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Solar boats
- Thread starter ken 120
- Start date
http://solarboatchronicles.com
Is the link. I note that 45 miles is the longest run they have made in day. It will be interesting to see how that works out for crossing the Gulf of Mexico--or if they do the rim. This seems to imply that there is not a lot of reserve with batteries. Even now, if there is adverse wind or current, the boat slows way down...
I did find some techincal details:
"Powered entirely by 15 245-watt solar panels strapped to the vessel's hull and roof, the Ra sports two Torqeedo 4,000-watt electric motors that run off a current from a deck of 12-volt batteries. A separate electrical system powers GPS, radio, cellphone and onboard computers.
Shortly after launching, Greer discovered that the batteries were inadequate for heavy seas. Although able to make 12 knots on the smooth Suwannee River, the boat slowed to a crawl once it hit the Gulf of Mexico."
Apparently the voyage started over a year ago, and then was delayed. I wonder if there is some battery charging when the boat is at dock?
Interesting project--
Is the link. I note that 45 miles is the longest run they have made in day. It will be interesting to see how that works out for crossing the Gulf of Mexico--or if they do the rim. This seems to imply that there is not a lot of reserve with batteries. Even now, if there is adverse wind or current, the boat slows way down...
I did find some techincal details:
"Powered entirely by 15 245-watt solar panels strapped to the vessel's hull and roof, the Ra sports two Torqeedo 4,000-watt electric motors that run off a current from a deck of 12-volt batteries. A separate electrical system powers GPS, radio, cellphone and onboard computers.
Shortly after launching, Greer discovered that the batteries were inadequate for heavy seas. Although able to make 12 knots on the smooth Suwannee River, the boat slowed to a crawl once it hit the Gulf of Mexico."
Apparently the voyage started over a year ago, and then was delayed. I wonder if there is some battery charging when the boat is at dock?
Interesting project--
journey on
New member
Bob, using the numbers you gave, here are some interesting results.
First, 15ea 245 panels gives 3700 watts, max when pointed directly at the sun, which on a moving boat isn't possible. So, how about an average output in the daytime of 1800 watts (50% of rated.) Compare that to the 4000 watt (ea) electric motor, or 8000 watts when running at full power. There must be a really big set of batteries on that boat, both to store the power needed by the motors and to allow for the pointing inefficiency and limited daylight (~12 hrs, eh?.)
Second, the area of those panels is ~300 ft^2, say 30x10. I've used 12 watts/ft^2 based on the panels I've installed at our house. This would be tough install on a boat and to point at the sun.
So the power for going 45 miles certainly doesn't come from the panels, but mostly from batteries. It also means you're traveling at displacement speeds (6 knts?) This means that you're docked a large part of the time. Of course when you're docked you can use shore power, as mentioned above, though their web site says they're only going to use solar power.
And, if they're to go 6600 miles, they have to leave the ICW. Their site shows Florida waters and up the ICW to NC.
While I applaud their willingness to develop a new technology, solar powered boats aren't practical for us cruisers.
Boris
First, 15ea 245 panels gives 3700 watts, max when pointed directly at the sun, which on a moving boat isn't possible. So, how about an average output in the daytime of 1800 watts (50% of rated.) Compare that to the 4000 watt (ea) electric motor, or 8000 watts when running at full power. There must be a really big set of batteries on that boat, both to store the power needed by the motors and to allow for the pointing inefficiency and limited daylight (~12 hrs, eh?.)
Second, the area of those panels is ~300 ft^2, say 30x10. I've used 12 watts/ft^2 based on the panels I've installed at our house. This would be tough install on a boat and to point at the sun.
So the power for going 45 miles certainly doesn't come from the panels, but mostly from batteries. It also means you're traveling at displacement speeds (6 knts?) This means that you're docked a large part of the time. Of course when you're docked you can use shore power, as mentioned above, though their web site says they're only going to use solar power.
And, if they're to go 6600 miles, they have to leave the ICW. Their site shows Florida waters and up the ICW to NC.
While I applaud their willingness to develop a new technology, solar powered boats aren't practical for us cruisers.
Boris
Boris,
Reading thru their blog and some of the media blogs etc--they are traveling at slower speeds--sometimes 2 to 4 knots--thus using less than the max consumption of the motors. The celebration at 45 miles--lets say that they were running 10 hours--that is 4.5 miles per hour.
They don't seem to run at night or when the conditions are adverse--real cloudy, wind or adverse current.
Most of the solar craft--such as the one which crossed the Atlantic follow the traditional trade wind routes--they pick up both wind effect and the currents--the actual speeds are about half of what a sailboat would make. For example the Solar across the Atlantic followed the same route we did in 15 days--but they took about 32 days.
There is a large solar boat "Planet Solar" which is about 120 feet long:
"The boat is powered by solar panels that are 75 feet wide and 115 feet long. The 29,160 solar cells on board provide a generative capacity of 93.5 kilowatts of electrical power, allowing the vessel to reach speeds of up to five knots (5.75 miles per hour). " So again you have a vessel which is cruising at less than half of its predicted hull speed. This boat claims to have enough battery power to run 24 hours a day for 3 days (but don't say the speed).
Reading thru their blog and some of the media blogs etc--they are traveling at slower speeds--sometimes 2 to 4 knots--thus using less than the max consumption of the motors. The celebration at 45 miles--lets say that they were running 10 hours--that is 4.5 miles per hour.
They don't seem to run at night or when the conditions are adverse--real cloudy, wind or adverse current.
Most of the solar craft--such as the one which crossed the Atlantic follow the traditional trade wind routes--they pick up both wind effect and the currents--the actual speeds are about half of what a sailboat would make. For example the Solar across the Atlantic followed the same route we did in 15 days--but they took about 32 days.
There is a large solar boat "Planet Solar" which is about 120 feet long:
"The boat is powered by solar panels that are 75 feet wide and 115 feet long. The 29,160 solar cells on board provide a generative capacity of 93.5 kilowatts of electrical power, allowing the vessel to reach speeds of up to five knots (5.75 miles per hour). " So again you have a vessel which is cruising at less than half of its predicted hull speed. This boat claims to have enough battery power to run 24 hours a day for 3 days (but don't say the speed).
journey on
New member
Bob,
The solar panels on that 120" boat have an area of 8600 ft^2, which gives an estimated output of 100 Kw @ 12 W/ft^2, agreeing with their 93 Kw. So my assumption makes the estimate for commercially available panels of 12 W/ft^2 reasonable. and apparently that's what they use. And that's only if the panels are pointed at the sun, which requires an active 2 axis stabilization system.
So, commercial panels weigh ~2.4 #/ft^2. For the area given above, the weight is 42,000 # or 21 tons. I assume they can strip some weight off, say 30%, so the panel weight is still 15 tons. From my panels, this seems optimistic, since only the mounting frame is separable.
So again, they have a lot of batteries and when those are depleted, they're dead in the water. So you can go for 3 days and then wait for a couple of days to recharge? And one may assume they have a lot of batteries to permit running when there is no solar panel power ( not pointed at sun, morning, afternoon, night.) and batteries are heavy, even the latest technology, so lets estimate another 10 tons?
OK, now they have a power generating system that weighs 25+ tons for the basic components, which lets them run at slow speeds for 3 days, and then wait for a recharge.
Our daughter, Dorothy has a Nissan Leaf, an all electric car, courtesy of her husband, Phil. That car has a hard range of ~60 miles, so they can't bring it down to visit us (110 mi trip.) Phil also has a diesel which he runs on biodiesel, and solar panels on his house. Without people like Phil, we don't move forward, but there is some pain there.
Again, I applaud the boat for developing a system which shows what can be done. And Phil for trying new ideas. But I think I'll stick with petroleum for the foreseeable future. Though in balance, I have 4 Kw of solar panels for the house, since we live on air conditioning.
Nuff said, Boris
The solar panels on that 120" boat have an area of 8600 ft^2, which gives an estimated output of 100 Kw @ 12 W/ft^2, agreeing with their 93 Kw. So my assumption makes the estimate for commercially available panels of 12 W/ft^2 reasonable. and apparently that's what they use. And that's only if the panels are pointed at the sun, which requires an active 2 axis stabilization system.
So, commercial panels weigh ~2.4 #/ft^2. For the area given above, the weight is 42,000 # or 21 tons. I assume they can strip some weight off, say 30%, so the panel weight is still 15 tons. From my panels, this seems optimistic, since only the mounting frame is separable.
So again, they have a lot of batteries and when those are depleted, they're dead in the water. So you can go for 3 days and then wait for a couple of days to recharge? And one may assume they have a lot of batteries to permit running when there is no solar panel power ( not pointed at sun, morning, afternoon, night.) and batteries are heavy, even the latest technology, so lets estimate another 10 tons?
OK, now they have a power generating system that weighs 25+ tons for the basic components, which lets them run at slow speeds for 3 days, and then wait for a recharge.
Our daughter, Dorothy has a Nissan Leaf, an all electric car, courtesy of her husband, Phil. That car has a hard range of ~60 miles, so they can't bring it down to visit us (110 mi trip.) Phil also has a diesel which he runs on biodiesel, and solar panels on his house. Without people like Phil, we don't move forward, but there is some pain there.
Again, I applaud the boat for developing a system which shows what can be done. And Phil for trying new ideas. But I think I'll stick with petroleum for the foreseeable future. Though in balance, I have 4 Kw of solar panels for the house, since we live on air conditioning.
Nuff said, Boris
Robert H. Wilkinson
New member
Boris, your calculations raise a question in my mind about their seakeeping. Do they add ballast ?? According to your figures the weight of the batteries would not offset the weight of the solar panals. They would also not have large fuel tanks like a normal cruiser to add weight low in the keelo .
Even with ballast All that weight up top can't be good. ,,,,, now that I have thought about this some more - I REALIZE I WAS thinking monohull. The cat hull will probably bbe less succeptable to top heavy problems.
A lot of "off grid" systems use 2 banks - 1 is charged while the other is in use. This usually works best on a solar only system because it requires a large array to generate enough amperage for proper charging - hense 2 small banks better than 1 large bank.
Regards, Rob
PS sorry for all the typo's - using my daughters laptop - no backspace key :?
Even with ballast All that weight up top can't be good. ,,,,, now that I have thought about this some more - I REALIZE I WAS thinking monohull. The cat hull will probably bbe less succeptable to top heavy problems.
A lot of "off grid" systems use 2 banks - 1 is charged while the other is in use. This usually works best on a solar only system because it requires a large array to generate enough amperage for proper charging - hense 2 small banks better than 1 large bank.
Regards, Rob
PS sorry for all the typo's - using my daughters laptop - no backspace key :?