Ask MetaFilter questions tagged with solar

More info needed about the world of Thin-Film solar panels

thewalrus — Mon, 05 Oct 2009 23:45:13 -0800

Solar power question: What is the pricing of thin-film solar panels like per watt, compared to standard PV cells? I'm comparing 80W thin-film panels in the 6% efficiency range to 135W, 185W, 210W sized Kyocera panels. Also questions about sourcing from China and thin-film solar manufacturing. I am working on a spreadsheet that calculates the cost of a medium to large sized off grid solar power system.

This is normally based on a standard setup of 135 to 190 or 210W sized Kyocera panels on ground mounts, with MC4 cabling and connectors to junction boxes, with the rest of the setup pretty normal (a lot of 200aH batteries, fat wires, 3000W sine wave inverter, appropriately sized Morningstar charge controller, etc).

I have what I think are the best $ per watt prices for Kyocera or house brand panels from SunElec and a few other USA dealers of solar panels sold by the pallet load. This works out to $2.38 per watt+shipping for their house brand 210W panels or about $2.98 per watt for the more expensive panels, or slightly smaller sizes.

I have followed with interest the news over the past few years about startups like Nanosolar and First Solar claiming to approach the magical $1/watt figure with inexpensive albeit relatively low output thin film panels. If you google "China thin film solar" and look around on Globalsources you will also find several manufactures of thin film panels in China.

The typical large thin film panel appears to be about 1300 x 1100 x 50mm with an output of 70 to 95W, a bit less than half of the output from a similarly sized traditional PV cell. I don't care that the output is less - I care about the $/watt. If it's less, I'll go with thin film.

The problem, and finally the question, is that thin film pricing is more opaque in the marketplace that the highly competitive regular panel market. I can open the websites of eight bookmarked dealers and look at bulk prices for pallet loads of panels easily, but none of them sell thin film. I have seen a lot of PR about the output of many thin film factories going primarily to large (1 megawatt+) grid-feeding solar panel power plants, which is great... But does that mean the average person or small business putting together a more modest solar setup can't get the best pricing? Particularly I'm thinking of costs under $2/watt. Does anyone know what a 80W thin-film panel is supposed to cost, FOB China, or have links to dealers in the USA that sell them?

Reference links:

SunElec, dealer of regular panels

More on China thin-film solar manufacturing and sources

Globalsources.com product listing of thin-film panels made in China, 30W to 90W size range

mini solar chimney for micro power generation

kimyo — Sun, 27 Sep 2009 14:17:51 -0800

i'm fascinated with the solar chimney concept for electric power generation. i'd like to build a small, fabric-based model, see if it might be able to provide enough power to charge a couple of car batteries. does the mefi hivemind want to help me brainstorm? there's some pretty decent video here of a large scale project in australia (not yet constructed).

i'd like to design something which could be built from locally available materials, nothing too complex.

a smallish tethered hot air balloon might serve to support the structure.

a long tapered cylinder made from fabric (fireproof at the bottom) would be suspended from the balloon and anchored to the ground.

at the top of the cylinder we need some kind of turbine. hot air exiting might also feed the balloon. at the base we'd have a small wood fire.

i'd love to hear from any and all mefites, with or without experience in power generation/off grid/ballooning.

if it works, i think we should call it a montgo.

How to long until we hit 1.21 gigawatts?

advicepig — Fri, 18 Sep 2009 08:03:57 -0800

How can we present instantaneous stats on our energy consumption and generation in a site with a windmill and possibly other forms of energy generation? We have a number of sites where we're going to install windmills, solar, and other green bits. We'd like to have the meters attached to these sites continuously report how much energy they are drawing from the grid, putting on the grid, and how much is being generated by each device.

We were using a meter that I'll choose not to slander here. According to spec, we should be able to get this data, but we found its serial modbus connection to be lacking. Ideally, the equipment on site would be internet connected and not rely on a server at the site, but relay data to a central server under our control.

Solar powered Netbook?

The otter lady — Thu, 06 Aug 2009 16:39:29 -0800

Best netbook/solar combo recommendations for keeping a journal while on safari? I've got the chance of a lifetime and I'm going into the Rupununi, in Guyana, South America. Apparently electricity is very iffy. I would really like to keep a journal, and it's easier for me to type than write, so I think I want a small, durable netbook, preferably one that could be recharged with solar power, like one of those solar backpacks or beach totes. I've browsed around the net and I like the Asus EEE Surf 4G, but the Voltaic backpack and Generator chargers aren't compatible with it so I'm back to square one. Any suggestions, oh hivemind?

Four of the clock it was, so I as I guesse

zvs — Wed, 05 Aug 2009 12:57:54 -0800

How can I estimate the time that a photo was taken? I'm working on a rephotography project (the link is my profile website, if you want an idea of what I'm dealing with). I've gotten the hang of many of the common problems I encounter when duplicating photos, but one thing still gets me -- time of day. I try to estimate based on the angle of a shadow, but that usually only gets me within a three hour window, and I hate sitting around waiting for the sun to move.

I'm a good enough geometer that I can usually figure out what the angle of a shadow is relative to true north using Photoshop, a street map, and a protractor. I have the date each photo was taken. I know NYC is about 15 minutes off of true noon for the time zone, and I know the angle varies seasonally. How can I do the math?

Solar power, the Bay Area, and me

the cake is a pie — Sun, 05 Jul 2009 12:54:02 -0800

As we will probably end up buying a house in a sun-drenched corner of the San Francisco Bay Area, I'd like to learn more about solar panels. I'm looking at a traditional photovoltaic, augment-the-grid setup, but feel free to be creative in your recommendations.

What are good solar panel brands? what are brands that I should avoid?

Any particularly good or bad experiences with installers?

Where are the sweet spots in the 3-D graph of wattage / area / cost?

Are there any developments that could change the market significantly in the next few years?

Where can I learn more?

what voltage?

wilful — Wed, 27 May 2009 23:24:16 -0800

12v versus 240v set-up in a new off-grid (solar PV) residence. I'm trying to work out the benefits in a new house of wiring for either 12 volt (the way the juice is coming in from the solar panels and batteries), or 240 volt (Australian standard mains power). What are the pros and cons of one way or the other?

You lose a lot in the inverter (do you??), but kitting out a house with 12 volt appliances is difficult.

Would you pay less for flex for 12v? Would it really be safer (some claim)? You couldn't connect to the grid without an inverter.

Can the sun power my building?

mkultra — Mon, 18 May 2009 11:49:09 -0800

Is solar power feasible yet for a multi-unit dwelling? I live in a 16-unit building in Brooklyn, 4 units per floor. I'm guessing that the square footage of the roof is in the ~2000 - ~2500 sqft. range.

Using current technology, is it possible to install enough solar panels to power the building? If not, is technology heading toward a place where this will become feasible in 5 years? 10?

If it is feasible, what's the back-of-the-envelope estimate on cost? Has anyone done any kind of analysis to determine what kind of cost/revenue structures something like this would entail?

Solar power in space?

greytape — Thu, 16 Apr 2009 13:35:23 -0800

Would orbiting solar power farms be remotely practical? So I've just read this story and it fairly blew my mind; now that's a 21st century solution to the energy crisis. Made me think though. Is this evenly remotely practical? It all seems to make a lot of sense, apart from the disgustingly high cost of putting stuff into orbit.

The most curious part of it for me though was the means of transmitting electricity via radio waves at 90% efficiency. I totally didn't realise this was possible. According to the Guardian article, this is more efficient than using wires to transmit power, wow. If this is true. why don't we have a network of satellites transmitting power around the world? Set up the mother of all solar plants in the Sahara and broadcast the power across the globe.

So really I'm asking about what some of you engineer types think about the story. Does this seem like a genuinely innovative idea, a flashy distraction or a vapourware nonsense proposal?

Thanks,

Ok, so you have hot rocks. Now what?

bitter-girl.com — Tue, 14 Apr 2009 10:56:42 -0800

This weekend, I saw a green renovation show that used a large amount of gravel in the basement to hold heat gathered from a solar-collecting area in the roof. My dad, a builder, says this method doesn't work well. Help me understand if someone has devised a "better mousetrap" or if this is just something that has never worked and is being done for greenwashing on TV... The premise: attic space with solar glass panels in the roof (which are exceptionally clear and transmit the most UV rays through) also features double-insulated windows on the inside wall to let light in. Space heats up, presumably like a big solar cooker, and using a 12" PVC tube + small fan, the heat is transmitted to a large, concrete-block-walled room in the basement filled with a few tons of gravel.

Show host says the heat from the attic space warms the rocks, whose thermal mass then distributes the heat for up to 48 hrs. But HOW?

My dad's a carpenter, and worked for a gravel company in the 70s. He said he's seen this done before but it's not very effective.

Effective/efficient are two different things... presuming the heat makes it down and warms up the rocks, sure, they'll stay warm for a while, but what's making my head hurt is HOW can this heat be used to warm up the rest of the house? Even as an adjunct heat source, it just seems as if you'd have a nice warm roomful of rocks in the basement and not any real effect elsewhere, no?

I'm interested in building a straw bale house with an insulated foundation someday and am wondering if putting a system like this would help warm the area under the first floor, but can't quite wrap my head around how this works, or would work best... thanks!

Your experience and advice re installing solar arrays?

lemonade — Mon, 30 Mar 2009 11:39:19 -0800

Your experience and advice re installing solar arrays? I am considering having solar arrays installed on my roof (in LA area). Have any of you had this done, and have any tips/things I should consider? Also, recommendations for installers welcome.

Solar/ Renewable Energy Research

wts111 — Sun, 01 Mar 2009 18:28:08 -0800

I am looking for research data on demographic trends of customers of companies that have opted to install solar energy systems on their buildings. My hypothesis is that companies who invest in solar will attract a more affluent customer to the desired call to action than companies in the same industry, all other things being equal. I am interested in any data pertaining to manufacturing, retail, medical, commercial office, etc. applications. Any ideas of where I can find any secondary research that has been done on solar (or renewable) energy demographics? Thank you!

Where's the best place in China to see the upcoming solar eclipse?

the duck by the oboe — Tue, 17 Feb 2009 16:37:47 -0800

Where in China should I go to best experience the total solar eclipse this July? I've been thinking about visiting China for a while and the eclipse is just the excuse I need. My plan is to go to Beijing, Shanghai and Guilin but nothing's definite.

This map shows the path of totality for the eclipse. Where along the path is most likely to have clear (enough) skies?

Help me remember the title of a space adventure/combat/exploration PC game from the early 1990s.

greycap — Mon, 12 Jan 2009 10:10:08 -0800

I'm trying to remember the title of a space combat and exploration shareware game for the PC from the early 1990s. I remember playing a space adventure/combat/exploration game in the early 1990s, perhaps around 1993 or 1994. It was on PC and was shareware. The graphics were VGA quality. You controlled a spaceship from a top-down, birdseye perspective. You navigated with a coordinates system, so you'd find out a certain planet would be at (say) coordinates 25, -65. You'd then head over there and do whatever you had to do. At one side of the screen (perhaps both) were some control panels, part of which was a viewscreen that showed you the head of the pilot of any other spaceship you spoke to.

I can’t remember anything about the missions you had to do, but I do remember that the objective of the shareware demo was to achieve some kind of warp capability. You ended up halfway across the galaxy and were greeted by a strange yellowy white alien. Then the shareware demo ended. I never had the full game so I never knew what happened next.

I’ve been racking my brains for the title, does anyone else remember it? If I see a screenshot I will recognise it instantly!

Solar Panels for Free?

matthelm — Fri, 02 Jan 2009 10:23:09 -0800

I heard about a company that installs solar panels and then they take part of the energy created as a source of paying for the panels and installation...does this sound right and does anyone know of such a company?

Solar help: Keep a 12V battery charged?

jldindc — Mon, 08 Dec 2008 12:28:02 -0800

I have some remote monitoring equipment out in the woods that runs on a single 12 volt deep cycle car battery. How do I keep my 12 volt battery charged using a solar panel? I don't know anything about solar panels and such devices. The battery keeps the equipment running for about 15 days (once the voltage drops below about 11, the equipment stops running). Unfortunately, the equipment is in the middle of a forest, with the top of the tree canopy at about 75 feet. In the winter time, the leaves have fallen, so there's a bit more light reaching the ground. The equipment is on the ground. I may have some problem with branches from above breaking, then falling and striking the panel.
What exactly do I need to keep this battery charged, but not over charged, and not allow the battery to discharge a night while the panel is not getting any light?
Thanks for any thoughts, and keep if simple since I'm a complete beginning with solar and electricity issues.

Alternative energy - when, where, how, why?

zaebiz — Wed, 22 Oct 2008 19:31:53 -0800

What would it take of an alternative energy to make a serious impact in current global energy consumption? What cost/benefits would it need to demonstrate over and above existing sources? Who would need to seriously start using it? Anybody have some good sources of information or discussion on this topic?

When do I go solar?

atchafalaya — Tue, 30 Sep 2008 14:42:18 -0800

Is now the time use solar power for my house? Is there some big breakthrough right around the corner I should wait for, or should I stop waiting and get solar power for my home now?

I want a grid-tied system, but mostly so I can still have power after a hurricane.

Power where I am is really cheap, (my bill rarely exceeds $100 a month) so I'm not really in it for the money. On the other hand, Louisiana has a great state-tax incentive program this year, so it would be cheaper to get.

Would it be safe to get it now, and then upgrade with new panels as they come on the market?

Can I fly internationally with a lead acid battery in my carry-on?

mateuslee — Fri, 12 Sep 2008 08:06:49 -0800

In just a couple weeks I will fly to a remote area of Peru from Europe via the US. I'll be bringing some research equipment which including a mobile solar unit. That solar unit is powered by a lead acid battery like this one. Technically, this is an okay thing to bring on carry-on because it is dry-cell (i.e. not like a car battery), and as far as I know it conforms to TSA standards.

However, it is expensive and I know that the TSA aren't exactly known for their willingness to cooperate or their friendliness. This battery is pretty expensive and it would be a shame to lose it.

I wonder, is there some sort of documentation I can bring to show the TSA and other authorities which will demonstrate that I have a legal right to fly with this device and that it is not dangerous or threatening...

If not, and perhaps more importantly, is it safe to put this battery in my normal (non-carry-on) luggage? I don't know about the safety issues involved...

Thanks guys! You're the best.

Can I install solar panels that only send the electricity back to the electric company?

GernBlandston — Wed, 06 Aug 2008 07:57:25 -0800

Can I install/configure solar panels on my roof so that the energy produced goes directly to the electric company as a credit to my account? I'd like to install some panels, but I don't want to invest enough money to power my house exclusively with solor, and I don't want to store the power using the current batteries that are available. Thank you.

I would like to know about the future of solar energy

heylight — Mon, 28 Jul 2008 05:11:25 -0800

I would like to know about the future of solar energy. I want to know about the future potential/possibilities of solar energy over the coming century, and beyond... are there any books (preference) or websites that go over this in detail? Something scientific and thoroughly researched and not just a series of wild speculations.

Any help would be great!

Solar Panels R Fun!

aetg — Thu, 26 Jun 2008 19:09:19 -0800

Do you have this backpack? Have you taken it through the TSA? What about the airports at Paris, Johannesburg, or Dakar?

For obvious reasons I want to use it as my carry-on bag, but I'm concerned that the additional cords and wires might caused it to get searched or seized.

Actually, I'm not so worried about the search as much as the seizing.

Any personal experiences or links to articles welcome. Random speculation would not be helpful in this case. Thanks in advance!

Advice on solar hot water systems in the UK? What do I need to know?

handee — Mon, 23 Jun 2008 01:26:58 -0800

Solar hot water and central heating for dummies? I'm in the UK, our (gas, combi) boiler has been rubbish since we moved in, and given that we're now looking at a new boiler we're thinking of complementing it with some sort of solar panel based solution. What should we look out for? What do we need? Can we reuse our existing radiators? What questions should we ask installation companies? Caveats:

We don't currently have a tank, and we don't have much space for one (loft has been converted).
We need to get it done fast (expect current boiler will not last the month). Recommendations of suppliers to use and/or avoid welcome.

Recommendatinos for installers of PV systems in SoCal?

jaimev — Mon, 25 Feb 2008 09:25:20 -0800

Looking for installer recommendations of grid-connected solar photovoltaic panels in the Southern California Edison area. We had a salesman from a Santa Ana installer company come by over the weekend and gave us the pitch for PV panels. We're interested, but I'd lover to hear from any folks who've actually had panels installed. How was your experience with your installer? Has the benefits of solar power matched the promises that were made to you initially?

DIYWAMH

aetg — Sun, 17 Feb 2008 13:24:21 -0800

Working on DIY solar charger from modified garden power lamps. Of course the panels look different than the ones in the pictures! I am working on modifying those garden solar lights into a solar panel charger like shown in these two DIYS

Of course now that I have the solar panel completely taken off of the lamp it doesn't look anything like the solar panel in the above picture instead it looks like this.

I can see the two edges where the lamp was wired before and I have been soldering the wires to it and trying to run the lamp via the sunlight. No luck so far. I've also tried reversing the wires in case I got the positive and negative parts screwed up. Any suggestions to continue? Do I need different solar panels? Would it be a problem with the solder instead? (the solder did seem rather weak and popped off rather easily)

As you can tell, I don't do wiring for a living. Let me know if I'm missing relevant information in this question (questions relevant to the wiring not why do you want to do this or why don't you just buy a solar panel, etc)