Another solar installation question

[Deron Kazmaier]

I have been saving up for materials to build a wind mill tower, but a recent sale item at sun electronics (sunelec.com) has got me thinking that adding solar now might be a good idea. These particular panels (Kaneka GSA-60) are just less than a $1 / watt which is a great price. Reviews put the panels as reliable, so that is not a worry. However, I've done far less research into solar than I should for this big a project so here I am hoping to bridge the gap between what I know and what I need to know.

What I am thinking is 20+ panels running through an Outback FLEXmax 60. The panels Voc is 92, and the Vmp is 67.

What does worry me is three issues.

One is that I would like to move to a 48v battery bank. Will the panels have enough "head room" to still charge a 48v battery bank. I'm afraid that early/late day sun won't produce enough voltage to charge the bank, and with a Voc of 92, I can't place 2 in series and stay under the FM60's max Voc of 150. In fact, will MPPT really buy me much in this case. Also, it appears that in summer heat these panels might be lucky to put out 54v?

The other is can I parallel that many panels together? Fuse rating is 7a. I can't get my head around how that would apply here in a (largish) parallel string, but I would rather find out now.

Lastly is mounting. I have plenty of ground space, but not roof space, and the wind is high around here at times. Gusts up to 40mph today! Each panel is roughly 39" x 38". What would be the most economical way to mount these on the ground and be tiltable? I would never want to track with these. Cheaper to buy extra panels at this pricing. I am thinking of 2x5 groups which makes a panel about 17' x 7' (parallel wired 10a group). What about 4 wood posts at the corners, 2x10 on a diagonal (roughly  between the front and back posts on each end, and some kind of 17' steel run horizontal. I think each panel needs 2 runs, so that would be 4 horizontal runs. I would need some kind of diagonal to keep racking to a minimum.  Is 17' too long? I hate to dig to many holes out here in the frozen tundra! Sounds too long now that I write it. a 17'x7' sail would have a lot of force on it. Don't want to crack them puppies! The good news is that the wind is usually WNW or ESE so more of glancing blow than straight on. Maybe add an extra set of posts in the middle so just over 8' spans?

Thanks,

Deron

[TomW]

Personally I think building solar panel racks out of wood is a recipe for disaster. Obviously it can be done but how long will it last and will it stand up to that big storm or 3 feet of wet  snow load?

We get both here and storms of fierce magnitude happen everywhere. Just imagine the wind or snow loading on that 120 square feet of surface.

Wood flexes, expands and contracts which will stress the panels. It rots and requires treating to last. Solid and rigid joints can be tricky even for a professional wood butcher where everything is constantly being worked by the wind.

Mine are mounted to 3" heavy angle iron with Stainless bolts and nuts as standoffs to keep the iron and aluminum panel frames isolated.  All attached to a sat dish polar mount rated for a 1500# dish.

Think of it as an investment and not one you want to cut corners on, either.

Just an opinion.

Tom

[Bruce S]

Deron;

 Sunelec is on my radar too, they have some pricing now that makes buying anymore HF panels obsolete.

I will 2nd Tom W's stance on the mounting. I have 5 of the HF panels linked together in an area that is somewhat wind protected, but even with that I have them rigged with 1/4 angle iron around the perimeter of them and between using SS not/bolts to keep them where they be.

Go with a best in breed mounting and have one less worry.

Cheers

Bruce S

[Tritium]

You might want to look at this write up on these panels. They claim not to sag like silicon during summer heat.

http://www.innovativesolar.com/solar-modules-196/kaneka-200/60-watt-265.html

If I can secure funds before they sell out I will buy a pallet of them.

I would think they would be a very good fit with a MPPT controller and a 48VDC nominal battery bank.

Thurmond

[Bruce S]

Tritium;

Nice price, but  a company in Florida has them at a lower price.

http://sunelec.com/index.php?main_page=product_info&cPath=5&products_id=543

Rich introduced me to this company back in December and I've not order any other PV from HF. the price from them is much better for better panels.

I should ask over in Reviews if ANYONE has had problems with them.

Cheers;

Bruce S

[Deron Kazmaier]

That is why I asked! I was going to use steel for the actual frame, but I can be easily swayed to all steel if I know what to use. I just don't have any practical experience with steel.

These each have 4 mount holes (two on each side), so where would I find out a good/recommended steel dimension for a given length? 2 pieces of 3" heavy (1/4"?) angle iron would be good for 3 panels (120"), 4 (160"), 5 (200")?

Would the same angle iron be suitable for the legs? Or would just two legs with a pivot point be more economical? (Not sure if the added complexity pays off)

Thanks!

[cr8zy1van]

I have bought panels from Sunelec in the past and have been very happy with their product. The price is right and getting better and their shipping rates are reasonable. They now have a warehouse in Phoenix so us west-coasties have better options.

One think that did not impress was their overall customer service. Unless you know what you want, and what questions to ask, don't bother asking them for help. A simple 6 panel setup for a well pump had them sending me all over the place and getting passed from person to person, eventually to be ignored by the sales rep. (one less commission for him!)

Do your homework, ask questions on this board, and then order.  

[ghurd]

Other than sometimes having 3 physically different panels with 2 different voltages listed at the same time with the same part number,

Things like this can happen...

http://www.fieldlines.com/hotlist/add/2009/2/22/145152/526/displaystory//

G-

[Tritium]

I deal with sunelec. The link was for information only. I see sunelec has now added the same information to their site.

Thurmond

[Ungrounded Lightning Rod]

One is that I would like to move to a 48v battery bank. Will the panels have enough "head room" to still charge a 48v battery bank. I'm afraid that early/late day sun won't produce enough voltage to charge the bank, ...

Lower light levels drops CURRENT, not voltage.  (Voltage will drop if you load the panel too hard, due to lack of available current to keep the voltage drop high on the load.  But if you load it with something like a battery you'll charge fine - just slower - in lower light levels.)

[Deron Kazmaier]

Ok, thanks for clarifying that issue. I guess I'm of to get some panels. I can always figure out mounting after the fact. I'm thinking about driving down to pick them up in Phoenix, which would give us a nice road trip and give us the chance to pick up a few other things along the way.

I might see if any place along the way has a good pricing on batteries... Never enough time or money ;-)

Deron

[zap]

The hotlist link only worked for me when I was logged in.  For those not logged in, the story ghurd is referring to is this one:http://www.fieldlines.com/story/2009/2/22/145152/526

[ghurd]

Thanks Zap.

I unsuccessfully looked for that story many times.  

When I found it yesterday, it went straight into my hot list.

G-

[Ungrounded Lightning Rod]

When mounting them be careful about how things get shaded as the sun moves around.  The output current is limited by the current of the most shaded cell (or parallel group of cells) in the series string.