TheBackShed.com

Forum Index : Solar : Price per watt

Author

Message

Shelly
Newbie

Joined: 22/12/2009
Location: Spain
Posts: 25

Posted: 08:58pm 10 Jul 2010

Copy link to clipboard

Print this post

A couple of months ago there were posts on the cost effectiveness of home-made panels. Prices were quoted in Au$ I presume. The cheapest panels I have found here are 1.7� per watt. The current rate of exchange today would make that Au$ 2.5 per watt. Apart from the problems of making a panel, does this price per watt seem reasonable? I have found on E-bay 400 watts of solar cells, with wire kit for 0.64� per watt. These are advertised as Grade A mono crystalline cells. Is the price difference sufficient to contemplate building your own? I think it possibly is. Any comments?

VK4AYQ
Guru

Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 11:50pm 10 Jul 2010

Copy link to clipboard

Print this post

Hi Shelly

My experience with homemade panels has led me to the conclusion it isn't worth the time for the few dollars saved.

The cost of the backing sheet and glass and a 1/2 tube of silicone and 4 hours work along with the cost of the cell kits totaled up is more than I can buy a completed panel with.

In saying that I still have 16 panel kits to finish, as I have already bought the materials, so that's a weeks work for the love of it.

The cells are very fragile, and from the ones I purchased there are a few cracked and broken ones from transit damage, also had to make a vacuum lifter to handle the cell strings once soldered together to avoid further damage. A pair of glass handlers, suction cap type to place the glass sheet over the cells to prevent contact damage is essential if you are a bit fumble fingered like me.

You will need a good temperature controlled solder iron to tag the cells if not already done as if the solder iron is to hot it will fracture the cells, and a flux pen to clean the cell pads before soldering is a big help. Use a piece of cloth lint free to put the cells on for soldering when tagging so you dont touch the cell, light cotton gloves helps to avoid contaminating the surface with hand oils. Remember that commercial panels are handled in surgically clean rooms by specially atired workers or robots.

Some of the first cells I made worked but where pretty rough and down on output. Also don't use plastic on the panels as some recommend, I found even the best commercial available plastic sheets yellows after two years in the sun. The special low iron glass is very expensive, but I found that good quality clear glass works OK with a slight reduction in output, not enough to worry about. I use 4mm glass and run a bead of silicone down the center of the panels to give a shock strip to absorb impact better, the only one that has broken is one my granddaughter jumped on when I had it laying on the ground testing output. It is a good idea to check the cell outputs to match them as closely as possible as I found that with the cells on the market even though they a sold as A grade they are still rejects from the factory and not consistent spec.

If you are doing a full array of 2.5 kw you will save a $1000 if all goes well, the decision is up to you and how much spare time you have.

All the best

Bob

Foolin Around

Shelly
Newbie

Joined: 22/12/2009
Location: Spain
Posts: 25

Posted: 08:33pm 12 Jul 2010

Copy link to clipboard

Print this post

Thanks for the reply. Out of interest what did you make your frames from? Apart from your granddaughter have you had any problems with the panels? I want 400 / 500 watts more for my system. I'll probably buy a small kit and practice. If I'm not successful at least I won't have wasted a lot of money but have had a bit of fun trying.

VK4AYQ
Guru

Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 11:24pm 12 Jul 2010

Copy link to clipboard

Print this post

Hi Shelly

I used 13 mm alum channel for the frame, it has a 10mm opening that allowed for the backing sheet of 4.5 mm cement sheet and 4mm glass and a silicone bead between the cement sheet and glass, Give the cement sheet several coats of white paint matt finnish, both sides to seal it from moisture. The channel gets a bead of silicone sealer before it is pushed into place to assure a good seal. With the corners beveled at 45 degrees it looked neat enough, and was quite robust, haven't had much bad hail so cant say how that would go, but I have my old solar Hot water collector done with 4mm glass and it is 25 years old.

When mounting the frames I used some soft rubber between the frame and the mounting rack to act as a shock absorber. The bead of silicone down the center between the cells helps support the glass also, when placing the strings of cells on the backing put 3 small dots of silicone behind each one to stabilize the cells and make sure to place a flat panel or glass to set them down before the silicone sets or they will break.

Moisture in the panel can be a problem, assemble on a hot dry day day low humidity and seal the wire holes with silicone, I used silicone that they make fish tanks with, for best seal and adhesion. Be sure to clean the glass, as some I had was coated with an oily residue. I put a sprinkle of silica gell crystals inside the panel to absorb moisture, so far no problems with moisture.

Best of luck with your project.

All the best

Bob

Foolin Around

KarlJ

Guru

Joined: 19/05/2008
Location: Australia
Posts: 1178

Posted: 11:52am 13 Jul 2010

Copy link to clipboard

Print this post

I wouldnt even contemplate it. the cost vs a commercially available panel
as bob suggests makes it out of the question.
can buy complete panels 185W for ~$500 here in Aus and your looking at $100 for the cells + glass, think $80-100 for 4.0mm toughened low iron glass, think $40 to frame it then resins tedlar etc etc etc etc etc.
all for a module thats lucky to last 2-3years, hell even the ones made by robots in specialised facilities are sometimes lucky to make 5 years.

I work out at RISE at Murdoch university and the solar panel graveyard is just that and these are panels made by top name manufacturers and at 20years old they are all looking very stuffed indeed.

Luck favours the well prepared

KarlJ

Guru

Joined: 19/05/2008
Location: Australia
Posts: 1178

Posted: 11:54am 13 Jul 2010

Copy link to clipboard

Print this post

BTW apart from the fact they are currently sold out Solon are competitive at 2 euro's a watt.
chines manufacturers are selling into europe right now at 1.40 euros a watt.

Luck favours the well prepared

Print this page

To reply to this topic, you need to log in.