Solar Question

JoeWhite · Dec 28, 2011

Yes to Blocking diodes. The idea is that the current produced form one panel does not enter the next solar panel as one solar panel may have a higher voltage than the other. Addition a blocking diode also reduces the output voltage of each solar panel by 0.5V. But this is OK - since solar panels normally produce about 16 V DC.

Ray Bowles · Dec 28, 2011

Aren't you going to be pushing the upper limit of your regulator. We used a 30 amp for the same load of panels based on what the marine electrician told us. Just my 2 cents.
Ray

Capn Dave · Dec 29, 2011

Not really

JoeWhite said:
Yes to Blocking diodes. The idea is that the current produced form one panel does not enter the next solar panel as one solar panel may have a higher voltage than the other. Addition a blocking diode also reduces the output voltage of each solar panel by 0.5V. But this is OK - since solar panels normally produce about 16 V DC.

Joe: what you are talking about are bypass diodes. By-pass diodes will not be of use unless panels are connected in series to produce a higher voltage. Which do exactly as you say, but the curciut is completely different .
What Ray asked, is about blocking diodes, which keep the batteries from discharging, back into the solar cells at night.

Bill Roosa · Dec 29, 2011

if all the power will be going through the regulator and the regulator has a blocking feature then you do not need blocking diodes on your new panels. You can take them off your old panels and have 0.5 more volts or a "massive" 1 watt increase in power output.... probably not worth it.
Another thing to consider, if your flexable panels put out 16 volts and your new rigid panels put out 18 volts and you connect them in a parallel fashion will not the rigids overpower the flexables. This is similar to using different battery types together. if the voltages don't match then you get problems. Perhaps your regulator can handle two different types of panels. If that is the case then you would want to keep likes together. In any case if the blocking diodes on the flexables sees a voltage greater then the forward voltage from its panel it will just shut down its panel. 0 output.
Also 4*50+3*22=266 watts of panels. that is 266/14.4=18.5 amps!!!! and you are buying a 15 amp regulator???????

Maine Sail · Dec 29, 2011

Rick,

Are you asking about "blocking diodes" or "by-pass" diodes. Most decent quality panels should already have by-pass diodes installed. I would check with your panel manufacturer. You do not need a "blocking diode" as your regulator will prevent back drain of your bank at night and will have that feature already built in...

Bill Roosa · Dec 29, 2011

Panel configuration

A closer read suggest we have some confusion as to how you are going to wire the panels together. I assumed you would not be putting any of the panels in series with other panels.
You mention 3-22 watt panels but I'm thinking you are only putting the four new ones on the regualtor?
This is what I think you are describing.

Sumner · Dec 29, 2011

Rick D said:
...first, thaks for all your help. I am planning on running two of each of the 50 watt panels in parallel and then to the 15 amp regulator which will then see the panels as two 100 watt. I am planning on leaving the regulator for the three 22 watt panels in place and regulating the 50 amp panels separately as Bill noted....

If I'm reading the above correctly I think you are making things more complicated than needed.

We have 3 panels on the Mac, a 40,60 and 100. They are all the same type panels and operate with the same voltages. They are all wired ....

.... to a common terminal strip (shown above without the panel wiring that is attached at the top). The terminal strip is under the panels in the lazarette. Then there is a pos./neg. wire from the terminal strip going forward to the ...

....Blue Sky MPPT controller (bottom right arrow). For the controller to be most efficient the panels should be of similar construction and operating voltages. Also size the wiring for minimal voltage drop to take full advantage of the panels.

The terminal strip allows us to remove any or all panels pretty quickly. Be sure and read the charge controller instructions on disconnecting panels to make sure you don't damage anything. I have a switch that disconnects the charge controller from both the ship's batteries and the panels at the same time.

I have more info on mounting the panels and the wiring on this page....

http://purplesagetradingpost.com/sumner/macgregor2/outside-33.html

Good luck,

Sum

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Maine Sail · Dec 29, 2011

Rick D said:
...first, thaks for all your help. I am planning on running two of each of the 50 watt panels in parallel and then to the 15 amp regulator which will then see the panels as two 100 watt. I am planning on leaving the regulator for the three 22 watt panels in place and regulating the 50 amp panels separately as Bill noted.

The reason for all this is that the three 22 watt panels sit on my bimini and are never used underway. The 50 watt panels will hang on the rails I used to replace my aft upper lifelines. The reason I did not simply go with two 100 watt panels is that I need to store them in my dock box and the 50 watt panels will do the trick. I only want them when cruising, not day sailing or racing.

So, I was referring to blocking diodes, not pass through diodes. I am double checking myself to be sure there isn't a problem somewhere along the line with what I propose. There are good resources on these boards, so I figured I should take advantage of them.

Rick,

Two charger controllers together can do battle with each other and panels of differing voltages should ideally not be used together on one controller or you can bring the performance down to the lowest common denominator.. When in bulk mode it won't matter one iota if you have two controllers and both sets of panels can pump in the most thay can get from the sun. This is because neither controller is the "voltage limiting" phase at that point.

The alt however can usually get you back to absorption voltage then the controllers and solar need to take over to get you back to 100% SOC. The problems can occur when you're in absorption charging and things can get quirky between multiple charge sources..

It would be extremely rare that both controllers were set to regulate to the same exact voltage and as such the one with the highest voltage setting will win. The other controller will likely just shut down, if a shunting type, as it is seeing the bank voltage is above its absorption voltage set point. In some cases the second controller will never turn back on unless you take the other controller with the higher voltage off line or drop the bank back into bulk mode where the controllers can't reach 14.4V or what ever they are set to. With two controllers you'd want the one for the 200W of panels to have the higher absorption voltage so you don't give up their performance..

I had a customer this summer who was getting horrible output from his two 80W panels. About half or less than what he should have been getting, or thought he should be getting. He bought them as a kit and each panel came with a controller so he wired them both into the system. Both controllers were identical models and brand. Still, one controller was set about 0.06V higher than the other for absorption voltage and the other one simply shut down or "shunted" because it sensed that the system was over its regulation voltage. The result was that it took considerably longer to charge his bank than it should have.

I wound up replacing both shunting controllers, as neither controller could handle both of the 80W panels together, with one Morningstar ProStar 15 PWM regulator and he was fine. Lucky for him both panels were identical and thus no differing panel voltage issues. I cut his time to "full charge", from where the alt left off, by days just by putting both panels on that one controller.

With your panels you're a good candidate for an MPPT controller but be sure to look at controllers that allow you to adjust the voltage up beyond the controller for the flexible panels.

Trey0056 · Dec 29, 2011

Not sure how many battery banks you plan on charging but might want to consider splitting the panels and running them through two regulators to two different banks. Its how I did mine after being frustrated by the controllers charging one bank on float while another bank was dead.

Sumner · Dec 31, 2011

Rick D said:
...Any more suggestions before I pull the trigger are welcome...

I agree with you that with 200 watts you will be about half of your use. With 180 we were able to keep up with over 90% with one frig and using the computer quite a bit and a few other things.

Which controller are you thinking of getting? MS had a good suggestion about going with a MPPT controller. We have one on the Mac and bought this one....

http://www.solarblvd.com/Charge-Con...AR-BOOST-3024iL-30A,-12/24V/product_info.html

...for the Endeavour. It is just big enough for the six 80 watt panels going on it. I ran the panels and such by the Blue Sky tech guy and he agreed that it would work, but it will be maxed out panel wise. The MPPT controllers are more expensive, but they will give you the most out of your panels.

Good luck and you will love the solar, we do,

Sum

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Trey0056 · Jan 1, 2012

Sounds like a plan. Just remember to rig a switch in case you want to turn off the solar panels to bank if you ever need to redo any battery wiring. so you are at two harbors? Im down at americas cup in sd.

Sumner · Jan 1, 2012

Rick D said:
Thanks, Sumner! I am looking at MPPT controllers. Seems silly to not get one. Also, the terminal strip looks like a good idea. What gauge wiring are you using for the Endeavor? I can figure it out but maybe you already have. Where are you fusing them?

I got some #4 in for the Endeavor that I'll take back with us. I'm hoping the run is under 24 feet. The #4 is good for that distance with a 3% drop at 30 amps. I have 480 watts potential and the 80 watt panels....

http://www.solarblvd.com/Solar-Pane...80-Watt-12-Volt-Solar-Panel/product_info.html

.... are rated at 4.65 amps working voltage and 5.17 amps short circuit so only 27.9 amps working and that would only be at max. sun angles and ideal temps.

For the 200 watts on the Mac I can't remember, but think it is 6 or 8. I also sized it .....

http://boatstuff.awardspace.com/awgcalc.html

...for the 3% or less drop.

There isn't much sense in fusing the lines from the panels to the controller as far as the panel output if the lines are sized right. With a PWM controller the line to the panels should be fused to protect them from possible battery current.

From what I read with a MPPT such as the one I'm using or maybe any of them the controller will limit amperage from the direction of the battery to the panels. The one area they do recommend protection is to each individual panel in an array. If one panel shorts out then it could receive the amperage from the rest of the array. I don't have fuses on the panels on the Mac and I'm not sure at this point if I'm going to fuse them on the Endeavour, but might seriously think about it as the array has a much higher amperage potential. I'm not sure how likely a panel fire would be so will have to think about that.

If I do fuse the panels I might...

...put a spade fuse holder on the end of each panel's #14 wire and they will go to a common 5/16 inch post terminal I bought and the #4 line to the controller will also go to that post. The negatives will be the same, but without the fuses. Not to elegant, but simple and fairly cheap and something that will make it pretty easy to detach panels. After breaking a panel on our last trip, my fault, seems pilings are stronger than panels :cry:, we bought a spare.

At the end of our trip when the Endeavour goes back up on stands I'll probably remove some of the panels and store them below and keep a few in service to keep the batteries up.

Here is a link to what I believe is pretty solid info on fusing panels....

http://www.wind-sun.com/ForumVB/showthread.php?7020-Fusing-a-Solar-Panel

..but others might have other views. Looks like a MPPT controller also has some safety features in the way it also limits amperage in a circuit.

Good luck and solar in our opinion is definitely worth it and is getting cheaper,

Sum

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.

Captain Larry-DH · Jan 1, 2012

Was reading this thread with interest, as I've implemented and lived with several panel configs and different controllers. A few comments on prior posts:

1) Diodes. Most diodes will give -0.2 to -0.3 voltage drop. I've used several different types and never measured -0.5v drop. I suspect that might be a worst-case. I do recommend blocking diodes (not bypass) in your parallel panel config, because if one panel in a pair is partially shaded, or if an entire pair is on the shaded side of the boat the diode on the output of each panel will keep it from affecting the output of the other panels. Put your diodes (and fuses) at the terminal strip.

2) Fuses. You should have a fuse on the output of each panel, at the terminal strip. It only takes a fraction of an amp to cause a fire in thin wire, but even if you use heavy wire (e.g. 12 AWG) you have enough amperage in the array to cause a risk. It's a few bucks to add fuse holders and it can't hurt to put them in, but it might save your boat. There is no down-side to using fuses. I'd use a 4 or 5 amp fuse on a 50-watt panel.

3) Multiple controllers. MaineSail is right on target! I have experienced the same issue using multiple controllers. They aren't aware of each other and screw each other up so they can't accurately sense battery condition.

John Nantz · Jan 1, 2012

Rick D said:
My objective is to simply go from running my Honda 2000 from an hour and a half daily to every third day (except for hot water).

Any more suggestions before I pull the trigger are welcome.

With a little more sun as the days get longer you might be able to eliminate running the Honda for hot water too! There are replacement water heater elements that will work on either 12V and 120V, or 24V and 120V. I've been meaning to get one to replace our 120V element but haven't got around to it, maybe this year.

There is a place in Florida that specializes in alternative power for boats (solar and wind) but I couldn't find their URL just now. A search for "12V 120V hot water heater element" came up with this link: http://svhotwire.com/info/?p=78 They call it a "water heater load diverter".

For info, the combination of solar with a wind generator is really good. There are times when the sun doesn't shine that strong but there is good wind energy that can be captured, even at night. I've seen 25 amps from our little 1-meter 6-blade Rutland many times and that isn't shabby, especially at night! The two can complement each other.

Less engine use (main boat engine or Honda) ==> less wear and tear on the units and fewer trips to buy fuel. Also less hazardous explosive gasoline on board and fewer gasoline vapors escaping into the atmosphere. Much kinder for the environment.

Sumner · Jan 2, 2012

John Nantz said:
... I've seen 25 amps from our little 1-meter 6-blade Rutland many times and that isn't shabby, especially at night! The two can complement each other....

John we might like to add a wind charger at some point, but if we are mainly in the Florida area I wonder if the average wind speeds there will make it viable. You said 25 amps, did you mean 25 watts? Here is a link to the 913 ....

http://www.marlec.co.uk/wp-content/uploads/2008/09/913-data-sheet.pdf

....and I can't see where it could put out 25 amps. Do you have a different model?

Thanks,

Sum

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