Older BP/Solarex panels

[gwest]

 Hello everyone,

 I'm very new to any type of PV application so bear with me. I aquired four older BP panels from a guy that really didn't know what to do with them. I know they are meant for grid application use. The panels are rated at 42W/117V each and are 28" x 48" and are of the old amorphous silicon design between two panes of glass. Each panel has four leads two hot and two neg. I've been asking two friends by e-mail,one at builditsolar.com (Gary)and another from HomesteadingToday(alternate energy forum) and not getting a lot of needed knowledge. I've been told I need to wire them in series and parallel into a combiner box,to a controller to a battery bank to use an inverter with them. I would be very grateful for any help anyone can give me. As of this time I'm unemployed and don't have a lot of funds to spend on this project. I started this project in hopes of powering my small shop with the panels in some way just to get the feel of using PV panels for alternate power. My experience in the alternate energy field has been limited to heating air and water. Here's some pic's of the panels I have.  







http://www.fieldlines.com/images/scimages/13763/BP_2.jpghttp://www.fieldlines.com/images/scimages/13



763/BP_5.jpg

 I put in one pic of me laying on my back taking a photo through the panel of the sun and a tree in my backyard so you can notice that you can see through the panel. I have e-mailed BP about these panels to no avail and also have learned BP didn't publish any information on this type of panel. I don't have a problem wiring something up as I worked as a residential electrician for a few years but I know working with PV panels and DC voltage is a whole new animal :-)

                                                               gwest

                                                               Cartersville,GA.

[DamonHD]

Hi,

Understand first that 4x42W ie at best about 160W at best, and only when the sun is shining directly on them and you use them optimally from an electrical point of view, is not going to power as much as you might be hoping.

I'd quite like to build a sun porch with them if I had the space, so they get good sun and I get nice shade.  It's all the rage with architects these days I think.

Maybe you should think of a simple MPPT controller (to get the best out of your high-voltage panels) into a 12V battery bank and wire up some 12V LEDs to work by instead of your normal grid-powered lighting: that way you can use your solar power instead of grid when you have it (and save a few pennies) and it's not a disaster when you run out because you can just use your normal lights again.

In my home-office I work by either a 3W LED or a 9W LED or both when really pushing the boat out!  It's been fine for a couple of years or so now.  B^>

I understand that funds are a problem: maybe others here can advise how it might be possible to get a 'cheap' MPPT for ~160W.

If you are prepared to be a human controller then you can parallel up all the panels for maximum current and minimum voltage to waste as little as possible, and carefully connect/disconnect the solar manually directly to the batteries watching to avoid over/under charging the batteries.  Obviously the voltages are high enough to be lethal so treat as if grid I guess.  You might also want to run (say) a 24V system if you can get cheap batteries to get twice as much of the useful power out of the manual system, and still buy relatively cheap accessories such as lighting from an auto/truck store, but without an MPPT/step-down tracker you'll still be throwing most of it away.

Rgds

Damon

[ghurd]

What is the open circuit voltage, in good sun, without any portion of the panel being shaded?

G-

[gwest]

ghurd,

   When I put a panel out in full sun and put a metter across the leads it shows 117 volts, do the same thing in the shade and one panel will read 60 volts. I forgot to mention earlier that these are low amp panels 0.35 amps per panel.

                                                                 gwest

[gwest]

Damon,

  I would like to be able to use the panels to store power with into battery banks wired in series then parallel to boost the amps. I know that I'll need a MTTP controler for the panels and BP used to make one for these panels(can't find them now) I'm going to try and put another photo in here :http://www.fieldlines.com/images/scimages/13763/BP_2.jpg

[ghurd]

I suggest a load test to see what kind of power they can make.

A lot of that type of panel wear out in a strange fashion, such that they can supply rated Vo and Isc, but they can't make anywhere near both at the same time (or the rated power).

Sometimes it shows up as being easier to see through in large random areas of the panel.

Yours looks pretty even, but I would load test them before committing to an expensive controller.

G-

[gwest]

G-

  Here is a qoute from a man "Julian Powell" that used to use 40 of these panels at one time or another:"I have a lot of experience with this particular panel as I lived off the grid for a year using 40 of them.  My peak output was 1.3kW or 30W/panel which corresponds to the 30% degradation that can be expected with amorphous silicon in the first few years of use.  I can help you with an inverter if you like, I modify computer battery backup systems to function as solar inverters.  You should use a 48 V nominal system, your actual working voltage will fluctuate between 50-56V depending on the charge state of your batteries and the solar exposure.

If you are looking for batteries I have a number of 7.2A-Hr 12V batteries - they sell for about $20 new, I can sell them at $30 for 4.  You'll need sets of four to reach 48V.The open circuit voltage is 84, not 117.  Their peak output is at 60V, if you run at as lower voltage the wattage will drop correspondingly. BP used them with an MPPT Inverter that sweeps the voltage and optimizes it based on current conditions.  I had some of those inverters and sold them already but they are grid-tie, they won't work w/o 220V present."

 That is pretty much all the info I could get out of Julian, he runs zentech.org

[gwest]

G-

 Here's another pic of my laying on my back taking the shot through the panel at the sun and a tree http://www.fieldlines.com/images/scimages/13763/BP_5.jpg

 The panels look good and I checked all with a metter. Since I'm so new at this let me asked a dumb question, what is Isc ?

[gwest]

G-

  How would I load test one of the panels?

[ghurd]

A power resistor (or array of power resistors) of about 120 ohms, and at least 25W.

The 60V and 30W peak means about 0.5A. Then you can see if all 4 are up to snuff.

Doesn't seem like much total power for a 48V system.  I would not build a 48V system around those panels.

I'd also say maybe someone with a 48V system would pay something for them to get you a small 12V panel, but they are not the preferred type, and they don't have frames.

Isc = short circuit current.

G-

[gwest]

 Reply to everyone,

  I do thank all of you for your help with my older BP panels. I have a man that can build me a controler for these for $250. That seems fair to me seeing what OutBack and other good companies charge for something of this nature. Also with a controller being built for these panels I can add on the other eight later without having to change anything. Again thank you all for your advice and help,I'm grateful.

         Greg