SailNet Community banner
  • SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

solar panels

5K views 25 replies 9 participants last post by  johnnyboats 
#1 ·
im looking to have a 48v battery bank for an electric propultion system, besides having a generator for charging i want solar panels also. can solar panels be wired in series to multiply there voltage?
 
#4 ·
Johnny-

One panel will generally be 16-18 Volts... but the charge controller will step the amperage down and voltage up... To get any kind of real usable output for a 48 VDC panel, you'd probably need at least four 130 Watt panels at a bare minimum.
 
#8 ·
For trickle charging and topping up lets say you want a 5amp possible charge current at 48 volts this is about 250 watts total of panels. 2.5 amps would be 125watts of panels. What size will your battery bank be in amphours at 48volts? Note a 100amphour 12V battery gives you 25amphrs at 48vlts. That is the place to start.
 
#11 ·
I have 2 solar panels for a trickle charge but will be adding more instruments and now need to increase the size of my array. Can anyone make some brand recommendations based on personal experience?

Thanks
I have Kyoceras and other cruisers I know use them too without issues. They are well made and dependable. They come (at least mine did) with blocking diodes too.

Hope that helps.

- CD
 
#10 ·
Kyocera and Siemens are pretty good brands. I've used both, but neither in a marine situation...
 
#13 ·
Blocking diodes prevent the panels from draining the batteries at night. If there isn't enough light hitting the panels, they can actually drain electricity...
 
#14 ·
i dont know how to calculate the exact amperage of a 48v system, i know its would be beter to use 6v bateries, trojan makes a nice 300+ amp 6v, how much would that drop at 48v, and how much would it add up with 8 bateries in series? as for panels i figure i have room for 4 100+ watters, if there aprox. 50" long i could probably squeeze them onto my hardtop
 
#15 ·
Eight 6 volt 300a/h batteries is the equivilent of ONE 48V battery with 300a/h's. So...you would have 150a/h's at 48V to work with to get to 50% discharge and need re-charging.
Most 100W panels provide 17V output and approximately 5.9 amps so you would be providing about 24amps at 17V with 4 panels BEFORE regulation to 48V...and this works out to 2.2amps or so at 48 volts with a good regulator. Figuring 5 hours of peak equivilent sunlight a day and some conversion losses this would allow you to replace about 10amphours at 48V back into your batteries.
 
#17 ·
10 ah a day would be 15 days to fully recharge from a 50% drain with no other source of charge (mooring or no generator).

Powering a (48v) 30amp motor with 150ah of usable battery gives you 5 hours of run time, and if you are day sailing you'd need roughly a hour or less to just get out and sail (location dependent of course).

That 30ah for a day sail would be replaced in 3 days. Doing it twice on a weekend cruise plus minus overnight drain for house circuits (I run 40ah on average, but that's at 12v, you can call it an additional 10ah equivalent) and you'll be pretty much good to go week after week, if everyday is sunny enough to get you 10ah, 100% efficiency etc.

If the motor takes more than 30ah, adjust your throttle, run time etc.. and you'll be fine. Make sure you don't go short on system monitoring (meters).
Note normally I'm as anti-electric motor as it gets, for me this is a very positive post :)
 
#19 · (Edited)
Max current on the 48v Solidnav is 150 amp, at that rate there would be on one hour total run time at full throttle before cycling (damaging) the proposed battery bank.

As I said in my post, I was trying to be positive :)

SolidNav :: The first alternative for everyone

of course the controller is rated at 4kw, so the max you can get out of it is somewhere around 5.3hp, disregard the link's stated 24hp equivalent - that would be at 150amp x 48v, 7200 amp controller needed.

Gosh, reckon they are fudging the numbers a tad?
 
#20 ·
Chuckles-

Everyone knows that you can always trust a manufacturer's claims on their product completely. They'd never exaggerate or lie... would they???
 
#21 ·
I don't know SD, I tend to take them on faith when they say that an electric motor has full torque at 1 RPM, and it's torque that moves the propeller not HP and because of that the boat only needs 1/2 to 1/3 the horsepower when compared to a diesel.

That said, the chart at the link shows 65 amp's (3120 watts) or 4.1 hp pushing the Islander 28 test boat (7000 pound displacement) at 5kts. With 220ah of batteries on board..make that 8000 pound displacement.
Maybe they have something there, maybe not. I don't have an Islander 28 to test with a 4hp outboard.

Of course, real world independent testing has proven otherwise.

We'll purposely skip the fact that they say 3 hours of use to take the battery to 80% drained because no good skipper would KILL his batteries that way.

dang it, I was going to stay positive..
 
#22 ·
the electric drive system i would plan on using uses 40-60 amps cruising, about 150 at full throttle. i plan on having a generator producing 100 amps @ 48V, enough to keep up with any decent cruising speed, that would burn 1/5th gallon an hour, i would only run just electric for short periods, like entering harbors or docking, keeping the battery bank from draining any lower than 40% drained, greatly improving their lifspan.
 
#26 ·
thanks for the encouragement, yeah any kind of long range has to have a hybrid system. ive found two generators that produce 100 amps at 48v, one is at amplepower.com, the other is at re-e-power.com, i recomend checking the later site out if your curious about electric drives, this system is different but i think has the most pros for any system. ive still got a few months till my boat even leaves the dirt, so plenty of time for more research!!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top