How to make photovoltaic solarpanels to suit our boatdesign

Discussion in 'Boat Design' started by BertKu, Feb 14, 2010.

  1. BertKu
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    BertKu Senior Member

    Today, it is possible to get all the ingrediemts to make a good photovoltaic solarpanel. Sometimes the shape of the square panels does not suits the design of the boat and by making our own panel, we could get the right dimensions. Most of is need a panel in anyway, for our house, caravan or boat. Provided we are more costeffective then buying a complete panel.

    One has to bear in mind however that you need a number of cells in serial to get the right voltage at low ambient and higher ambient temperature. Also the regulator need some extra "juice" (voltage). The standard is 18 cells for 6 Volt and 36 Cells for 12 Volt system.

    I always prefer to put an extra 37th or 19th cell into the system, as then by low light levels or wrong angle of the lightbeam, still something is charging the battery.

    I am not an expert, but maybe together we can make some cost effective panels by exchanging some crucial details needed to make them.

    a) we need a reliable supplier for the cells.
    is this the one??? http://www.quadmodsusa.com/solarcells.html

    b) we need the best price for the cells.
    c) we need anodized alluminium or alluminium which is powdercoated.
    d) we need suppliers of hardened glass on which we can walk. 3,2 mm hardened glass.
    e) we need to discuss special shapes, like a circle, would that be nice to have it in such a shape.
    f) the connections, what is the best.
    g) the layer between baseplate and the very brittle solar cells and the next layer between glass and cells.
    h) what type of glue should be used. etc.

    Well shall we go for it to make our own panels??
     
  2. CDK
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    CDK retired engineer

    An interesting supplier. I think they buy and sell overstock items, so we must keep watching their offers. At this moment I saw only polycrystalline cells.

    Making your own offers new possibilities like following the curvature of a deck area. You could use clear resin instead of glass.
     
  3. BertKu
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    BertKu Senior Member

    That is what I was also thinking about, but what influence has UV penetration on the clear resin. Also, can one walk on the resin without cracking the cells. I was jumping on the solar panels without any problems, but they were round and had quite some space between the cells.

    Is there clear resin onthe market, at which UV has no long term effect?
    Bert
     
  4. jim lee
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    jim lee Senior Member

    You may want to look at the UV protected clear polyurethane resins. You'd probably need to heat cure them though.

    -jim
     
  5. bertho
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    bertho bertho

    interresting...
    perhaps can we use polycarbonate/lexan sheet to protect the cells? lighter and unbrackable? :rolleyes:
    it's any risque of condensation below the glass? or the cell are glued on it with a PU/acrylic resin?
    cheer's
    bertho
     
  6. BertKu
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    BertKu Senior Member

    When it comes to resins, etc I am not an expert and know nothing about it. I will need to consult a technical advisor from a resin company. We need to know whether it is easy to be scratched, otherwise we will loose too soon our efficiency.
    But, yes, it is something to look at.
     
  7. BertKu
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    BertKu Senior Member

    Will it scratch quickly?

    Well, I assume that one has seal the panel in such a way that no condensation can take place. When I made some very small panels, I vacuum sealed it, but the plastic I used, started to get yellow after a few years (I am talking about 30 years ago now). But I used hardened 3,2mm glass as top.

    Now we are considering to poor ????? over the cells and have a special shape.

    I assume one has a baseplate, thin stainless steel 304 or 316, bent it to the right curve needed for your boat ( not too much) , put a 2 - 4 mm ??? soft layer on it. Place all the solar cells on it, make the electrical connections, poor the resin over it and you have a solar panel according to your likings. Whether you are able to walk on it, is a big question. It depends how much the surface will bend. If too much, the cell will crack and your solarpanel will give a reduced output or open circuit.
    Bert
     
  8. CDK
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    CDK retired engineer

    I have a flexible panel that keeps the boats batteries topped up.
    Small cells embedded in silicone resin, probably a stainless steel foil as a base, a vinyl envelope sewn at the edge, the top layer is clear vinyl (like the rear window of a cabrio).

    We sit on it and stand on it and some cells are broken from a pencil or coin under the panel while someone stood on it, but as long as the straps aren't severed, even the broken cells contribute. Of course after 15 years the vinyl doesn't perform as well as glass anymore, but it serves me well.
    It was blown in the sea at least 10 times without any damage. A Siemens SM-55 panel I used on board for the same purpose once fell off, hit the sea rail and shattered into a million pieces.
     
  9. BertKu
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    BertKu Senior Member

    The problem always is, to get similar material like that, at places where you and I are living.

    The americans are lucky, they order and the next day
    it gets delivered to their doorsteps at a reasonable cost.
    That is indeed the problem with hardened glass, like a shower door. You can bend it, stand on it, but if a sharp item hits this type of glass, you lend up with a million pieces.

    Thus we agree then, we use a resin.
    Bert
     
  10. Ron Skelly
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    Ron Skelly RonS

    solar option for this design

    Re: for new design..I would be interested in specifications that can be produced by a solar panel, sizes of panels required, battery requirements etc?
     
  11. CDK
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    CDK retired engineer

    Availability issues

    Bert, I assume ordering solar chips and have them delivered in SA is not your problem. Do you have to pay tax and import duty?
    The interconnections wire and eutectic tin wire will also be no problem as you can get that from the same source.

    I found it almost impossible to buy chemicals in the USA because there is a lot of paranoia about liquids and airfreight. Can you buy bedding compound or other elastomers in SA? Silicone in cartridges are suitable only if there is no vinegar smell and the material is allowed to cure uncovered. But a 2-component product is much easier and can be covered with mylar, vinyl or polystyrene immediately.
     
  12. Paul No Boat
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    Paul No Boat Junior Member

    yeah, be careful how you word things on custom forms especially pertaining to electronics. I sold some old flashbulbs to a vintage camera collector in the yukon and postal customs held them for 3 weeks before satisfied and forwarding them on. when I inquired as to why I was told flashbulbs can be used as an iginter in a homemade bomb. who'd have thunk it?
     
  13. BertKu
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    BertKu Senior Member

    Yes, I do pay import duties and VAT (BTW)

    We have SASOL, which makes oil out of coal. As byproducts, there is a vast number of chemicals, even asperine. I will have to find out what is made locally and what not. I must speak to my neighbour who is a Dr. in metalurgie and is on the board of the company which controls all the materials coming out of the ground in RSA. Unfortunately, my wife made it clear to me, she is a chemist and bi-chemist, but in food technology. She told me, I am on my own when it comes to non food chemistry.

    Will need some time to get my Windows7 going. I am so fustrated, none of my 3 computers works anymore. I may consider to go back to WindosXP, I have no more e-mail. I have to dial into my service provider to read my messages. So much for the 30 odd updates I have received already on Win7 since Saturday. I am a Unix man, no virusses, no fustrations.
     
  14. BertKu
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    BertKu Senior Member

    Paul, it is not in my hand what is decleared on the Bill of entry, that is done in the USA. Lets hope that they have read your warning and are experienced enough to write some sensible customs declaration, like "Solar Cells, other semiconductors, no duty".
    Bert
     

  15. BertKu
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    BertKu Senior Member

    Ron, in principle you can make a solarpanel as large and as small as you want. However there are a few guidelines to follow. Most cells are between 0,5 Volt and 0,55 Volt each cell. To enable to charge a battery, you need enough cells to allow the Voltage regulator to do it's job.
    If you charge a Lithium single cell, with a Microchip single cell microprocessor, you need 6,8 Volt , i.e. 13 to 14 cells IN SERIAL.

    If you like to charge your 12 Lead Acid battery, you need 14,4 Volt to charge the battery and then the overhead of the voltage regulator, which need another 3 Volt at least. Thus you lend up with 36 cells in serial. I always say, make it 37, in case the angle of light inval is not so good anymore.

    The rule of the thumb is, approx 12 - 14% in practise per 1 square meter of sunlight inval at midday = 1000 watt (if you are lucky ) . i.e. If you have a square meter solar panels, you can expect 120 watt. There are some expensive solutions which may give you 160 watt.

    We even have information that with an inexpensive reflector, you could increase your output to 20%, but you need also 20% space. Nothing for nothing. But a reflector is cheaper than a 2nd solarpanel.

    Always use a diode between the panel and your equipment or battery.

    You can connect solarpanels parallel, provided the no of cells are the same and you use shotkey diodes between panels and center terminal. i.e. you have 10 panels parallel, you use 10 diodes all directing to the center terminal.

    Preferable a shotkey diode. I use a 10 Ampere diode at $ 0,70. The losses is very low, only 0,15 - 0,2 Volt at 5 Ampere. i.e. you loose 1 watt. You can charge a battery direct from the solar panel, provided the current is low and does not damage your battery. example. You have a 60 Amperehour 12 Volt battery and a 36 cell, 50 milliAmpere solarpanel. It will keep you battery charged and should not do your battery harm. But if your panel is 4 Ampere and 37 cells, you better use a voltage regulator.
     
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