Making best use of shore and passive power sources

Discussion in 'OnBoard Electronics & Controls' started by jamesgyore, Jun 10, 2013.

  1. jamesgyore
    Joined: Sep 2011
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    jamesgyore Senior Member

    Thanks for the link, an excellent link I'll keep bookmarked.

    I've become rather engrossed in the topic and have since learned that wiring solar and turbine regulator/chargers together to batteries is not so smart.

    It seems that electrical sibling rivalry is a very real issue, and here I was joking about it.

    Until early this morning I had no idea that chargers use time/timing as part of their charging algorithms, and the voltages generated by one charger and the charge step it is in can adversely influence the behaviour of the other charger... Pays to read the fine print.

    So, I'm better informed, but non the less back at square one, wishing for a simple and tidy single box solution that knows what is going on.

    I'm at a loss to understand why solar or turbine energy singularly is so easy to implement but having both installed on the same boat becomes such a messy proposition.

    I've done a little window shopping on ebay, and have seen a few communist chinese regulator/chargers that integrate both turbine and solar inputs but do not offer a dump load feature to milk excess energy for something useful like generating heated air or water.

    Should I be giving thought to investigating regulators without charge functionality for both solar and turbine that feeds a single DC-DC charger?
     
  2. John Kane
    Joined: Jun 2013
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    Location: Bahamas

    John Kane Junior Member

    I would suggest you look into a dc generator and a Victron Quattro inverter/charger. This will take care of your renewable energy Ac/dc and charging requirements while saving weight and fuel. The dc generators are also very quiet.
     
  3. BertKu
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi James,

    If it is not an error, you have a battery bank of 6 x 2000 x 2.15 Volt = 25.8 Kwh i.e. weight will be approx 600 kg

    For your size of 25 feet boat, you need about 2 Kw motors to sail at a reasonable pace with smooth or low waves. To charge your and supplement your battery bank, you need at least German Solar panels with an efficiency of 18% or greater and a spectral frequency range, that by low light, or cloudy condition, you still have energy coming in. Those panels are expensive, but it is worth it.

    You need thus at least 1 Kw of energy coming into your batteries (50%), to go a reasonable distance, just for your electric motor, whether brushless motors (recommended) or AC motors with lower efficiency. 1 Kw of energy means at 12h00 direct 90 degrees sunshine on your panels: 6 square meter at least.

    I recommend to fold the panels up 3 at the one side of your boat and 3 at the other side. Weight will be approx : 324 kg, just for your panels.

    I would consider to buy as much as 12 V (or 24 Volt) appliances (more expensive) en don't bother about 230 or 110 Volt AC. Have LED 12 Volt lights and 12 Volt fridges.

    One hell of a big 3 Kw - 5 Kw AC to 12 Volt DC charger, which takes 5 to 6 hours to charge your battery bank after a day trip. Trips including nights, you don't have a big enough battery bank.

    Is your boat good enough to handle an extra 1000kg? I doubt it.

    Best regards
    bert
     
  4. jamesgyore
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    jamesgyore Senior Member

    Hi there Bert,

    I am slogging through a number of text books. You have summarised very well the nature of my dilemma and the technicalities I need to appreciate.

    The boat design is certified to B6. I have a self imposed B2 down-rating and robbed Peter to pay Paul. Using that weight saving to allow for the heavier battery arrangement.

    You're quite right... I'm still overweight, as my crude and inelegant spreadsheet calculates 1272Kg.

    One of the text books describes in little detail, an arrangement where stored energy is sufficient for marina/anchorage manoeuvring but little more. A generator/charger is also described as an emergency source of energy.

    One rather clever german chap already going about a project similar to my own ambition sent me pics of how he temporarily hoists flexible solar panels to conform to the main sail shape while under sail. He suggests it is not particularly efficient but does work simply because he has increased surface area exposed to light. On his transom he has two solar panels that can be aimed at the sun.

    I'm rather engrossed in the topic and marvel at the many and varied subjects I've been introduced to by way of building a small yacht.

    As much as I had hoped for a cute little magic "black box", I suspect I'll have to make do with a precariously balanced mish-mash of boxes and technologies.
     
  5. BertKu
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi James,
    Don't give up your dream. I personally would do it differently. I would place 2 banks of 42 x 24 Ah x 12 Volt deep charging SLAB's (Sealed Lead Acid batteries) in series and parallel. Whereby the plus 36 Volt bus-bar is connected via 15 x 80 Ampere Schottky diodes. You need 36 Volt to drive brushless motors and keep the current lower. A conversion from 12 Volt to 220 Vol AC is a nightmare to do it efficiently. I would stick to 75 KV/V i.e. the motor runs at 12 Volt 75 x 12 = 900 rpm. But at 36 Volt , your speed is 2700 rpm. To have 2 motors at 1 Kw each, you need thus 33 Ampere per motor. This type of current , one can live with.

    This battery configuration will be also approx 25 kwh. (A small example in Lithium house bank 3 threads further up).
    Weight?
    Lucky only 84 x 7 kg = 588 kg, with a little overhead of maybe 2 kg for connections, brackets and buss-bars.
    The solar panels, you may have to come up with a flexible solar solution, to suit the shape of your boat. Although many universities have come up with higher efficiency solutions, I haven't seen any manufacturer bringing it into production in a practical way.
    Bert
     
  6. jamesgyore
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    jamesgyore Senior Member

    Most interesting, you've given me a great deal to think over and learn about.

    Might you or others know much about a South African eccentric that described the use of mineral infused quarts lenses layered over PV silica chips to improve on yield/harvesting by way of refraction and narrowing of light waves in non directed panel applications?

    Regards,

    James
     
  7. BertKu
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi James,
    That can only be somebody from the Pretoria University or Stellenbosch University. They both have equipment to slice and make wafers and make Integrated circuits on a small scale. I don't think RAU, University of the North and others, nor Wits university deals with the production of wafers, included solar cells.
    I will ask my neighbor who is a Dr. in metallurgy and could maybe know about such eccentric. However one has only so many photons per square meter to catch. The rest are tricks to increase, by means of lenses, reflectors and catching the photons which "falls trough the net" by having double layer cells. The second layer catches the photons which are due to the necessary gaps in the first layer. Sadly one cannot really increase the number of photons per square meter. Theoretically it is 26%.
    Bert
     
  8. CDK
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    CDK retired engineer

    I read about that, probably somewhere in the very long batteries & new technologies thread.
    But the promised breakthrough never came.
    Anything put between the solar cell and the sun attenuates the radiation to a certain degree and reduces the cell's efficiency. The best performers are the panels in orbit that have no glass panes over them, just a thin coating to filter out harmful wavelengths.
    The only technology that does work is a cooling system that removes the heat and uses thermo-electrical devices to generate additional electricity. But I've not seen any commercial application, probably because of the extra costs involved.
     
  9. BertKu
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    BertKu Senior Member

    Hi CDK,
    What could James and I do to make the solar system lighter. So far hardened glass is still the best to protect the cells. I have 2 heavy 240 watt solar panel, which folds up to protect each other when the boat is stored or during rainy days.
    But the weight is 18 kg each panel, while the cells themselves and tracks are only probably 1,0 kg. Have you already read about a layer one could paint or poor over the cells to make a 1 Kw system ourselves. Similar of the solar car of the Delft TU. If the solar weight is only 100 kg, for a 1 Kw system + 600 kg for 25 Kwh battery system, James would be able to materialize his dream. An engine is normally between 200 and 500kg included some basic battery system in anyway, which he does not have. Thus with an extra 200kg or 300kg more than the left out weight of an engine, for a 25 feeter it could be done. Bert
     
  10. BertKu
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    BertKu Senior Member

    James could consider some contraption, which shifts the solar panels in or out.
    Sketch a) He could fold them up at the back and provided the wind is not enormously strong.
    Sketch b) He could consider a system, like a garage door, roll them out on a contraption which gives him some sun shadow also.
    Sketch b) He could make a kind of solar sail. Use the wind in his advantage or fold them up and out.

    He could also blow a balloon in the air with a cable and a solar panel. But that is science f(r)iction.
    Bert
     

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  11. jamesgyore
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    jamesgyore Senior Member

    I think you're into something Bert. Take a look at this:

    http://www.schionningdesigns.com.au/troublemaker-series

    Note the unusual trampolines located at the quarters. I'm not at all sure what purpose they serve. Mounting a couple of panels in such a manner might be satisfactory.
     
  12. BertKu
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    BertKu Senior Member

    Hi James, I am a little confused. Are you busy building a yacht, or are you considering a yacht or is it just a dream?. Nothing wrong with any dream, as long you are able to put your shoulders under it and you make it real and no longer a dream, even if it takes 2 or 3 years. The ideal placement for solar panels are 90 degrees with the sun. Thus if you have them flat, like most of the yachts have them, then the daily power supplied is much less and may be not enough for your ideal propulsion. i.e. electrics only.
    Bert
     
  13. jamesgyore
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    jamesgyore Senior Member

    Chuckle, I'm in the early stages of construction. The bulkheads are already constructed and I'm just waiting for better weather before I set up the jig in the front garden.

    While I have very little worthy of photography at this stage, a Brazilian fellow is well ahead of me. On or about October 10, I expect have one of these decorating my front lawn:

    http://www.yachtdesign.com.br/01_portugues/noticias/en_destaque_137.html
     
  14. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member


  15. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

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