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Old 17-10-2006, 17:01   #1

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The real cost of solar power?

I was wondering about this and surprised I couldn't find any hard numbers on the web. When there's no alternative, or no good alternative, sure, solar can make sense because it may be the only power source. But still...has anyone figured out what it costs them per kilowat hour?

In a less than optimal place, like New England of the MidAtlantic States, counting grey days and winter days, I'm thinking that a solar panel may provide full rated output for really some small number like an average of 5 hours per day, averaging in all the short winter days and overcast ones alike.

With prices like $900 for a nominal 175 watt panel (which really seems to mean 7.5A@14.4V, or 108 watts effective output to a nominal 12V system) that translates in $900 up front for 197 kilowatt hours per year. Which would cost $40-45 if bought from an "expensive" utility company at 22c/kwh. Essentially, the same $900 left in an investment at 5% could pay for the same amount of power ($45) and unlike solar panels, which may be shot after 20 years, the $900 would at least still be there.<G>

The $900 compounded out over 20 years might be worth $2000, making the "real" net cost of the solar power close to 50c/kwh.

Which got me to wondering...has anyone done similar numbers to see the real cost of genset power? Solar? What the options REALLY cost per kilowatt hour when all is said and done?

(And yes, I'm not considering the changing rebate or tax credit incentives sometimes available for solar, I'm just looking at the base price.)

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Old 17-10-2006, 19:12   #2
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I would prefer to buy the power, but the wire from Florida to my boat at anchor in the Exumas would be very expensive!

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Old 17-10-2006, 19:12   #3
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Seems like you did the research. You still need a voltage regulator and a battery bank to store the power you make. The harder part is how much of the power you make is wasted because you didn't need it?
Cost per KW is maybe a false evaluation. I don't see the issue with computing the cost of other forms of power. But you need to equalize the various forms.

Gensets generate a lot of power instanatly for a short period. Solar works during the day but not always the same rate, wind delivers a lot of power but nothing in the calm. The gear on your primary engine genrates power while you run but not without fuel costs. Then there is the battery bank that stores power til you really need it.

The issue of cost gets even more complicated as in is it better to trash your fridge and get one that saves 25% more power so you can eliminate the solar panel you were going to buy to feed the old fridge? Is the cost of power not also linked to the cost of consuming it as well? All your gadgets that you add suddenly need more power.
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Old 17-10-2006, 19:24   #4
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In many spreadsheets there lies despair.
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Old 17-10-2006, 19:34   #5
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Originally Posted by CaptainJeff
In many spreadsheets there lies despair.
Amen brother.......
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Old 17-10-2006, 19:57   #6
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A thing doesn't have to be cheap to be the best available option.

Your climate is a variable factor, your electrical use is another. If you have a euthectic fridge for example, solar isn't as useful. You have to run the motor anyway. I had an electric fridge and I loved the solar because I could leave the boat in the marina or at anchor with out having to run the motor. I also had a wind mill, hated to use it because of the niose but it was handy for those rare times (where I live) when the sun was scarce. In your case I wonder if a wind mill would be the better option? The one I had wasn't a particularly good one and it was a steel boat, thus the noise.

In any case... I'll pay any price for a cold beer!

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Old 17-10-2006, 21:45   #7
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I started doing a cost comparision vers using the motor. The motor cost is fuel, maintance and replacement (number of hours run till the time you have to replace the motor = replacement cost per hour). You will also need to conisider where you will need the solar planels and if there will be sun shine and how much. My cost with the 50 hp outboard is about $ 2 per 144 watts when the motor is not moving the boat. (this may be a little high)

With that cost, it depends on how much amp hours you will be using. LED's, no fridge ect.... all help to reduce the amp hours and you may be able to charge the batteries with regular engin use.

I do not have one but may someday.
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Old 18-10-2006, 04:25   #8
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someone told me that a solar panel will not in its lifetime produce the amount of energy that it took to manufacture it. I wonder if thats true.
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Old 18-10-2006, 04:35   #9
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True. There is no free lunch. It takes more power to make a solar panel than it will ever produce. The advantage is that hopefully it is built with low cost energy and you use it where other sources are unavailable, less reliable, or more costly.

This is one of the things the solar power greenies don't acknowledge. Where will they get all the power to build the panels?

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Old 18-10-2006, 06:25   #10

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We did this comparison and factored in our entire electrical system, usage patterns, and modeled a 5 and 10 year cost analysis.

The result for our use (with 110VAC fridge, northern lattitude, Trojan T105 batts, and TV/DVD and stereo as well as electric razors and the link) was that a genset was the SAME EXACT PRICE!

We factored in oil changes, solar charge controllers, etc...

Our feeling, after analyzing a lot of alternative energy products in general, was that the alternative energy products are priced the way they are so they cost the user the *exact* same amount as conventional energy. After all... the big oil companies say it best: "We are not oil companies, we are *energy* companies." They are going to sell you the solar for the same price as their oil. (BP for one)

To the consumer, the cost of energy is the cost of energy, no matter how you generate it.
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Old 18-10-2006, 06:35   #11
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trying hard to bite my politically minded tongue, I would just say that renewable energy sources set up today will still be producing energy at about the same cost 20 years from now. What will oil be doing 20 years from now?

wont even go into the pollution aspects, but dont you think humans should make choices based not just upon what it costs today?
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Old 18-10-2006, 09:11   #12

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Good points, but I haven't looked at all the options nor gotten back some real numbers (i.e. how many hours CAN you really count on?<G>) that would matter.
I ignore the cost of the regulator and batteries because if you're using stored power at all, some or all of that may already be a sunk cost. And if the max output of the solar panels is less than 10% of the battery bank's capacity, and the voltage not too high...the regulator may even be unnecessary. (May.) It's something to look at--but further down the line. Like the rebates & credits.

"A thing doesn't have to be cheap to be the best available option." Agreed, but I'm looking at the costs here. I want to know the costs in order to consider "best" versus "oops". On the beer...I'm a barbarian, I believe any beer not good enough to be drunk at room temperature (or water temperature) ain't beer. If a fast immersion in a mesh bag won't cool it enough to make it taste good, it's probably Budweiser. UGH.

Yes, fuel, plus incidental use of the main motor or the purchase of a genset...not so easy to figure either, unless you're pricing out the genset path. Or as the credit card commercials haven't said, yet "And the incredible quiet of not running a genset...PRICELESS!" <G>

"not in its lifetime produce the amount of energy that it took to manufacture it." Oh, you mean, like the way the price of a new hybrid car, with the $20,000 someone is paying the manufacturer to make it, and the batteries being consumed in five years, being SO much higher than just sticking gas in the old V8 guzzler and just running it to death?<G> Or the way nuclear power is cheap--until you add in the cost of dealing with the waste products for 50,000 years? Ooopsie.<G>

I had a suspicion it could swing that way.

On what Canibul says about petro prices changing in 20 years...A good spreadsheet accounts for that!
Thirty years ago, on the first US "oil crisis", a geology prof explained to me that geologists had known the problem would be coming since the 50's. They knew the supply and the demand, and where the cross would come--ignoring politicial instabilities and OPEC, which could only make it worse. And, even back then, they knew that Hitler's war machine moved on SYNTHETIC fuels, i.e. gasoline made from coal. The cost of "build" gasoline the hard way was and is predicted to be around $4-5 per gallong. Back when gasoline was 38c that sounded radical. What we're seeing now, is just the final "adjustment" to $4.50/gallon, at which point the US has enough coal to build 400 years worth of gasoline without considering other sources. Get used to it, that's where the price *will* reach before it can be stabilized as a market commodity produced all over the world, instead of sucked from the ground. If something cheaper comes along before then...great, if it happens. The other synfuel projects I've heard from are all using $4-5/gallon as target prices.
I'm all in favor of voluntarily changing sources and paying $5 *now* and telling the Caliphate to go pound sand and starve.
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Old 18-10-2006, 09:30   #13
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man, now THATS political...
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Old 18-10-2006, 12:02   #14
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You are right, the alternate energy systems that are so loved by the Greenies just don't add up economically. Lived in our house with solar/generator power for more than 10 years. Expense of PV panels to come anywhere close to our needs would have been way over $20,000. We gave up at $10,000 and bought a better generator. It's not that we had excessive electrical use, everything that could be propane powered like refrigeration, was, and we were fanatical about turning off anything electrical not being used. The problem was the invertor which eats juice at prodigious rates with little relation to output. It was also a source of constant maintenance and loved to crap out at the most inopportune times. Suffice it to say that the solar powered city is nowhere near ready for prime time.

Solar Panel production has gotten way more efficient. Solar panels will now produce enough electricity to cover the energy used in production in less than 5 years. That doesn't say they will pay for their purchase cost, however.

The spent nuclear fuel storage issue is totally a political, not a physical problem. It's all about NIMBY. New reactors don't produce much in the way of long term radiation by products. They can also be designed to reuse 'spent' fuel so they are super efficient, almost perpetual motion. Almost all the long term radioactive by products are about making bombs, not electricity. Former nuclear weapons facilities like Hanford, WA are relics of the Cold War that do have major problems. They are not problems because of nuclear power production, however. If we are going to ever have Hydrogen powered vehicles, with our current technological level, Nuclear power is the only power source economically feasible to split Hydrogen off of O from water.

Having said the above, I learned to hate generators living on one on land and having the assholes in boats running them 24/7 in a quiet anchorage. I'll be sticking as many panels as I need to meet my needs on my boat. Fortunately, LED's have made the current drain relatively low and refrigeration is a PITA that I can easily live without. I like Brit beer drunk Brit style. It won't take a lot of panels to meet my needs as long as I stay where the sun shines. Since I plan on going north, will have to see if I can stay with strictly solar power but will try. From experience, PV production is pretty abysmal unless you have full sun from 10-2, btw.

To make up the differential in purchase cost of a Hybrid over a regular gas powered vehicle, you need to drive it over 100,000 miles. When's the last time you personally put a 100K on a vehicle?? Interestingly enough, Hondas have the worst pay back specs. It's not because the hybrids are less efficient but their gasoline powered cars are too efficient. Don't know if the payback figures include replacement of the batteries. If it doesn't, hybrids are really not such great deals. Modern diesels are probably way better choices but, unfortunately, nearly impossible to find on this side of the pond.

Peter O.
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Old 18-10-2006, 12:19   #15

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"Modern diesels are probably way better choices but, unfortunately, nearly impossible to find on this side of the pond. " Apparenelty for a couple of good reasons. They need low-sulfur fuel (which has only just been phased in here, partly because the vast base of older engines need the sulfur as a lubricant like lead in leaded gasoline) and they run dirty, with high particulate emissions. Which have led to "global cooling" by significantly blocking sunlight, which in turn may become a crop issue.
Personally, I can't stand the smell of diesel exhaust. I'm waiting for someone to work on that.<G>

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