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Unclematt

Senior Member
Joined
Apr 9, 2020
Messages
318
Location
United States
Vessel Name
Seaview
Vessel Make
Sundowner 32
I have searched the forum without finding what I need to know. I want to add solar to my boat what do I need to know as far as hook up and monitoring. I have a 6' x 6' roof top area which should be more than I need. I talked to a guy from Marine Solar and he said just install and hook up to the batteries. That seems way to simple. My boat was completely rewired and upgraded in 2021. It is redone to 2021 standards. My house bank is 6 volt AGM with 800 amp hours (400 at 12 volts) I need your guidance as I know very little about it. The guy that did my all work is booked out and thinks I can do it
myself. Please advise. TY
 
If you were to use Victron solar controllers (which I would highly recommend) you can get them with Bluetooth and use their free app to monitor.

Ken
 
Well, from an electrical hookup perspective, it's close to just wire it into your batteries. Biggest difference is there needs to be some sort of controller between the panels and the batteries to modulate the flow. These days, often called an "MPPT" type controller. Victron is the most common on this forum, but there are others. Very basic schematic attached.

By far, the most difficult part of the install is not the wiring, but the physical mounting of the panels. You will need to find panels that fit into your roof (hard top? A picture would help) including some mechanism to fasten them down.

I installed a pair of Newpowa panels on my camper van that seems to work fine. They now have 220w panels (24v) that look like a good starting point depending on your mounting constraints (HERE). Panels with more capacity would be better of course, but these would definitely help. At 24v, they would allow you to use smaller diameter cables, especially if you ran them in series.

I assume you would mount two panels - if they are both on the same plane (meaning one isn't skewed in a different direction than the other which happens sometimes on arched cabin tops), and I'd there are no shading issues, you can use a single controller. A suggestion is something like this Victron 100/30 (HERE) would work and give you some headroom for future larger panels.

Suggest next step would be to do a bit of Google searching for panels for physical size, and giving some thought on how to secure them to your roof. Don't worry too much about the voltage - they don't necessarily need to be categorized as yacht or RV (usually 12 volt). Once you have an idea of how you'll mount and the size, folks here can assist with putting the assembly together. Wire size, making sure the MPPT is properly sized, etc. it is pretty straightforward but there are a couple things to be aware of.

Good luck.

Peter
 

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Unclematt,I did mine some years ago,with no training in electrics. They worked.
You need to mount an inch above a flat surface to allow cooling.You can buy mounting brackets but I made brackets out of teak and aluminum angle, and attached the teak to the deck using Sikaflex polyurethane, to take up any unevenness and avoid stressing the panels and penetrating the deck. If you can mount the controllers where you can see them do, I had to put mine in the ER, not ideal for viewing or heat, but it was ok. You get a lot of information from a good controller. Some controllers have a monthly "equalization" option to prevent/fix sulfation, it`s a good idea but can be hard on batts.
 
If you have a battery monitor/amp hour counter, you’ll need to be sure to put the negative lead from the controllers on the proper side of the shunt. Otherwise the counter won’t see the solar input.
 
There are some electrical issues to consider, besides mounting considerations. Let’s assume you instal two, 24V, 200 watt panels. Wire these in parallel (+to+, -to-) and then use 8 gauge wire (to leave room for additional panels, otherwise 10 gauge) and wire to the controller input. You can do this with MC4 cables and MC4 “tees” for the parallel connections.

Wire the cable to a 30A minimum MPPT controller located as near to your batteries as possible and then wire the controller output to the batteries with 6 gauge wire with a 40A fuse near the batteries.

All of the panels, mounts, cable, fuse and controller are available on Amazon at the lowest prices anywhere.

So, the actual physical work of wiring isn’t difficult but wire and fuse selection requires some skill. You could probably resolve it all with a 15 minute conversation with your electrician.

David
 
...if they are both on the same plane (meaning one isn't skewed in a different direction than the other which happens sometimes on arched cabin tops), and I'd there are no shading issues, you can use a single controller.

Excellent point. Cabin tops almost all have some curvature. In a multiple panel application, is it better to mount the panels along that curve so that the sun angle is better on one than the other and have a charge controller for each panel, or better to mount the panels flat so that they all have the same sun angle and use one charge controller for the whole array?
 
Excellent point. Cabin tops almost all have some curvature. In a multiple panel application, is it better to mount the panels along that curve so that the sun angle is better on one than the other and have a charge controller for each panel, or better to mount the panels flat so that they all have the same sun angle and use one charge controller for the whole array?

six of one, i think. probably depends on potential shading issues. on my pilothouse roof, the panels are near the mast, so i had that to consider. i went with angling my panels slightly to each side and separate controllers. in some instances, i get full power from both, and other times i see full power from one, and almost nothing from the other, or some combination of that.
if i had a single controller, i seriously doubt that i'd harvest the same power as shading reduces the output pretty drastically.
 
Aesthetically speaking, my plan is to let the panels follow the arc of the pilothouse roof. That would mean 2 or 3 controllers. Is there a rule of thumb or some math to establish what how much arc is enough to need multiple controllers?
 

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Aesthetically speaking, my plan is to let the panels follow the arc of the pilothouse roof. That would mean 2 or 3 controllers. Is there a rule of thumb or some math to establish what how much arc is enough to need multiple controllers?

I was watching the Jeff Cote video and his comment was if you want the maximum from the panel all day long hold the panel in your hands perpendictular to the sun and follow its progress.
He was saying on a boat that will not happen so mounted it parrallel with the water is best.
 
Sorry I haven't gotten back. The storm was fairly intense today with a loss of power and internet. I have a flat roof with 6' x 6' for panels. I would make mounts and attach using thickso on G10 plates. It looks straight forward as to the wiring which was my main concern.
 
Aesthetically speaking, my plan is to let the panels follow the arc of the pilothouse roof. That would mean 2 or 3 controllers. Is there a rule of thumb or some math to establish what how much arc is enough to need multiple controllers?

That’s essentially what I did. I glassed in some backing so I could use extruded aluminum framing to mount the panels to. I don’t think there’s a rule of thumb for angle and controller count, but it is recommended to have some angle for shedding water. ( or so I read somewhere)
My panels are about 3 inches above the roof, and they’re almost invisible from the dock.
 
All good advice so far. I installed 52 panels on our barn three years ago, and all still working. This spring, we installed four panels on the boat. Two charge controllers (Victron) for amp limitations. The controllers are mounted in the ER, close to the batteries. The bluetooth connection is somewhat weak, so its not easy to monitor from the upper helm. But, I'm busy doing other things when up there...

A couple things.

1. Install circuit breakers for each charge controller between controller and battery tie.
2. When you install the panels, keep an air clearance beneath (as previously mentioned). However, keep in mind that the clearance makes the panel a wing, and although not perfectly designed as a wing, there will be uplift. So make your mounts sturdy on both sides (for down force and uplift). Heading through Jekyll Sound last week, we saw 30+ knots of wind on the bow. We were traveling a bit under 10 knots, and I could hear the wind whistling through the panels. They are all still there.
 
Panels are on my radar as well. Photos of installs would be much appreciated. My bridge enclosure is a rigid aluminum frame.
 
Here is a picture of during our install. Other pictures are even less flattering of us. Underneath the roof, I have large fender washers on each bolt.

We installed four panels, two each in series. The four wires (plus ground) are then routed down through the middle cross brace that runs forward to under the upper helm. (We got lucky there as there were four abandoned wires in the brace that I could use to pull things.) Where they exit the brace in the upper helm, I put in a disconnect switch (that handles both circuits), and then ran the wires back, down the chase, and eventually to the ER. Given the high voltage, I tried to keep things separate from the other DC wires "just in case."

I would provide pictures of the fender washers, disconnect, circuit breakers, etc., but we are now in Maine for the holidays and the boat is in St Augustine. Will go back in a week.
 

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Always find my typos after I submit. The "found" panels should be "four" panels.
 
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Your guy from Marine Solar is right. It really is simple to do yourself. Hiding the wires takes time. Here are some mounting pictures that may help.
This is a link for solar kits. Canadian company but good information. https://www.solacity.com/product-category/kits/
 

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Great info thanks. Should each panel have a controller? My roof will fit two with ease. Thanks
 
Different schools of thought here.
I say one controller for as many panels as a controller can handle.
Others go for redundancy
 
I think a main benefit from multiple controllers is to mitigate the effects of shading. If one panel is shaded and it’s in series with others, there is a greater loss. If 2 controllers, the panel(s) with no shade will still provide their full output.

Ken
 
I have two panels and one controller. The panels are hooked up in a daisy chain style. The wires have male / female plugs to no chance of error in hook up. see picture. Tons of information on the WEB.
 

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Great info thanks. Should each panel have a controller? My roof will fit two with ease. Thanks

As mentioned, shading issues will be the biggest reason to go with separate controllers. It looks like you’ve got a mast that will likely shade one panel in many situations. I have a very similar rooftop setup and it’s surprising how such a small amount of shade will reduce output.
I went with two controllers for two panels, no regrets.
 
I never really understood the two panel - two controller concept. If one panel is shaded and the other in the sun how does the controller and battery know the difference? I have found that solar panels bring in more power than needed and my single controller ends up dumping power. (said by a user, not an engineer):blush:
 
I never really understood the two panel - two controller concept. If one panel is shaded and the other in the sun how does the controller and battery know the difference? I have found that solar panels bring in more power than needed and my single controller ends up dumping power. (said by a user, not an engineer):blush:

Also a user vs an engineer, but my understanding is shading has a disproportionate effect. A panel with 10% shading will reduce output by much more than 10%. However, I have never seen anything empirical demonstrating or explaining this. So it's a good general question. Maybe someone with deep knowledge can give more than passed-along impressions.

Peter.
 
Your guy from Marine Solar is right. It really is simple to do yourself. Hiding the wires takes time. Here are some mounting pictures that may help.
This is a link for solar kits. Canadian company but good information. https://www.solacity.com/product-category/kits/

I like the hinges. Do you lift them up to clean under? Mine get pretty gross underneath.
 
The decision to go with two controllers in my case was partly due to the wire available without having to tear into the wire way.
If you’re putting in multiple panels, and shading may be an issue, you have to decide how to arrange the system. Series connections will raise the voltage, but amps remain low, so the wire size is smaller. But, If you have series connections, and there’s shading on one panel, it reduces the output of the entire string to whatever the reduced power panel puts out.
So, you can wire parallel instead. Voltage remains the same, but amps double. Bigger wire size is needed, as well as larger controller, which is likely more expensive. The effects of shading on parallel connected panels is much less than series as the voltage remains the same and the amp output is simply added.
The third option is separate controllers for each panel. This lets the controller optimize the output for each panel. You can use less expensive controllers and smaller wire.
Here’s a good explanation of the effects of shading. https://energyconnections.net.au/pa...e is shade on,sourced from Clever Solar Power.
 
Here are some mounting pictures that may help.

Slick install, Barrie. I like those pinned mounts. Would you use them again on your next project? Where do your wires enter the pilothouse and where do they get into the engine room?
 
Slick install, Barrie. I like those pinned mounts. Would you use them again on your next project? Where do your wires enter the pilothouse and where do they get into the engine room?

Those are actually hatch hinges, commonly used on older sailboats with wood forward skylight hatches. It seems you could unpin one side and then hinge up to clean the deck underneath. Mine are bolted down so it's a major deal to clean under.
 
Whoa!!! here it is Christmas eve and we got a good group of boaters talking about solar panels. The wife's presents must be bought already.
Bmarler: I checked out the link you sent about shading. If I lived in a stationary house with a problem with trees I would agree with their scenario. However, boats swing in anchors. While traveling your not always going in a straight line, and when tied up at a dock you have the option of turning the boat around so it is in the sun or just plug it in. I get shading from my canopy at the dock if I don't move, but by the end of the day I am so fully charged shade is not an issue when the sun goes down.

Headed to Texas; yes this system works well. Allows me to unhook the other end and lift for cleaning. Only clean every two years. The hinges are from Victory. I just checked the price and can't believe the increase in two years. Good system.
On the deck I used Blue sea Cable clams. Silicone tight. Drilling the first hold in the deck is neve racking but after that its "I don't give a shxxt attitude. This job is going to happen". There is always a channel somewhere onboard to run the wires down to the battery area.
I hope this help. Holler if you need more help.
Barrie
Merry Christmas
 

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