Small solar solution?

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I keep seeing references to 100 watt panels in the replies. My thought, since I only have room for 1 60 cell panel, is to get a high quality panel in the 275-300 watt range. Combine this with a good MPPT controller.

Am I missing something?
 
dhays said:
I keep seeing references to 100 watt panels in the replies. My thought, since I only have room for 1 60 cell panel, is to get a high quality panel in the 275-300 watt range. Combine this with a good MPPT controller.

Am I missing something?
Click to expand...

Not missing anything. If the space and space configuration allows go for it..
Many of us have space and shape limitations. Sometimes the panels must be portable so physical size becomes important.

In some installs shading may be a real problem and two or more panels may do better than one larger panel.
But if shading is not then I suspect the single large panel will do better.
 
cardude01 said:
Do I need to disconnect for any reason? Will the solar controller sense that the AC battery charger is on and stop the current from getting through to the batteries from the solar panels?

I'm thinking of a setup with a 100w panel just used for topping off the batteries, or for backup if the shore power fails.
Click to expand...


No, a controller is not a watch dog and there is no reason for one. The chargers that I am familiar with do not allow user control of bulk, absorption and float voltages..........OK before someone jumps up and down........there are chargers that do, I am just not familiar with them.

From my experience, chargers that do not allow users to change settings, seem to always go to the lower sides. My Xantrex 5012 is always in a hurry to jump from bulk to float while the batteries should remain in float or at least absorption. Summary...so far... dock chargers do not charge lead acid batteries to their "full charge" but a solar controller at least those that allow users to change bulk, absorption and float voltages will.

I always leave my dock charger on along with my solar. My dock charger is a backup to a week of rain which might on a good day bring the batteries up to 70-80% while solar will bring them closer to 100%
 
C lectric said:
Not missing anything. If the space and space configuration allows go for it..
Many of us have space and shape limitations. Sometimes the panels must be portable so physical size becomes important.

In some installs shading may be a real problem and two or more panels may do better than one larger panel.
But if shading is not then I suspect the single large panel will do better.
Click to expand...

Yeah, I have room for one 60 cell panel. I suppose I could look for panels with smaller form factors and try to get two there, but one 60 cell panel will fit just about perfectly without my having to move other hardware out of the way.
 
Measured the boat the other day, and it appears I only have enough room for two 100W panels. Would a cheap package like this be good enough to keep the batteries topped off at the dock in case the shore power fails? I don't think 200 watts will do much for me out on the hook.
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/302025202826

I could go with a more expensive package like this with a better controller, but is it worth it with 200W?
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/281169784988
 
While I appreciate the convenience of a package, if you buy separate components you can put together a system at about the same price but with a superior Morningstar controller.

Buy whoever's 100 watt panels are the cheapest as they are all about the same. But buy this Morningstar controller- https://www.amazon.com/Morningstar-...&sr=8-18&keywords=pwm+solar+charge+controller. It may be Chinese made as they all are, but at least it is designed by Americans (like iPhones).

That more expensive package uses an MPPT controller and while it works ;-) it will add about 15% more to your batteries over a PWM controller like the Morningstar, but for 200 watts, it isn't worth it.

For easy wiring hook up your two panels with an MC4 Y and then use 8 gauge MC4 cables for the run to your controller which should be located near the batteries.

You might be surprised what 200 watts will do. It should put out 70 amp hours on a sunny day. That will just about cover me for a normal 24 hours on the hook. YMMV.

David
 
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cardude01 said:
Measured the boat the other day, and it appears I only have enough room for two 100W panels. Would a cheap package like this be good enough to keep the batteries topped off at the dock in case the shore power fails? I don't think 200 watts will do much for me out on the hook.
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/302025202826

I could go with a more expensive package like this with a better controller, but is it worth it with 200W?
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/281169784988
Click to expand...

When you say "you measured", that gives you a footprint of the physical dimensions or real estate you have to mount panels. I am sure you should be able to find panels that fit in that footprint that have different watts outputs greater than 100W. Personally, I would get that highest output panels I could get to fill that footprint. Also get the highest voltage panels you can get and let the MPPT controller convert that to a higher amps input to your batteries. Higher volts and watts per square inch of panel and an MPPT controller will cost more but you will get more bang out of the real estate you have available.
 
Oh yeah. I mean I measured for those panels in that package that were like 27x47". Didn't realize I could get bigger power panels in that same size.
 
cardude01 said:
Measured the boat the other day, and it appears I only have enough room for two 100W panels. Would a cheap package like this be good enough to keep the batteries topped off at the dock in case the shore power fails? I don't think 200 watts will do much for me out on the hook.
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/302025202826

I could go with a more expensive package like this with a better controller, but is it worth it with 200W?
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/281169784988
Click to expand...

I don't know what your exact needs are when out on the hook but 200 watts is nothing to sneeze at. 200 watts will give you over 50ah on a decent day. I have only a single 100watt panel and even at 25ah per day, its enough to reduce my generator needs when on the hook and assures my banks are properly topped off when I'm not there without having to run the generator for hours before I can leave the boat for the week.

Ken
 
cardude01 said:
Oh yeah. I mean I measured for those panels in that package that were like 27x47". Didn't realize I could get bigger power panels in that same size.
Click to expand...

Good suggestions above! Here are a couple of more.

IF and only IF you go with MPPT, consider higher panel voltages to minimize wire losses which will force the use of large wire sizes. The upper voltage that you select should be determined by what the controller will safely accept. And of course, maximize the wattage that will fit into your available real estate.

There is much conjecture pertaining to operating panels in series. My experience with my 32vmp panels in series fails to give proof that shadows are panel killers but my participation in that discussion is behind me. I recommend considering using series wiring to allow easier, less expensive installation.

Next has to do with panel mounting. I have seen pictures of nice jobs using clips. I avoided clips. My panels are mounted on top of two hardtops that of course have curvature. I secured my panels with silicon caulking the ONLY place that I can recommend silicon usage on boats. Again, in my case, the panels are out of sight and adhesives worked and also eliminated any need to drill holes for clips. To accommodate for the curved surface, I installed a narrow strip of plastic wood under one edge of each panel. The stuff is sold by the big box stores and you can cut them to the sizes you require. This provided an air space between the panels and the mounting surface.

I don't recommend using 5200 unless those panels are going to be there forever........remember, even solar panels have a limited life. Before increasing my panel wattage, the 145 watt panels I used were secured with 5200. What a $%^&**&^% job it was to remove them.

And good luck......plan to get this done before foreign panels are slapped with high tariffs.
 
Last edited:
djmarchand said:
While I appreciate the convenience of a package, if you buy separate components you can put together a system at about the same price but with a superior Morningstar controller.

Buy whoever's 100 watt panels are the cheapest as they are all about the same. But buy this Morningstar controller- https://www.amazon.com/Morningstar-...&sr=8-18&keywords=pwm+solar+charge+controller. It may be Chinese made as they all are, but at least it is designed by Americans (like iPhones).

That more expensive package uses an MPPT controller and while it works ;-) it will add about 15% more to your batteries over a PWM controller like the Morningstar, but for 200 watts, it isn't worth it.

For easy wiring hook up your two panels with an MC4 Y and then use 8 gauge MC4 cables for the run to your controller which should be located near the batteries.

You might be surprised what 200 watts will do. It should put out 70 amp hours on a sunny day. That will just about cover me for a normal 24 hours on the hook. YMMV.

David
Click to expand...



David,

Thanks. I just know so little about this stuff I thought a package deal would be easier. But if the controllers in the packages are junk then I guess it's a dumb idea.

Are those Renogy panels any good?
 
Last edited:
cardude01 said:
Thanks for all the solar info.

Another (probably dumb) question. If I'm plugged in at the dock with the battery charger on, can I also leave the solar "on" to save my batteries in case the dock loses power, cord fails, etc?
Click to expand...

Yes.
 
cardude01 said:
Do I need to disconnect for any reason? Will the solar controller sense that the AC battery charger is on and stop the current from getting through to the batteries from the solar panels?

I'm thinking of a setup with a 100w panel just used for topping off the batteries, or for backup if the shore power fails.
Click to expand...


Yes there is normally no need to disconnect, if you do, make sure you disconnect the panels before you disconnect the controller from the batteries.

Ken
 
kchace said:
I don't know what your exact needs are when out on the hook but 200 watts is nothing to sneeze at. 200 watts will give you over 50ah on a decent day. I have only a single 100watt panel and even at 25ah per day, its enough to reduce my generator needs when on the hook and assures my banks are properly topped off when I'm not there without having to run the generator for hours before I can leave the boat for the week.



Ken
Click to expand...


I have two Frigoboat units (one set up as a fridge and one as a freezer). Don't know the exact draw but they are supposed to be pretty efficient with the keel cooling and Danfoss compressors I think. Those fridges are my biggest need and draw on the hook. My lights are all LED.
 
foggysail said:
Good suggestions above! Here are a couple of more.

IF and only IF you go with MPPT, consider higher panel voltages to minimize wire losses which will force the use of large wire sizes. The upper voltage that you select should be determined by what the controller will safely accept. And of course, maximize the wattage that will fit into your available real estate.

There is much conjecture pertaining to operating panels in series. My experience with my 32vmp panels in series fails to give proof that shadows are panel killers but my participation in that discussion is behind me. I recommend considering using series wiring to allow easier, less expensive installation.

Next has to do with panel mounting. I have seen pictures of nice jobs using clips. I avoided clips. My panels are mounted on top of two hardtops that of course have curvature. I secured my panels with silicon caulking the ONLY place that I can recommend silicon usage on boats. Again, in my case, the panels are out of sight and adhesives worked and also eliminated any need to drill holes for clips. To accommodate for the curved surface, I installed a narrow strip of plastic wood under one edge of each panel. The stuff is sold by the big box stores and you can cut them to the sizes you require. This provided an air space between the panels and the mounting surface.

I don't recommend using 5200 unless those panels are going to be there forever........remember, even solar panels have a limited life. Before increasing my panel wattage, the 145 watt panels I used were secured with 5200. What a $%^&**&^% job it was to remove them.

And good luck......plan to get this done before foreign panels are slapped with high tariffs.
Click to expand...


Thanks for the reply. I see the package deal I found comes with clips, but I would hate to drill that many holes in the PH roof. So the silicone holds up pretty well? Would a hurricane blow them off? I'm a hurricane magnet. [emoji23]
 
cardude01 said:
David,

Are those Renogy panels any good?
Click to expand...

I have a 100 watt Renogy panel that I installed on my boat for exactly the same purpose as you: keeping the batteries topped up- at a mooring. It has been going strong for three years with a Morningstar controller. But find the cheapest as they are all about the same.

Here is a link to an article I wrote for an RV forum that gives more details on how to do it: Aluminum Camper Forum Newsletter.

Read Merlin's electrical primer that follows my article and you will be an expert ;-).

David
 
If you can`t squeeze in more panel, go with the 200w, it will be worthwhile. I have only about that,I don`t leave the boat on shorepower, batts are always full, and it is enough to feed a Danfoss powered fridge during the day with a bit left over.
My panels are screwed to teak strips sikaflexed to the FB deck. Does no violence to the deck and the adhesive/sealant takes up any unevenness so the panels are not stressed.
Assuming you have a genset, give its start battery a small panel of its own.
 
Last edited:
Before I re-skinned my pilothouse roof, I had two 84 Watt Kyrocera panels that kept my twin 8-D’s topped off nicely, although this was in FL the entire time. At anchor in the Exumas, the previous owner kept the refer on propane and ran pretty much everything but A/C and hot water without Gen time.
 
cardude01 said:
Thanks for the reply. I see the package deal I found comes with clips, but I would hate to drill that many holes in the PH roof. So the silicone holds up pretty well? Would a hurricane blow them off? I'm a hurricane magnet. [emoji23]
Click to expand...

No clue to hurricanes but a hurricane is sure to cause damages to many things. This I do know, I could not budge lifting/ripping off one of my earlier panels held with 5200. So if you have concerns......5200. But you cannot have it both ways. With 5200 securing a panel it will require days to remove it in the future.

Because I secured my panels with each longer edge with silicon, I would place greater trust in that than puny clips
 
Try mounting the clips to the hardtop with 4200 or 5200, then mount the panel and/or panel frame to the clips with bolts or other fasteners that are removable.

Silicone is made for sealing and is fairly low on adhesion strength. I‎t will likely work but I wouldn’t trust it. Like many, I avoid the stuff when at all possible for other reasons.

5200 is removable by cutting i‎t away. Keep the pad/bracket area fairly small and you can get a blade under it to cut it away. 4200 is a lower strength version (still stronger than silicone) that would be less work to remove. Either way, you can change panels in the future and still use the same pads/brackets. I agree that it would be a mistake to adhere the whole panel with 5200; way too hard to remove.
 
Great ideas. Thanks.
 
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