The expense of Solar Power

[dd74]

Can anyone tell me why solar power is so expensive? I mean, from my uneducated pov, solar power comprises (for the home) a bunch of panels that go atop someone's roof. I'm serious, though. How come solar costs so much for home use?

[9dreizig]

think of it as LOT"S of semiconductors on a plate..

[jyl]

Traditional solar cells are made from polysilicon wafers (currently global capacity is still tight) in a semiconductor-like process (so substantial capital cost for clean room and equipment). Thin-film solar cells are considerably less expensive but also less efficient. The cost curve for both is declining pretty rapidly, in a few years the $/watt of the panels will be substantially lower, partly from higher panel efficiency and manufacturing efficiency, but also because a lot of new polysilicon capacity is coming online in the next 2 years.

[red-beard]

That is only half of the problem. Like with most wind systems, you generate DC. For you to have a serious system, you would need to have a battery system, a static inverter and a "dump" for the times when you produce too much power.

While techincally you can connect the static inverter to your mains in the house, the utilities do not like this. Not so much because you "competing" with them, but mostly because of the danger if the system is not put together correctly. Secondary power feeds are usually what kill linemen.

Texas does allow net metering. But if you produce too much power, beyond your uses, all you get it the cost avoidance rate ($0.04/kwh).

[berettafan]

Interesting post!

This just came up at our last utility commission meeting. There were some folks in attendance (all meetings are public) who were talking about having an electric meter actually run backwards via solar power generated by the homeowner.

Redbeard do you have any cites on the 'secondary power source' issue? I'd like to forward those along if possible.

IR2 solar power in general i seem to recall Wayne describing it as less than efficient. Rough math proviced by one of our 'green' commission members tells me that at BEST you are just shifting utility money from the power company to the solar cell co.

[Jim Richards]

Originally Posted by berettafan

Rough math proviced by one of our 'green' commission members tells me that at BEST you are just shifting utility money from the power company to the solar cell co.

Is one an ongoing charge and the other a one-time charge?

[berettafan]

well you figure your solar system has a svc life of 'x' years. throw in a variable for risk of damage (we get the occasional hurricane and such) and the math just isn't too exciting.

one of the vocal attendees was a salesperson for a solar co. and her schpiel was focused on claims of massive future increases in municipal power costs. i got the feeling that if there were good math to share NOW she'd have done it.

not to mention if it were so efficient our power company would be looking at replacing generators with solar cells as well.

[berettafan]

i will add that NONE of the parties in the discussion (myself, the other member and the saleslady) were experts on solar cell technology.

[jyl]

Home solar systems on the West Coast are usually "grid-tied", meaning they have panels and inverter, tied into home electrical service. When you produce more than you use, the meter indeed runs backwards. If the utility electrical service goes out, these systems are usually designed to shut down, which addresses the safety issue you mentioned.

These systems usually do not have batteries. For most people, there is no reason to have batteries in a home solar system, as power outages are uncommon.

Edit: I said "West Coast" - grid-tied systems may be designed this way most places for all I know, but I've only checked into CA and OR.

Originally Posted by red-beard

That is only half of the problem. Like with most wind systems, you generate DC. For you to have a serious system, you would need to have a battery system, a static inverter and a "dump" for the times when you produce too much power.

While techincally you can connect the static inverter to your mains in the house, the utilities do not like this. Not so much because you "competing" with them, but mostly because of the danger if the system is not put together correctly. Secondary power feeds are usually what kill linemen.

Texas does allow net metering. But if you produce too much power, beyond your uses, all you get it the cost avoidance rate ($0.04/kwh).

[lendaddy]

There are also automatic service disconnects as are used in back-up generator systems. They sense the lack of line power and disconnect. They are however not cheap.

[jyl]

All that being said, I think the large majority of the cost of a home solar PV system is the panels. About $5/watt. "Watt" means rated max watts, which you don't get all of the time due to sun angle, weather, shading, etc.

[john70t]

Solar panels should be getting close to widespread affordability. There are new developments every week it seems.

Some more info and links here:
http://www.gizmag.com/geos-zero-energy-residential-community-launches-in-colora/9647/

[svandamme]

Originally Posted by jyl

Home solar systems on the West Coast are usually "grid-tied", meaning they have panels and inverter, tied into home electrical service. When you produce more than you use, the meter indeed runs backwards. If the utility electrical service goes out, these systems are usually designed to shut down, which addresses the safety issue you mentioned.

works the same here

[JeremyD]

I've been looking at this too - sunny florida makes a good argument - especially to power AC systems. Unfortunately the cost is way up there for the cost benefit. I did design my house with the roof in mind to some day take advantage of this when the cost came down and the efficiency came up. I had the roof designed so you could not see the rear panel area from the street and a large semi protected area at optimal tilt to the sun.

[tcar]

Originally Posted by jyl

All that being said, I think the large majority of the cost of a home solar PV system is the panels. About $5/watt. "Watt" means rated max watts, which you don't get all of the time due to sun angle, weather, shading, etc.

Is that true?

So, $500 for enough panel to power a single 100 watt bulb.

Payback would be, what, 10,000 years?

Good idea, if true.

[Mule]

Another guy with facts now! Geez where is this "reality" place you all live in!

[Aurel]

Originally Posted by tcar

Is that true?

So, $500 for enough panel to power a single 100 watt bulb.

Payback would be, what, 10,000 years?

Good idea, if true.

Now, with the cost down to $1/W, and using white LED lighting that consumes 20W for the same light output as a 100W incandescent, your cost is down to $20.
This illustrates that the solution will come not only from cheaper pannels alone(which polysilicon is very close to now), but their combination with other innovations. The energy problem must be adressed at both ends: production and consumption.

Aurel

[lendaddy]

In my quick search I found sale prices for a 200 watt panel at $1,050(normally $1,900). Considering that those are peak ratings lets assume 75% (I'm sure beyond generous) and 14 hours of sun a day (again beyond generous) and what you have is 2,100 watts for each day. This is enough to power one 85 watt bulb for the day. The electricity would have cost you ~$0.20 from the grid.

So our "investment" should be in the black in about 15 years assuming no performance degradation and free installation.......26 years if we miss the sale

[lendaddy]

Originally Posted by Aurel

Now, with the cost down to $1/W, and using white LED lighting that consumes 20W for the same light output as a 100W incandescent, your cost is down to $20.
This illustrates that the solution will come not only from cheaper pannels alone(which polysilicon is very close to now), but their combination with other innovations. The energy problem must be adressed at both ends: production and consumption.

Aurel

Yes but you can go the LED route with grid power as well so the curve remains unchanged.

[jyl]

My rough calcs, recently updated:

10 year payback
Cost of capital 7%/yr
Utility electricity $/kwH inflation 7%/yr
(Edit: Currently avg rate in Portland is appx $0.10/kwH. Utility is requesting +9% increase this year, after a +6.8% increase last year. I'm assuming +7%/yr inflation in utility electricity rate. Every +% increase in assumed inflation rate adds appx $500 to economically justifiable cost of a home system for me. But, I'm already assuming a significant inflation rate.)
Initially cut my electricity consumption (in kwH) 30%, then hold kwH constant
I can justify an upfront cost of appx $9K for the system, or $15K including current tax incentive ($6K tax credit over 4 years)
(Edit: I'm disregarding current federal tax credit since AFAIK it expires this year. Most likely gets renewed, I'd think, but not going to count it until I see that law passed/signed.)

Assuming no change to tax incentive, I need installed $/watt for the system to decline appx 50% before the project becomes economic.

I haven't dug into it to figure out how long that 50% might take.