southace26
Active Member
Is there such things as a good solar panel or do you need to cover the entire transom and deck to get the charge you want?
solar panels
- Thread starter southace26
- Start date
nathanlee
Well-Known Member
I have two small 20w panels on the pushpit. I have not been connected to shore power for a week and a half, and I have no engine on the boat. I am writing this on laptop that's running on an inverter, and has been all week.
Modern solar cells will knock out plenty of power on a sunny day.
Modern solar cells will knock out plenty of power on a sunny day.
ccscott49
Well-Known Member
there are solar panels which are more suceptible to being partially shaded than others, cant remember which is which, but they do have a diode between each cell I think, anyway mine are the good type, I have 360 watts of panels, they do a fine job of running all my day needs and putting a little in my batteries. I am a power hungry boat.
Channel Ribs
Well-Known Member
The Spectralite range are excellent in terms of power for size and robustness:
http://www.alderneymarine.com/images/products/spectra.pdf
http://www.alderneymarine.com/images/products/spectra.pdf
marno
Active Member
Don't forget a good controller as well, they can make quite a difference. I have ordered one of these (it has an equalization feature) with MPPT.
misterg
Well-Known Member
[ QUOTE ]
Is there such things as a good solar panel or do you need to cover the entire transom and deck to get the charge you want?
[/ QUOTE ]
Oh yes.....
How deep do you want to go? /forums/images/graemlins/smile.gif
Firstly, separate the 'cell' technology from the panel design.
Bright sunshine is corresponds to an energy of ~1000 watts per square metre.
Depending on the type of 'cell', somewhere between 2 or 3% and maybe 30% of this is converted to electricity.
The rough order of efficiency goes:
Cheap (QA reject) 'thin film' cadmium telluride or amorphous silicon ~ 2-4%
Expensive 'thin film' CdTe / Si, maybe 8-10%
Polycrystalline silicon wafer maybe 8-12%
Monocrystalline silicon wafer maybe 15-20%
Monocrystalline gallium arsenide 20-25%
Tandem GaAs / germanium 25-30%
Concentrator GaAs / germanium 30 - 35%
(figures rough, from memory, and a few years old)
I doubt you'd find the last 3 on a boat, though.
Each panel will contain one or more 'string' of cells connected in series. Each string can't (generally) generate more current than the least efficient, cell in the string. (very good panels have bypass diodes across each cell to allow some output from a string even with a weak or shaded cell).
The number of cells in the string depends on voltage of the panel is designed to produce. The output of *all* solar PV cells falls with age and temperature, so all panels are over-designed to make sure that they give their *rated* voltage at some arbitrary service life and operating temperature.
Cheaper technologies, and cheaper cells generally degrade more, so require more cells in a string to achieve a given end of life voltage - i.e. the cell efficiency may look OK, but the cells will be connected up in the panel to generate excess voltage for most of it's life (which will just go into warming up your voltage regulator), instead of forming part of another string and generating useful current, so the panel efficiency in terms of *useful* power generated is lower. 'Thin film' cells generally degrade more than wafer cells; Good panels will have cells with low degradation, which are closely matched in performance.
The number and arrangement of the strings will determine how shade / fault tolerant the panel is. Thin film panels are fairly forgiving in this respect, which does something to redeem their (generally) poorer efficiencies.
Un-trimmed (i.e. round) wafers give more amps for your money than trimmed (i.e rectangular) ones, but you can't pack them efficiently onto a panel, so even if the cell efficiency of each type is the same, the efficiency will be lower for the panel made from un-trimmed cells.
Good panels will be designed to keep the cells as cool as possible, and be robust enough that they don't fail through mechanical failure or water ingress.
What area do you have available, and how many amps / volts do you want to generate?
Andy
Is there such things as a good solar panel or do you need to cover the entire transom and deck to get the charge you want?
[/ QUOTE ]
Oh yes.....
How deep do you want to go? /forums/images/graemlins/smile.gif
Firstly, separate the 'cell' technology from the panel design.
Bright sunshine is corresponds to an energy of ~1000 watts per square metre.
Depending on the type of 'cell', somewhere between 2 or 3% and maybe 30% of this is converted to electricity.
The rough order of efficiency goes:
Cheap (QA reject) 'thin film' cadmium telluride or amorphous silicon ~ 2-4%
Expensive 'thin film' CdTe / Si, maybe 8-10%
Polycrystalline silicon wafer maybe 8-12%
Monocrystalline silicon wafer maybe 15-20%
Monocrystalline gallium arsenide 20-25%
Tandem GaAs / germanium 25-30%
Concentrator GaAs / germanium 30 - 35%
(figures rough, from memory, and a few years old)
I doubt you'd find the last 3 on a boat, though.
Each panel will contain one or more 'string' of cells connected in series. Each string can't (generally) generate more current than the least efficient, cell in the string. (very good panels have bypass diodes across each cell to allow some output from a string even with a weak or shaded cell).
The number of cells in the string depends on voltage of the panel is designed to produce. The output of *all* solar PV cells falls with age and temperature, so all panels are over-designed to make sure that they give their *rated* voltage at some arbitrary service life and operating temperature.
Cheaper technologies, and cheaper cells generally degrade more, so require more cells in a string to achieve a given end of life voltage - i.e. the cell efficiency may look OK, but the cells will be connected up in the panel to generate excess voltage for most of it's life (which will just go into warming up your voltage regulator), instead of forming part of another string and generating useful current, so the panel efficiency in terms of *useful* power generated is lower. 'Thin film' cells generally degrade more than wafer cells; Good panels will have cells with low degradation, which are closely matched in performance.
The number and arrangement of the strings will determine how shade / fault tolerant the panel is. Thin film panels are fairly forgiving in this respect, which does something to redeem their (generally) poorer efficiencies.
Un-trimmed (i.e. round) wafers give more amps for your money than trimmed (i.e rectangular) ones, but you can't pack them efficiently onto a panel, so even if the cell efficiency of each type is the same, the efficiency will be lower for the panel made from un-trimmed cells.
Good panels will be designed to keep the cells as cool as possible, and be robust enough that they don't fail through mechanical failure or water ingress.
What area do you have available, and how many amps / volts do you want to generate?
Andy
Slow_boat
Well-Known Member
Swmbo recently met a chap who is a great DIY man and also into green technology. She reckons he makes his own solar panels at a fraction of the shop price and he's offered to show me how. If I learn anything, I'll report back here.
misterg
Well-Known Member
[ QUOTE ]
Swmbo recently met a chap who is a great DIY man and also into green technology. She reckons he makes his own solar panels at a fraction of the shop price and he's offered to show me how. If I learn anything, I'll report back here.
[/ QUOTE ]
Solar panels as in electricity, or solar panels as in hot water ?
If electricity, I would be intrigued to know how he does it.
Andy
Swmbo recently met a chap who is a great DIY man and also into green technology. She reckons he makes his own solar panels at a fraction of the shop price and he's offered to show me how. If I learn anything, I'll report back here.
[/ QUOTE ]
Solar panels as in electricity, or solar panels as in hot water ?
If electricity, I would be intrigued to know how he does it.
Andy
jimbaerselman
Well-Known Member
[ QUOTE ]
or do you need to cover the entire transom and deck to get the charge you want?
[/ QUOTE ] Depends how sunny the climate is! A 30 watt panel in the Med summer will provide some 20AH a day, about half of what a fridge will consume. Typically, that would be about 50cm x 150cm. Multiply by two to run a fridge. Multiply by four to run a 12 - 14m live-aboard.
UK climate? About 60% of that averaged over a summer.
Finland summer, 24 hours of daylight . . .
Carribean? Wind blows most of the time, you're better off with one of those whistling fans.
or do you need to cover the entire transom and deck to get the charge you want?
[/ QUOTE ] Depends how sunny the climate is! A 30 watt panel in the Med summer will provide some 20AH a day, about half of what a fridge will consume. Typically, that would be about 50cm x 150cm. Multiply by two to run a fridge. Multiply by four to run a 12 - 14m live-aboard.
UK climate? About 60% of that averaged over a summer.
Finland summer, 24 hours of daylight . . .
Carribean? Wind blows most of the time, you're better off with one of those whistling fans.
southace26
Active Member
thanks for the helpful info.....I currentlly run 2x maintance free 110amh house battreys and one 680cc lead acid battrey via a VSR, one 30watt solara semi flex paneland a 55amp alternator....my house use is around 5amps + 3amps for fridge....now im thinking running my fridge on and autopilot on a seperate 110amh battrey with a extra 85watt monocrystalline panel as to the link http://cgi.ebay.com.au/85WATT-PROSTAR-MO...1742.m153.l1262
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