I've never used PV's. I see big name companies like Siemens, BP, etc. Does anyone have practical experience with these. Is one manufacturer's product considered preeminent?

I would be using PV's in 90+ degrees Fahrenheit during the summer. Also, do any of the top makers make a panel that can be subjected to partial shading? (I understand that partial shading is very bad because current will flow to the shaded cells instead of the battery/load and damage the cell.)

I saw the Real Goods catalog has a panel specifically designed for partial shading in that has tiny diodes at each individual cell, but I was not familiar with the maker.

Finally, should I buy commercial mounting frames if I intend to put a two-panel array on the roof. My handyman skills are nothing to brag about.

-- Puddintame (dit@dot.com), March 18, 1999

Answers

Solarex makes some of the finest panels in the industry, along with one of the longest warranties, 20 years.

-- MarktheFart (quke@ix.netcom.com), March 18, 1999.

I've used Siemens (formerly ARCO) panels exclusively for over fifteen years now, PT. I initially chose them because at the time they were the preeminent supplier of remote industrial systems, and their products could withstand extreme weather conditions like hail and wind much better than their competitors. They're still as good, if not better, than they ever were, but a few other manufacturers now make panels that are at least as good. Solarex is a popular brand... I know folks who have had excellent luck with them, and they're supposedly even a little heavier built than the Siemens panels.

Partial shading is tolerated somewhat by the amporphous panels, but not by the crystalline ones - see my caveat below on amorphous panels. Shading won't damage the cell unless you've got a HUGE array. Te diodes in the panel you saw were Schottky-barrier types, but even they degrade the panel's performance - I personally stay away from such arrangements.

A two-panel array rack can be built up easily with 1" square aluminum tubing and carriage bolts, and some angle iron for the feet - strictly a hacksaw-and-drill job, and you can save a LOT of money by DYI.

Steer clear of the so-called "amorphous silicon" panels. Instead of using single- or multi-crystalline cells like Siemens or Solarex respectively, these are manufactured with a process that more-or-less sprays the doped silicone onto a glass substrate. Initially cheaper than crystalline cells, but power output is also lower, and can drop up to 50% over the first year, after which it stabilizes. The crystalline cells retain their characteristics for at least 25 years with no significant degradation (both Siemens and Solarex offer 20-year warranties on their panels).

My recommendations:

Siemens SM55 - 53w, 3A @ 17v, cost about $355 each, or

Solarex MSX53 - 53w, 3.17A @ 16.7v, cost about $315 each.

Backwoods Solar Electric is a good firm, fine people - I've done business with them for many years and can recommend them highly. Call them at (208) 263-4290. They had both panels in stock a month or so ago when I was pricing out a system for a GI friend and fellow ham.

Hope this helps.

-- sparks (wireless@home.com), March 18, 1999.

Sparks

I bought two of the exact Solarex panels you described. I got them for $300 - don't want to spam, but the company was very nice to deal with, and helpful. If anyone is interested in the source, email me.

I haven't assembled and tested my system yet, but the power industry isn't the only ones planning a drill for April 9...lol. What I can say about them, is that they seem very sturdy and well constructed. I'm looking forward to my drill.

-- Online2Much (ready_for_y2k@mindspring.com), March 18, 1999.

A friend has those panels, loves 'em too... nice and heavy-duty

BTW, I didn't think that posting the phone number of a reliable source of a product was spam... I have no financial interest in the company, just passing along a good source. Personally, I see nothing wrong with posting contact info for such a source when it's germaine to the thread.

-- sparks (wireless@home.com), March 18, 1999.

Crap.

sorry Sparks, I didn't mean to turn this into a "who to buy from" deal. I was reading your post, got near the bottom, and thought, "hey, those are the same panels I bought!" I didn't even read the last paragraph before I posted.

-- Online2Much (ready_for_y2k@mindspring.com), March 18, 1999.

Sparks, Online2much,

Thanks so much for the info. It's not spamming to share valuable information for us. I think your posts falls in the category of "Recommendations".

Thanks again

-- Texan (solarpanelclueless@ranch.com), March 18, 1999.

No problem, Online, really. I just wasn't sure what the forum community policy was on spam... thought maybe I'd overstepped. Some forums are *real* strict on this issue, and I know that some "advertisers" have been taken to task here.

BTW, what kind of controller do you have for that system, and what batteries are you going to use? Six amps should be plenty for lights, etc.

-- sparks (wireless@home.com), March 18, 1999.

Sparks

we made those last two posts simultaneously - if I had seen you had recommended a vendor, I would have *never* made the spam comment, and wasn't acusing you of it.

I HATE it when I'm stupid!

I was going to be posting a couple of questions before setting up my system, but before I do, do you know any good sites for solar information? I need to figure out a wiring system, load estimates tec.

-- Online2Much (ready_for_y2k@mindspring.com), March 18, 1999.

I have a Solsum 5.0X and an identical backup (they were cheap, and it's only money...lol). I have 2 marine deep cycle trolling batteries - 115 amp hours. I have seen the advice to not let them discharge below 50%, but am not sure the best way to determine what level they are at. Any suggestions?

-- Online2Much (ready_for_y2k@mindspring.com), March 18, 1999.

{{ Steer clear of the so-called "amorphous silicon" panels. Instead of using single- or multi-crystalline cells like Siemens or Solarex respectively, these are manufactured with a process that more-or-less sprays the doped silicone onto a glass substrate. Initially cheaper than crystalline cells, but power output is also lower, and can drop up to 50% over the first year, after which it stabilizes. }}

Sparks: Interesting. I was looking at this type because of its apparent ruggedness (flexibity, no glass) and tolerance for shade as well as high temperature, but maybe it's not such a good idea. Do you mean that it stabilizes up to its original rated capacity or stabilizes at the lower (-50% or whatever) capacity that it drops to?

-- Debbie (dbspence@usa.net), March 18, 1999.

Just to clarify, Sparks, do you mean the crystalline type is okay with partial shade except with a huge array? Excuse my density.

I think we all agree it ain't spam to recommend products, that's one thing I look for on this forum.

-- Shimrod (shimrod@lycosmail.com), March 18, 1999.

Here's a few links to solar info and sales:

Home Power Magazine

Backwoods Solar Electric

Real Goods

I've dealt with all these folks at one time or another, and they deliver as promised in my experience.

Online, the two 115 A/h cells should work out fine with a pair of panels, but I wouldn't let the batteries drop below 25% of capacity, which means you could use about 55 A/h before you'd have to start replenishing. Best way to determine state of charge is with a hygrometer, which is a little glass tube with balls in it - you take a little electrolyte out of the cells and see where the balls float in it... basically you're determining the specific gravity of the solution, which is proportional to the state of charge. You can get one cheaply at any auto parts store. There's another method using voltage readings, but it requires a digital voltmeter - I'll post that method if anyone's interested.

Where you place your panels will have a bearing on where the batteries go as far as wiring is concerned. You're working with low voltages and high current, so heavy gauge wire (#8 or better) from the panels to the batteries is a must. Fuses are essential, as well as disconnects when working on the system. Low voltage, but current can hurt you too - drop a wrench across the battery terminals and you'll know what I mean!

Debbie, those flexible panels are just the thing for hiking and kayaking, but they're not too good otherwise. Usually the silicon material is laminated to glass, or in the case of the panels you describe, a type of tough plastic. These types of panels will lose up to 50% of their initial capacity in the first year, and then *usually* stay at that level from then on... so if the panel is rated at 2 amps, a year later, after aging, it'll output will drop to considerably less than that, perhaps as low as 1 amp. They are rugged, but they're still prone to damage as they have no solid frame or tempered glass to protect them.

Shimrod, partial shade will cause some of the array's current to attempt to go through the shaded cells, and this can cause some heating, but you'd need a really large array, say a dozen or so panels hooked together in one set, to notice this effect. If those panels are arranged in parallel groups, say four groups of three panels each, any shaded cells will have to sink comparatively little current, and will stay relatively cool - way below the temperature needed to fry the junction or melt insulation.

-- sparks (wireless@home.com), March 18, 1999.

Sparks,

Question: For a small set-up like we're talking about, is a meter like an E-meter or some cheaper variation necessary, or can you deal with everything by the seat of the pants and the hygrometer?

Comment: Some books of interest "The 12-Volt Bible for Boats" by Miner Brotherton. I've seen this book at several baoting supply stores on the southeast coast. Got mine from Outer Banks Outfitters. This is like a primer on the care and feeding of lead- acid batteries. Will have some extraneous info. on stuff like sacrificial anodes, etc.

"The Solar Living Source Book" by Real Goods. This is a combination catalog/encyclopedia of PV cells, windmills, inverters, charge controllers, etc,etc,etc. About $30 but available in a lot of libraries. Can also be perused at Barnes&Noble. My copy is Ninth Edition. This book itself has a section on books. A list:

Practical Photovoltaics electricity From Solar Cells $19 RV'ers Guide To Solar Battery Charging $13 PV/Generator Hybrid System For Your PV Home $8 Solar Worksheet Design Software $15 The New Solar Electric Home $19 The Solar Electric House $19 Living on 12 Volts With Ample Power$25 The Solar Independent Home Book $17

Notice for Tarheels: NC State University has a solar demonstration home immediately behind (south) of the McKimmon Center on Western Blvd. You can go there and see various set-ups with panels, controllers, batteries, etc. They also have a library devoted solely to solar titles along with catalogs of major manufacturers and retailers. You can also speak with specialists who can tell you some go hard info about mounting angles, production expectations, etc. for this part of the country.

-- Puddintame (dit@dot.com), March 18, 1999.

You can get by with just the hygrometer if you've got a basic understanding of the system's limitations, and don't exceed them, but I consider a digital voltmeter a necessary survival item, well worht the cost. A decent one can be had for $50 or so, with resistance and ampere ranges included (make sure it has at least a 10-amp DC range). It will let you check the current draw of your appliances (important for figuring out how much energy you'll be taking out of the batteries), adjust and determine your solar array's output, check fuses, determine the battery's state of charge... you get the idea.

Let's say you've got a 12v lamp, and you want to run it for five hours per night. Without knowing how much energy it uses, you aren't sure how much needs to be replaced back into the battery bank. Measuring the current with your meter shows a drain of 2 amps, which is equivalent to saying 2 amps per hour for our purposes. 5 hours X 2 amps = 10 amp/hours. Your two panels produce about six amps in full sun, and depending upon where you live and what your annual cloud cover is, you can figure on the average sun-hours as being around four, five if you live in the sunny southwest. 4 hours full sun X 6 amps = 24 amp/hours per day that you have to play around with (since it takes a little more energy to fully charge the battery than was taken out, figure on 20 amp/hours per day in our example). You've used up about half of your daily renewable energy running the lamp, so now what else do you want to run off the batteries? Measuring the current drain of your small 12v NiCad battery charger, you find it draws much less than the lamp - only about 1/4 of an amp. However, since it takes 16 hours to charge the AA cells you put in it, multiply 1/4 amp X 16 hours to find the amp/hour drain, which in this case comes out to 4 amp/hours. That leaves you with about 5 amp/hours to go, but you can't figure on using them all every day, since you may have periods of low or no sun for many days in a row. You probably won't be charging NiCad's every day, so you can use the 4 amp/hours you'd have used on them and put it towards other uses. You could run another lamp for a couple hours per night, but if you got a more efficient lamp, for example the 12vdc compact fluorescants that Real goods offer, you could run both lamps for six hours per night on the energy it took to run the one conventional bulb for five! A 9-watt CF bulb and ballast draws about 8/10's of an amp, making 1.6 amps per pair... and a 9.6 amp/hour drain for six hours use. More expensive than a filament-type bulb, but much more efficient. Such a bulb/ballast combination costs about $40, but lasts upwards of 6000 hours and is much cheaper than adding another solar panel.

I realizeI got a littel verbose with that answer, but I wanted to be thorough :)

-- sparks (wireless@home.com), March 18, 1999.

Hit Home Power magazine's website at http://www.homepower.com/ for an E-mag (Adobe Acrobat's PDF format, so check your Acrobat reader...) on renewable-energy power systems for home use. The print version is a paid subscription but they have the PDF they derive the print from available as a free download.

They have huge numbers of ads for PV, etc. suppliers sprinkled throughout. It's a start if you're looking for info. They also have links to suppliers, etc. on their website.

OddOne, who is debating mixing a PV-based system with a large number of white-LED lighting projects to see if he can drop his power usage down a bit...

-- OddOne (mocklamer@geocities.com), March 19, 1999.

Just bought a couple of solec SQ80 Modules for $724.00.

Thought this was a good deal after checking around.

J

-- j (notnow@yoyodyne.com), March 19, 1999.

United Solar Systems Corp. is an American joint venture solar cell manufacturing company based in Troy, MI. The company was formed in 1990 by Energy Conversion Devices, Inc., and Canon Inc. United Solar's unique thin-film solar cell technology achieves unprecendented levels of efficiency for amorphous silicon solar cells through the use of proprietary triple-junction spectrum-splitting cell design. Its advanced roll-to-roll manufacturing process uses a flexible stainless steel substrate that enables low-cost production and the development of many types of light-weight, robust, flexible and rigid solar cell modules.

United Solar's panels in the news:

United Solar Systems Corp. and Detroit Edison Form Partnership to Install and Fund Solar Roof Array for Detroit's Cass Technical High School

United Solar Products Pass Extensive Qualification Testing, (UL-1703, IEEE-1262, IEC 1646, CEC 701), 20 Year Performance Warranty Now Standard

United Solar Photovoltaic Modules Successfully Installed on MIR Space Station

United Solar Standard Rigid PV Modules used by Genernal Motors for the EV-1 independent charging stations in California

All United Solar products are based on a sophisticated multi-layer amorphous silicon thin-film solar cell developed originally by Energy Conversion Devices, Inc. This spectrum-splitting cell is constructed of three separate p-i-n type, amorphous semiconductor solar sub-cells, each with a different spectral response characteristic. In this way, the cell can convert the different visible and near infrared wavelengths of sunlight with optimal efficiency. The United Solar spectrum-splitting multijunction design now holds all the world's records for amorphous silicon solar cell efficiency, including the highest stable efficiency measured by the National Renewable Energy Laboratory (NREL) for a small-area amorphous silicon solar cell -- 13 percent.

For more info on Uni-Solar products see:

http://www.ovonic.com/unisolar.html

They do not sell directly to individuals, but Golden Gensis Company retails their products. The pricing is very attractive. Or to say, the bang wattage for the buck. A US-21 PV module for $124 and a Sunsaver 6.5 amp carge controller for $42.

http://www.goldengenesis.com/

The pricing on their web page does not reflect what the selling price is.

-- Joe Martin (no_spam@nospam.com), June 09, 1999.