Off Topic - Solar Power Cost Savings Through One Block ...


Discussion Topic

Return to Forum List
This thread has been locked
Messages 21 - 40 of total 58 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
Chris McNamara

SuperTopo staff member
Topic Author's Reply - Oct 12, 2008 - 02:05am PT
according to the American Society of Mechanical Engineers:

the energy returned on energy invested (EROEI) for solar is in the range of 10 to 30. They thus generate enough energy over their lifetimes to reproduce themselves many times (6-31 reproductions, the EROEI is a bit lower) depending on what type of material, balance of system (or BOS), and the geographic location of the system.

you can read more here

I have heard anecdotally that the EROEI of solar has doubled every 5 years for the last 25 years. That report was in 2002. i imagine that EROEI has gone way up since then.

are there other engineering or science papers out that that contradict this?

Trad climber
So. Cal.
Oct 12, 2008 - 02:10am PT
The little solar yard-lights I got this year kick ass over the ones from just a couple years ago. And they were cheaper.

Oct 12, 2008 - 02:14am PT
Thanks for the information Chris.

Trad climber
the south
Oct 12, 2008 - 02:39am PT
Mechanical engineers?

Wonder what the ELECTRICAL Engineers have to say about that?
Karl Baba

Trad climber
Yosemite, Ca
Oct 12, 2008 - 10:23am PT
Yeah, Like the war will pay for itself in 100 years. Did the moon shot pay for itself?

New energy technology is critical for this planet. If it costs too much now, spending that money will support the developing tech and lead to eventual economies of scales.



Oct 12, 2008 - 10:31am PT
"Mechanical engineers?

Wonder what the ELECTRICAL Engineers have to say about that? "

The job description of a mechanical engineer is transferal of power from one system to another. We're the ones designing and running your generating plants.
And the materials engineers working on new PV cell design? Bingo, MEs.
Really though, it's a cross-discipline field.

And Chaz,
If you're worried about the efficiencies of PV cells, go passive solar; it's simple and cheap.
Jeremy Handren

Oct 12, 2008 - 10:37am PT
Worth mentioning that the price of panels is going to drop next year.
Large increases in polysilicon supply will be starting to hit the market by the end of the year. Manufacturers have been ramping up volume to the extent that analysts are expecting a glut of panels over the next couple of years. This coming at a time when demand could take a big hit, since the cost and availability of credit is central to the economic viability of PV systems, both big and small.

Karl Baba

Trad climber
Yosemite, Ca
Oct 12, 2008 - 10:41am PT
"I have heard anecdotally that the EROEI of solar has doubled every 5 years for the last 25 years. That report was in 2002. i imagine that EROEI has gone way up since then. "

You have to wonder how good solar would be now if it had received the billions in subsidies that Nuke got over the years



Oct 12, 2008 - 10:49am PT

Good for you. I've been thinking about/trying to budget for solar for a year or so now.

Quick question:
How do you get the 3kw system for 6000 (even post rebate)? One of the sites you linked us to (; suggests that a 3kw system in SF would run more like $26,000 (before rebates).


Social climber
Whitefish Montana
Oct 12, 2008 - 11:32am PT
The crazy part about all this discussion is that everyone is talking about solar panels. There are many new solar technologies out there that could make solar panels a thing of the past and allow houses that are not perfect to benefit from solar technology.

Just one technology is the Solar tube that collects light in a 360 degree environment. An interesting site is and an interesting article is

Just thought that I would throw this out there to chew on.

Engineer by training

Trad climber
The state of confusion
Oct 12, 2008 - 12:16pm PT
I had a 1.76 KV array installed a couple of years ago and
I couldn't be happier. With the Excel Energy rebate and my
federal tax credit, I paid about $7k for the entire setup.
And aside from nighttime, I generate all of my electricity.
I am hooked into the grid, and sell my power back to the
utility, which additionally subtracts from the cost.
A great deal, and it's clean!!!! (When I use power from the
grid I'm using power generated by windmills too)!
I hope you can get your block to do it Chris! Way to go!
Chris McNamara

SuperTopo staff member
Topic Author's Reply - Oct 12, 2008 - 01:10pm PT
Nice work, steve W

here is how you would get a crazy cheap set up in san francisco:

IF you have a good site

3 KW system

$27,000 List Price ($9/watt) Pre-Rebate
-8100 Federal ITC
-5700 Cal. Solar Initiative ($1.90/W)
-6000 SF Solar Initiative Program

$7200 Market Price

If you also join the 1Bog solar collective you save - $1.50/watt so that total cast would be...


If you dont live in san francisco, but live in CA, or NV or another state that gives a rebate of $1.90/W the cost would be $9200

you you save about $1200 a year on electricty. Assuming the historical annual rate increase of 5.5% a year, its pays back 6.5 years after installation

if you finance the system at 6% interest only you pay $46 per month while saving $100 in electricity

here is a chart that helps calculate the cost savings of rebates HOWEVER you need to update the fact that the Federal Tax Credit has increased from a cap of $2000 to 30%

i don't think anyone knows for sure how much installing solar increases the value of your home. but its something.
Karl Baba

Trad climber
Yosemite, Ca
Oct 12, 2008 - 01:55pm PT
Chris, you rock.

Nothing could be more patriotic nor protect you better for the future than supporting alternative energy companies with money (even gov money) and becoming more energy independent yourself



Oct 12, 2008 - 03:00pm PT

Thanks for the saving calculator.

I'd really like to go solar for philosophical and environmental reasons; but the cost calculation has kept be focused on other ways to 'green."

Our electrical bills are on the order of $25-$40 a month, generally toward the lower end of that spectrum (with 4 people in my family). I guess we don't have as many electrical gadgets as other folks or something. The payback period for that kind of savings is long (12+ years). Especially because my current understanding is that CA will not buy back excess power from home systems, so any energy you generate over what you use goes back to the state, but you don't get paid for it.

I'm still interested in working out a good solar system. Here in southern CA I should be a prime candidate for solar. I just have to get someone over here to give an estimate, price the system and rebates, etc.

Thanks again for getting folks interested in this.

Mighty Hiker

Social climber
Vancouver, B.C.
Oct 12, 2008 - 03:12pm PT
The biggest energy savings, as always, are from conserving. That is, modest sized houses built with energy conservation in mind, both in terms of materials and construction, and actual operation. In urban areas, at least, with reasonable density, to support functional public transit etc.

It's a bit like sidewalks - it costs virtually nothing when building them to provide for wheelchair/scooter ramps at corners. It costs a lot to retrofit them.

Recognizing that south Lake Tahoe probably will never have very high density, that houses there are probably fairly large and spread out, and not built with energy conservation in mind.

Good to see that Chris is taking the initiative on this, though, as every bit helps. And a willingness to try new things is essential in terms of the problems facing the U.S., whether energy or otherwise.

Social climber
A prison of my own creation
Oct 12, 2008 - 03:43pm PT
3.2 kW system on my roof. southwest exposure. The shade is not a problem because my dickwad neighbor poisoned my shade tree a couple years before I had solar put in.

I have to wash the panels at least 2-3 times per year or I take a big hit on production. Been running the system for 3 years now. No real issues.
Chris McNamara

SuperTopo staff member
Topic Author's Reply - Oct 12, 2008 - 06:47pm PT
Alright, corey rich is in. Anyone else?

Trad climber
Berkeley, CA
Oct 12, 2008 - 07:26pm PT
Chris, I'm glad you're promoting solar, and looking into it for your own property.

It is true that with the (now uncapped) residential Federal ITC, combined with the CA CSI/NSHP programs, and especially combined with the SF rebate, residential PV is a better deal than ever.

Commercial PV is often an even better deal, depending on rate schedules and patterns of site electrical usage.

This thread has some good information (mostly from Chris) and some common misconceptions (lifecycle energy analysis, E/W orientation "not good" or "not eligible for rebates", 100 year payback, "better to wait for next generation technology", etc).

The reality is that there are only a few choices for truly renewable energy available today, and for many home and business owners, PV makes a lot of sense, both environmentally and financially.

I know because the company I've worked at for the last 5+ years has designed and installed going-on 1,000 real-life, working systems, both solar electric (PV) and solar thermal ("hot water"). As a few posters on this thread have confirmed, there are many happy solar system owners available to share their success stories.

Chris, if you or any other climbers reading this thread can use any help understanding the technical details of PV for your building (electrical, structural, mechanical, environmental), or evaluating proposals from (the huge number of) installation contractors, feel free to email me.

[company plug: if you're relatively local to the SF Bay Area, we are also available to provide a free estimate for your solar project]

Go Solar!


Blake W. Gleason, P.E.
Engineering Department Manager
Sun Light and Power
1035 Folger Avenue
Berkeley, CA 94710
Office: 510-845-2997
Fax: 510-845-1133

Trad climber
The state of confusion
Oct 13, 2008 - 09:01am PT
I've heard there are moves in places where the expense of
the solar systems would be wound into the house's value,
so if the owner sold the house, the buy would be paying
a pro-rated amount for the solar installation. That would be
a super way to energize this market too--the owner, unless they
lived their life out at the home, would get some additional
financial incentive to purchase one.

(On my way to Facelift, my friend Bob drove us by a huge
solar installation north of Crestline, CA).

Trad climber
the south
Oct 13, 2008 - 09:29am PT
God help ups in MEs are doing all the work on solar ( sorry for a little Math/physics/EE joke)

And not everyone is talking about panels.

THE thin film revolution is about to hit big.

BTW, isn't one of Obama's proposals a 35% credit for going solar?

Ant any rate ( haha a joke) thanks CHris fro posting the details of your investment.

ANd yes Karrl, as you know, the moon program paid for itself oer and over, with things line miniturization VLSI and all its much smaller reltaives came from that) and latex paint for example.

IF The idiot rethuglican icon Ronald Rayguns had not dismantled Carters's energy commission, we'd be 30 years ahead of where we are now. THE USA would likely be the world leader in alt energy, and THAT would be GOOD for everyone. Well except oil companies and oil men.
Messages 21 - 40 of total 58 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
Return to Forum List
Our Guidebooks
Check 'em out!
SuperTopo Guidebooks

Try a free sample topo!

SuperTopo on the Web

Recent Route Beta