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Old 12-10-2007, 00:36   #1
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Question Liveaboard solar power


ive read around and searched the forums and internet quite a bit but still am pretty confused on this subject. let me give you a quick background, then ask kindly if anyone could give some information.

im moving aboard my 69 columbia 26 mkII "miss julia anne" within the next month. the boat is ready for me, minus electrical power and a couple small appliances! i will be purchasing solar panels, misc. controllers and a new battery bank within the next week or two. i know the first step is to do an electrical use survey. quite a few of the things i will be using wont be purchased until after installing the solar system during my final shopping trip and last minute purchases online, so i dont have exact figures and this is kinda throwing a wrench in the gears of my solar survey.

basically all I will use electrically is minimal cellular phone charging, a couple hours a day of a small 12v portable tv (12" size range), a couple hours a day of am/fm radio, a couple hours a day of vhf monitoring, minimal bildge pump use, occasionally charging my cordless power tools, the anchor light at night, occasional deck light, 1 or 2 small 12v cabin fans a few hours a day, and a couple small in cabin lights (combined a few hours a day).

aside from that, i may eventually get a laptop to use on the boat so i would need to figure that in also. no fridge and no a/c unless i could figure in a small 12v portable cooler/heater (found a new one on ebay for $75... the kind that keep food 40 degrees less than ambiant... for occasional use)

ok, with that in mind... what wattage, and how many solar panels would be recommended? and how many deep cycle 12v marine batteries would i need to setup? i have found some pretty decent prices on ebay for new solar systems (panel, wire + controller) and could buy the batteries locally (walmart... etc.).

i have not been able to find any detailed "how to" guides for setting up this system either... i would hate to setup this expensive system just to fry it because of some shady internet how-to guide!!

im sorry for the long post, and for needing so much information but i have no previous knowledge on solar power and have not been able to find the information that i need yet, online or in person. i can learn this stuff quickly if i can only get the initial help and/or reading material that relates to this.

thank you very much for your time and in advance for your replies.


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Old 12-10-2007, 00:37   #2
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oh... i live in sw florida on the gulf, if that matters on sun exposure per day...

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Old 12-10-2007, 03:02   #3
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I’m not certain you estimated power usage is realistic; bit FWIW, here’s a very rough Daily Power Estimate (based upon your criteria):
3 Hrs cellular phone charging 3 Hr x 25W = 75 Watt/Hours
2 Hrs 12" -12v portable tv 2 x 25W = 40 W/Hr
2 Hrs am/fm radio 2x 10W = 20 W/Hr
2 Hrs vhf monitoring 2 x 0.5W = 1 W/Hr
Hr bilge pump use 0.5 x 100W = 50 W/Hr
12 Hrs anchor light 12 x 20W = 240 W/Hr
Hrdeck light 0.5 x 20W = 10 W/Hr
2 Hrs12v cabin fans 2 x 5W = 10 W/Hr
2 Hrs small in cabin lights 2x 15W = 40 W/Hr
2 Hrs laptop 2 x 25 W = 50 W/Hr

Sub-Total = 526 Watt/Hrs consumption, for which I’d recommend at least 180 Watts of Solar array.

? charging my cordless power tools =20W/Hr
? Hrs12vThermoelectric (Peltier) Cooler 100 Watts

For DC system electrical load requirements, refer to ABYC E-11.10., and complete TABLE II

Some Typical (approximate) Current Draws:
(Amps x 12.5 V = Watts) (Watts x Hours = Watt/Hours)
Device - Amps
10 Watt Anchor light 0.8 amps
20Watt Anchor Light 1.6
Anchor windlass 150.0
Autopilot 0.7
Bilge blower 6.5
Cabin fan (efficient) 0.2
Cabin fan (oscillating) 1.2
Cabin light (8w fluorescent) 0.7
Cabin light (25w incandescent) 2.1
CD player 0.2
Chart light (10w) 0.8
Compass light 0.1
Computer (laptop) 2.5
Spreader/deck light (20 w) 1.7
Depth sounder 0.2
DVD player 0.3
Gas detector 0.3
Gas solenoid 0.6
GPS 0.5
Ham radio (receive) 2.5
Ham radio (transmit) 30.0
Inverter—standby 0.2
Microwave (700 w) 115.0
Pump—bilge 15.0
Pump—freshwater 3.0
Pump—shower sump 2.0
Pump—washdown 6.0
Radar 4.0
Reading light (10w) 0.8
Refrigerator 5.5
Running lights 2.5
Running lights—Tricolor 0.8
Spotlight 10.0
Television (13-inch) 3.5
Toilet 40.0
Speed log 0.1
SSB (receive) 2.5
SSB (transmit) 30.0
Starter 150.0
Strobe 1.0
VCR 2.0
VHF (receive) 0.5
VHF (transmit) 5.0
Waste treatment 45.0
Watermaker (6 gal) 20.0
Weatherfax 1.0
Wind indicator 0.1
Gord May
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Old 12-10-2007, 03:55   #4
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wow, incredible!! thank you so much for the information, that is exactly what i have been unsuccessfully searching for, for some time now!!

i think i might be able to skimp on a few of the items, such as cabin lights (would be LED... just found a 4 LED cluster 12v @ 0.025A) cell phone... it is only for emergencies and would be off most of the time, only needing to be charged on rare occasions. and might be able to eliminate a tv/radio/vhf on most days (id rather be fishing or reading...). but with the loads chart you provided i will be able to formulate a fairly accurate survey of my electrical needs.

now, i just have to figure out where im going to mount the solar panels LOL 180+ watts of solar array will take up some serious space!!

how well would it work to build a split solar/wind turbine electrical system? would i run into a ton of problems feeding both of the incoming power lines into the same controller system?

just trying to think of ways to maximize the space at hand... looks like im going to need a little more juice than i first expected.

also... this may be a stupid question, but... i have a 12v 2 hour charger for my Nickle type rechargeable batteries (many sizes, AA, AAA, etc.). Its load is rated as "Input: 12v 500mA". My radio and tv run on these rechargeables for MANY MANY hours before needing to recharge (Ive never replaced the 4-AA in the am/fm radio, and listened to it for probably over 100 hours, cant recall the tv battery life offhand tho). Wouldn't it seem logical to recharge the batteries thru my 12v system on the boat, then operate those 2 items on the rechargeables instead of keeping them plugged into the boat electrical system?? i know power from here is just being used there... so, thats why it may be a stupid question but im asking anyhow, it seems like it would use substantially less electric load to just recharge the small batteries than it would to run the electronic devices based on the load chart provided...

again, thank you very much for your detailed reply.
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Old 13-10-2007, 10:11   #5
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I think there are some excel spread sheets around to work out your amp hr usage and then develop a strategy to meet them... by batt capacity and charging sources.

A little knowledge is...

sv shiva
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Old 13-10-2007, 11:14   #6
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You have much more mounting space than you think. Look at Boat Mounting Kits for Solar Panels for some ideas and Compare all brands Solar panels at the Lowest Prices. Low prices on all solar power components. Let us design your solar energy project. , Kyocera Solar Panels , and/or Sunwize SW85 85W 12V Solar Panel for sizes and prices of solar panels. This will give you a place to start.
You will also need at least two 6 volt golf cart batteries (higher storage capacity) to get the system going.

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Old 13-10-2007, 21:57   #7
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Checkout this web site. They have some useful information and tools for dimensioning your solar system.
Systems Sizing and Design.


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