.

Rural Electrical COOP (Iowa).

[tokugawa]

I have not seen the glaringly obvious addressed.

 Assume all other objections are solved.

What is going to be the power output when it gets dirty?

[birdman]

Rural Electrical COOP (Iowa).

Rural Electrical COOP (Iowa).

Yeah, your friend is taking a bath.
An example of those rates is $0.13-0.15/kWh.
See: http://www.swiarec.coop/content/electric-rates

His panel is 4kW peak, and let's assume its mounted at an angle that gives him 4kW at a sun angle of 50deg (yearly average for Des Moines)

So, let's dig into the details:
Average daylight hour/day in Des Moines is 12 (go figure), however, only 7.5 of those average hours it is actually sunny, so that's 2737 sunny hours per day.
http://www.des-moines.climatemps.com/sunlight.php

However, you mentioned his panel is mounted and not tracking, so that means if its south facing, at dawn and dusk, the azimuth of the sun matters, which is an average of 2/pi or about 63%, so he loses that! cutting down the equivalent full sunlight hours to 1742.

Now the sun elevation changes by about +/-20deg (not the 23.5deg of earth's axial tilt due to atmospheric refraction), and that effect is roughly a few percent, so we won't count it.

So we now have 1742 average full sun equivalent hours, or a yearly generation of 7000kWh.
So, at his current electrical rates, that's a year revenue (or reduction in his normal bill, but same difference) of $958.

So his zero percent discount rate payback, assuming no maintenance and free labor for install, and assuming the "payback" rate is the same as his billable rate (when in fact, since the first 200kwh/mo is the higher rate, its likely that the payback is on the lower marginal rare) is $6800/960, or 7.1 years.

With a discount rate of 3%, the break even is 10yr
5% is roughly 15yr (this, or HIGHER is usually the number one should use when calculating capital investment benefits)
Now, electrical rate increases are likely as time goes forward, which reduces the effective discount rate, so let's factor in average energy price growth (for Iowa, about 1-1.5% lately! year over year), so that reduces the effective discount rate to 3.5-4%, so let's give him the benefit of the doubt and go with a 3.5% rate or about a 11yr payoff.

So, if ANY of the following IS true, the panel is a bad investment:
1. He has a current mortgage that has more than 10yrs left on it at an APR of >3.5%
2. He paid for the panel in cash, and the assumption an average index fund with do better than 3.5% average over the next 10yr is valid
3. He owns a business that has an annual revenue growth over 3.5% and could grow with additional capital.

Now, your average crystalline panel has an output that degrades about 0.5% per year which raises the effective discount rate (note, cheaper amorphous silicon or other thin film panels degrade 1-2+% per year), meaning longer payoff, but has the opposite effect on the comparison to a mortgage, meaning the lifespan issue means if he has a mortgage at more than 3%, with more than 10yr left on it, paying that off is better.

Sorry for the huge digression, but far too many people get sold on the "it pays for itself" without digging into the real financial impact of the capital outlay.

[Doggy Daddy]

I have not seen the glaringly obvious addressed.

 Assume all other objections are solved.

What is going to be the power output when it gets dirty?

And, who will guard the long, empty highways from the independently contracted reclamation experts, pulling up tiles to sell on the black market?

[charby]

Yeah, your friend is taking a bath.
An example of those rates is $0.13-0.15/kWh.
See: http://www.swiarec.coop/content/electric-rates

His panel is 4kW peak, and let's assume its mounted at an angle that gives him 4kW at a sun angle of 50deg (yearly average for Des Moines)

So, let's dig into the details:
Average daylight hour/day in Des Moines is 12 (go figure), however, only 7.5 of those average hours it is actually sunny, so that's 2737 sunny hours per day.
http://www.des-moines.climatemps.com/sunlight.php

However, you mentioned his panel is mounted and not tracking, so that means if its south facing, at dawn and dusk, the azimuth of the sun matters, which is an average of 2/pi or about 63%, so he loses that! cutting down the equivalent full sunlight hours to 1742.

Now the sun elevation changes by about +/-20deg (not the 23.5deg of earth's axial tilt due to atmospheric refraction), and that effect is roughly a few percent, so we won't count it.

So we now have 1742 average full sun equivalent hours, or a yearly generation of 7000kWh.
So, at his current electrical rates, that's a year revenue (or reduction in his normal bill, but same difference) of $958.

So his zero percent discount rate payback, assuming no maintenance and free labor for install, and assuming the "payback" rate is the same as his billable rate (when in fact, since the first 200kwh/mo is the higher rate, its likely that the payback is on the lower marginal rare) is $6800/960, or 7.1 years.

With a discount rate of 3%, the break even is 10yr
5% is roughly 15yr (this, or HIGHER is usually the number one should use when calculating capital investment benefits)
Now, electrical rate increases are likely as time goes forward, which reduces the effective discount rate, so let's factor in average energy price growth (for Iowa, about 1-1.5% lately! year over year), so that reduces the effective discount rate to 3.5-4%, so let's give him the benefit of the doubt and go with a 3.5% rate or about a 11yr payoff.

So, if ANY of the following IS true, the panel is a bad investment:
1. He has a current mortgage that has more than 10yrs left on it at an APR of >3.5%
2. He paid for the panel in cash, and the assumption an average index fund with do better than 3.5% average over the next 10yr is valid
3. He owns a business that has an annual revenue growth over 3.5% and could grow with additional capital.

Now, your average crystalline panel has an output that degrades about 0.5% per year which raises the effective discount rate (note, cheaper amorphous silicon or other thin film panels degrade 1-2+% per year), meaning longer payoff, but has the opposite effect on the comparison to a mortgage, meaning the lifespan issue means if he has a mortgage at more than 3%, with more than 10yr left on it, paying that off is better.

Sorry for the huge digression, but far too many people get sold on the "it pays for itself" without digging into the real financial impact of the capital outlay.

He is with Mid-Land Coop, they are the highest rates in the state.

He took advantage of the tax credit on the panels.

We call his wife the bank of <her name> because won't let him spend a penny just short of filling out a 100 page application.

Her father sells solar systems, he knows how to work the system with the power companies and taxes.

[birdman]

He is with Mid-Land Coop, they are the highest rates in the state.

He took advantage of the tax credit on the panels.

We call his wife the bank of <her name> because won't let him spend a penny just short of filling out a 100 page application.

Her father sells solar systems, he knows how to work the system with the power companies and taxes.

Ah, so "it pays for itself" ...when everyone else pays a little for your system.
Got it. :/

[Boomhauer]

Whoever came up with this bullshit ought to be beaten silly with a tire iron.

It's a video I would watch repeatedly.

[KD5NRH]

I never liked the expression "it will pay for itself" when you have to lay out money NOW. If the sellers were REALLY serious about that, they'd work out some sort of payment plan where the buyer of the system would keep paying the same electric bill he does now (based on his historical use) and the solar system seller would take the difference between his actual grid use and the historical average for that 6-7 year period.

Actually, that's exactly the goal of our financing; get it to the point where the electric bill plus our payment is less than the electric bill before installing solar.  It provides a real incentive to pay so we don't come repo the system.

[Scout26]

I can something like this for walking areas, maybe even the medium on highways, roof top patios, I just can't imagine it as a driving surface. I just think of metal that tires pick up and destroying the glass.

Actually,that's a really bad idea, liability wise.  Glass has a very low co-effiecent or friction, and even worse when wet.  Lots of slip and fall injuries, you'd be paying many, many, many times more just in lawyer fees then any possible energy savings.