3kw/hr is IN FULL SUNLIGHT. Why have many of you assumed there is 100% sunlight 24 hours/day???

You need to assume about 10 hours of sunlight, max, for summer. If the sun is not hitting the tiles at 90-degrees, they are running LOWER than full efficiency.

Thus, this system would generate 30kw/day, or maybe 900/month. If you're paying $0.18/hr, it saves you $160. So, about 10 years.

But, factor in rain, not peak efficiency, and you're easily up another 30%. So, 13 years.

Now, for our house, we have 2 electricity rates. $0.10/hr for the first 700 kw/h, and $0.18-ish for anything over.

And we ALWAYS go way over a meager 700 kw/h per month - especially in A/C season.

One added benefit: This will help insulate your roof. The energy from the sun that would ordinarily be transferred INTO your attic, will instead have some of it converted to electricity.

Still, there are several promising new solar techs that may come to fruition within the next 3 years. 2 of them promise to have less than 1/3 the entry cost. So, I'd rather wait a bit longer than buy "current" solar tech.

$17k today, "break even" in 13 years.

Wait 3 years, spend $6-8k, break even in 9-ish years.

goglen

Basically, if you were energy-positive more than half the time, the energy company could pay you whatever they chose (or nothing).

A few things to consider:

1. This might have changed in the last three years.

2. The energy company would probably be happy to buy energy from you, they don't have to spend a dime on it and will just pass that cost onto your neighbors.

3. (And this is the one I worry about) Think about the effect of more and more people slipping off the grid, the income loss by the energy companies will increase year after year. They WILL make up this loss:
a. They will increase rates.
b. They won't buy back excess power from home owners (at a good rate anyway).
c. They will lobby congress to drop the credits or tax solar/wind/etc. products, keeping the ROI at least even with buying power from the energy companies.

Sorry, long post. Just consider the political/economic landscape outside of the homeowners control.

Shrike

If you want to know how much a Solar System puts out you have to look at a number called "Peak Sun Hours" or "Solar Insolation" search for AEE (a great solar distributor) and one of these terms and you should find a pdf containing a list of values of many US locations.

Solar Insolation is the number of watt hours per kilowatt installed solar panels- a 3kW system multiplies this by three. This is in DC Power- your home uses AC power and a box called an inverter is needed to convert DC to AC. To account for this and other inefficiencies we include an adjustment in our calculation, .74 in this case.

So our final equation given my home of Portland, OR's Insolation of 4.03 (same as Corvalis, OR) and 365 days in a year.

4.03*.74*365= 1.08

A 3kW system in Portland will produce:

3kW*1.08= 3265kWh per year,

simple.

DrNick

depending on the system, it takes about 4 years to recoup the energy cost it took to make the actual product - the rest is free sustainable energy.

The electric companies are not going to pay you back retail price for putting it back into the grid. They pay you a fraction. Why should they pay you full price when it's their infrastructure you're using?

Wind does not come with fed credits like solar does.

It still takes credits to make solar competitive, but with the obvious escalation of energy prices, early adopters are ones who stand to gain as they will be immune from the fluctuations and will have taken advantage of the early-adoption rebates available. Yes, risk is involved, but the tech has already been proven - just a matter of taking the plunge.

These are all economic variables - add environmental variables in the fact that we don't live forever - let's make our life count and not our pennies; solar and sustainable energy looks awfully good!

zarchitect

Based on what I have read on forums, 15kwh/day is about the average for a family of 4 using incadessant lights (switch to the fluorescents and that drops to almost 10!) 15x30 = 450kwh.

Oh, by the way lights only make up about 5% of your electric bill so switching to fluorescents doesn't really save you that much.

baltwade

rimplestultskin

Up until recently solar cells made no sense ecologically, only financially (if you can figure or bear a 15 yr ROI)...
Most current solar cells use very expensive materials and the energy they produce does not equal the energy used to produce them. Regardless of the cost of the cell to the consumer... that is a market price and profit driven.
If all cells were cheap and produced more than they would consume, we would all have solar roofs today. In fact they would have been mandatory decades ago. Just as minimum insulation standards exists.

Right?

THINK.

aec007

"Will the energy they produce equal or exceed the amount of energy it cost to produce them over their usefull lifetime....?"

Of course they will. If they were made and energy was invested into their manufacturing, the corporation doing the investing is at LEAST going to get their investment back from the purchase price.

If they can produce enough energy to equal their purchase price, then they have produced more energy than was originally invested in them by the manufacturer.

Your argument is flawed, though commonplace. THINK it through.

SMSDHubbard

If we assume that 50% of the year we will have full sun we get roughly 186 days. Also given that the average number of daylight hours is 10 (summer is longer, winter is shorter and some regions are different entirely and should have their own analysis done)

So we get 186*10= 1860(daylight hours) / 12(months= 155 daylight hours per month.

155x3kwh = 465kwh per month.

But wait... what about cloudy/partially cloudy days? does it just stop working? Nope! it will run from 20-80% efficient depending on the specific day so if we split that difference we're looking at 50%

so 155x1.5(50% efficient)=232.5

Total kwh per month = 697.5

Based on what I have read on forums, 15kwh/day is about the average for a family of 4 using incadessant lights (switch to the fluorescents and that drops to almost 10!) 15x30 = 450kwh.

THE CHASE:

Average use for family of 4: 450kwh/month
Total power generated = 697.5kwh/month
Surplus = 247.5
Average cost per kwh = $0.12
Payment from electric company/month = $29.7
Money saved = $54
Total money per month = $83.7/month

Taking the approach of "I have to do it anyway, might as well upgrade" as my viewpoint:

Average roof size = 3500sq ft
Cost per sq ft for strip and re-shingle of cost for asphalt shingles = $4.00

Average Total cost for standard re-roofing = $14,000
Total cost of using photovoltaic cells = $17,500
Difference = $3,500

$3500 is what I need to recoup.

$83.7x12=$1004.40

The $2000-$5000 per year tax break means that my ROI on this is 1 year... less if power prices go up, I change my lightbulbs, add insulation, re-caulk windows or any combination of them.

So assuming a $3500/yr tax credit+1000 = $4500/year of income. in 4 total years it pays off the new roof (that I had to add anyway) of $14,000.

Bear in mind as well that a better shingle will put my overall roof cost much higher.

Magiksreal

In short, yes. You've been fed too much Limbaugh/FauxNews. proof is here(hopefull the link is not blocked- if so its Deptment of Energy):

[www1.eere.energy.gov]

You are right about the Ethanol issue. Its greenwashing designed to make farmers and the uninformed happy.

As to the switchgrass, the productivity ratio justifies its use. there are other alternatives (even factoring in the land and wather costs). Basically any native cellulose based products can be used. The most logical is to use native species to do that as they require much less fertilizer, insecticides, etc. So will I be annoyed if we have huge swaths of prarie grass growing in the midwest? Not at all.

ARP

Bob_of_Mars

Will the energy they produce equal or exceed the amount of energy it cost to produce them over their usefull lifetime....?

They might look green... but they might not be green.

Sort of the bio-fuel Ethanol dilemma.
Corn-based Ethanol only produces 3 ~ 5% more energy that it takes to make it and uses lots of water and land which do not account in the energy ratio.
Switchgrass Ethanol on the other hand produces 450% more energy than it consumes... but still uses land and water...

Do these tiles generate more electricity in their lifetime that it took to create them? and how many non-energy related resources / polution is created in their manufacturing?

Careful before you jump into the "green is good" bandwagon....

:)

aec007

In order to provide 1/2 of my electricity. ONLY 1/2 by 3 different estimates I need to spend $27k to save $318 a year. 48 years to break even. There is no reason other than feel good about yourself. But don't bitch about your retirement or savings if you are foolish enough to do this. You obviously have more dollars than sense.

chicago25624

Imagine how different things could be if every house had this on their roof within the next 25 years or so.

Next up.... cars made out of solar paint.

graham1010

I H8 HOAs. A whole lot.

Brian B

Boognish

Let's say in my area the average cost is $0.10/kWh.
This 3kW system provides the equivalent of $0.30/h.

Assuming an average of 8hrs of sunlight for 300 days / year (probably optimistic) this equates to $720 worth of electricity per year.

At that rate it would take 24 years to completely pay for itself, not including resale value.

Now, if you factor in energy price hikes it could shave 7-10 years (or more) off that, and you are probably within the lifespan of the product.

I'd probably buy this. Folks in Cali and other high-rate areas should definitely consider it.

up2l8

MrSmoofy

Most sunny states, like Florida and California, have laws that prohibit HOA's from setting rules against solar tech & installation. Here's one interesting case from FL.

[www.ccfj.net]

mrsteve007

heroineworshipper

hoofdpijn

But that is assuming full sunlight 24 hours per day. This is hard to achieve even in San Diego.

Slartibartfast

You make some great points, especially on the pros/con of 'eco-tech.'

Maybe some of my experience can give you a handle on tangible and economic benefits solar power can be for business & personal use. Last year, my company decided to cut our electric use by 50% before the year end of 2008. I'm in charge of this effort. Since we're a market leading architectural firm, and we have engineers, architects & contractors at hand, we wanted to go with some of the most advanced technologies and ideas out there.

I detail our expansion at our website: [www.jbdg.com]

In combination with a 'first of it's kind on the market' HVAC improvement, office efficiency improvements, and a 10kw solar array with 4900 amp hour battery backup, we may even surpass our 50% goals this summer.

For us as a company, we're using our facilities as a sort of technology sandbox, to demonstrate new products to our clients and show that they have a good ROI and ease of maintenance. In terms of client interest, our $93k investment into solar has already paid back.

Since we have relatively frequent power outages that last several days at a time, our battery backup capabilities have already more than paid themselves off in our being able to sustain productivity of our architects. (We lose well over $50k a day in revenue during power outages. Last year, we had an 8 day outage in within Seattle's city limits.)

All of that not withstanding, the simple ROI for our solar project, with battery backup, is 7-10 years. Depending on situations and outside factors, like ours, true ROI can be within months.

mrsteve007

sonicwind

I think this is a good tech idea. We also need to consider manufacturing energy compared to regular tiles and factor that into the equation if you want to talk about being good for the environment.

If these tiles last longer than conventional roof tiles there is the added bonus of not retiling your roof as often. Although I foresee cutting back trees to aid in sunshine on the tiles and less build up of leaves. I do like that there isn't a panel and a roof underneath so its less waste.

delithic

I think N@tedog makes some good points. Look, a financial loss is just that: a financial loss. Any person with any degree of common sense will balance the financial loss against the benefit. If you want to see *massive* market shift to eco-friendly products, you *have* to make the product either financially neutral or financially beneficial. Relying on concepts of massive altruism has never worked in the past and is not likely to work now.

So, when I see something like this, I have to think "how much is going to cost me" and "how much does it help"? If the answer are, respectively, "a little" and "a lot" then my answer is "no thanks."

Look at CF bulbs. Pro: eco-friendly, long term lower cost of operation. Cons: higher investment cost, hassle to throw away. However, I know over the course of the life of the product I will get a positive return on my investment *and* will help the environment, and all I have to do is suck the the initial cost and deal with proper disposal.

I think it's great that there are people willing to sustain potential losses to buy products that are eco-friendly. By doing so, they allow for testing and inject capital into the eco-friendly market. But, I'm not about to drop $18k on a roof unless someone can dispositively show me that I'm not just pissing the money away.

makanai

System Size: 3.0 kW or 3000 Watts
Cost/Watt Installed $8.5

Assumed Installed Cost:
Total Cost $25,500
Rebates & Tax Credits $8,000
Net Installed Cost $17,500

Savings & Benefits*:
Increased Property Value $15,000
First Year Savings $1,260
Avg Annual Savings $2,120
ROI %500
Payback** 5 years
CO2 saved 94 tons (or 188,000 auto miles)

mrsteve007:
I'm guessing they included the routine home maintance cost/benefit of replacing your roof under the "Increased Property Value" header.

The site also "SRS roofs cost, look, last, and install like traditional premium roofing."

Kind of an RTFM for all of us eh?

5yrs... if they speak the truth that aint half bad.

N@tedog

1) @mrsteve007: As mentioned, if this is part of new construction or replacement of a roof, you're getting two in one. What's the cost of a Roof? Now, the incremental cost of having solar is your cost. You'll lose some of that in additional maintenance costs, but still significant.

2) Most solar setups last 30 years or so, so the ROI is there, probably even in cloudly/less sunny areas.

3) There's the intangible value of less pollution, saving the earth, etc. This has no hard dollar value, but the warm fuzzy we get like when we donate to charity.

4) Given that much of our energy is generated by coal, oil, and other non-renewable sources, energy costs will likely rise faster than inflation, so its a bit of an insurance policy against increased energy costs.

Note to the Limbaugh/Fox News fans, you get much more energy out of solar system than the energy it costs to make. Manufacturing, design, and efficiency rates have risen and the energy ROI (cost to produce energy used in manfuacture) is much lower and often lower than the cost ROI.

ARP

Isnt that something.

theconqueror

syphon430

baltwade

Nearly all solar panels have a life expectancy of at least 30 years. Many have warranties that last that long. While it's an assumption, I believe this solar roofing material carries this same warranty. If you're re-roofing to start out with, the purchase of this product covers two separate uses.

Accounting wise, I'd separate the cost of a conventional new roof from the purchase price to calculate the ROI on the solar aspect of the product. In a business, that'd be considered improvement/maintenance of existing capital.

With that in mind, the increase in price for a roofing product that includes electrical generation, it'll pay back in less time, ~5 years.

mrsteve007

N@tedog

I agree with you that this is a terrific invention/inovation but let's just throw in roof maintenance also. By the time you get to Net $0 you have to retile your roof and that's assuming that these tiles have the same avg 10yr lifespan of tar tiles which I'm guessing they don't. I'm also looking at this as if today were time-zero. I agree that in time this could be all you see on rooftops in Arizona, but right here, right now I would have to imagine that this particular product would cost more energy to produce and use than it would save.

N@tedog

Energy is just going to rise in price.

thedarkhorse

imTheKing

imTheKing

@Maksimir: look at your utility bill. It should show you monthly kilowatt use. Appliances like AC and Refridgerators consume alot. But if you add wind power, solar, and add (battery) storage along with the inverters, it helps.

Yes folks, ROI (return on investment) is almost pathetic until you look at cost increase and term of residence. There is also resale to consider (5-10 yrs from now, solar will be more efficient and cheaper. And a market to convert old to new will be viable).

SigmundTheSeaMonster

[michaelbluejay.com]

In IL you save $2k a year assuming it utilizes all 3kW 24hrs/day, 7 days/wk, 52 wks/yr.

So, I stand corrected.. slightly.. At 100% efficiency it'll take almost ONE decade to recoup the cost. Not several decades.

N@tedog

clarkjw

The basic idea behind such systems is that they a) feed energy into a battery from which you can draw when you need. or b) you supply the power you generate into the local power grid and this is the substracted from your actual usage.

And dont forget that such systems are expensive today but will be a lot cheaper tomorow ... so all in all the idea is good and it will get better with time.

Redwraithvienna

baltwade

Stang70Fastback

imTheKing

imTheKing

N@tedog

Maksimir

Curves