Small solar solution?

Did a quick search but didn't really find anything...

When I say "small solar" I'm talking about both space and output. I have an empty 4'x3' (or so) space on top of the pilothouse and would like to mount a simple solar panel setup. Basically just something to keep the batteries topped up so I don't have to worry about shorepower going out at the dock, and if on the hook maybe enough power keep up with one (or two?) of my fridges/freezers that are each powered by a keel cooled Danfoss compressor that allegedly uses about 6 amps to run, and runs about 50% of the time.

I'm an electrical idiot so I have no idea if this is possible.

Is there a "kit" that comes packaged with a controller, wires, etc or do I have to buy things piecemeal?

Piecemeal, however a solar seller will put a package together for you with tracks, mounts, cables, connectors, controller and breakers. Much easier than getting things bit-by-bit yourself. If you can, spec a one-size larger cable than you think you need for voltage drop and future expansion (this stuff gets better day-by-day). MPPT controller and mono crystalline panels to get the most out of a small space. It might even be worth your while to raise the panels a but and have them lap over the area you've got to add some capacity. I settled for 600 watts but you will likely just have room for 300. My batteries are in float by noon in the summer but I have light loads and I have no idea how the system will fare in the winter here.

My 300 watt panels are 3' by 5'. I would give a lot of thought to mounting your panels on the rails and make them swivel to the vertical when they are not in use. One on each side, two controllers. Then while you are docked, the one away from the dock could be up. At anchor, both up. 3 x 4 is very small and probably won't keep up with a fridge and a freezer. However, your latitude is a lot lower than mine so you have a longer day to collect the rays.

Ok. Thanks for the info. Where is the best place to start shopping and researching prices?

I hope Fast Fred sees this thread and leaves his links here. My phone crapped out that had the solar links.

Cardude, I am thinking of the same thing for this next year. I have room on the top of my PH for a 60 cell solar panel. I'm thinking one high quality panel along with a MMPT controller. Making that all work together with mounting and wiring is the issue.

cardude01 said:

Ok. Thanks for the info. Where is the best place to start shopping and researching prices?

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Ebay. My panels and regulators acquired from an ebay seller are still going fine after 7 years.

These is a basic outline in the following thread:

Transformation Continues

Solar update:





The system performs far beyond our expectations. One of the best choices we have made on Ebbtide. Making ice on the hook in silence is amazing. We actually have a surplus unless the blender and ice maker are running at the same time. Good times!

http://www.trawlerforum.com/forums/showthread.php?p=563765

Sounds like a 75W or 100W solar is all that will fit.

Real EZ to keep the batts up, but will be really pressed to do a fridge / freezer.

Fingers crossed but probably not.

I have use a Trace C 12 for years as charge controller.

These are great as the charge voltage can be changed easily.

A bit higher when aboard cruising , a bunch lower when sitting 6 months , to use less water.

Fred, thanks.

Is something like this "package" worthwhile, or junk?

I probably don't have room for both those 100w panels. Need to measure.

https://www.renogy.com/renogy-200-watt-12-volt-solar-starter-kit-w-mppt-charge-controller/

You need to know the space you have available. If you cannot fit two 100W panels then maybe you can fit two 85 W panels. But you must know that space, then decide.

I have a similar problem, a small area I can use. Would love two 135W panels. Not going going to happen but I can fit two 100W panels.

It will not run my boat ,fridge and freezer, but will give me one or two more days before we have to attend to other problems.

I have not done it yet but unless my idea blows up in my face it will come for next summer.
I will use an Mppt controller to get the most power out of the panels even though strictly speaking my intended array would not warrant the extra cost, I,m told.

I won,t use a cheapie Mppt unit. From reviews the quality may be questionable. Not blowing up but although they are called Mppt they do not actually perform as such but more like a pwm unit.

Details, details. But even so any decent array will help.

I have two friends who have approx. 250w total, either two or in one case 3 fridges/freezers
and as long as the sun shows 50% of the days they are good untill the ho?ding tank dictates move time.

Even only 2 x 85w panels should help a lot.

There are good articles explain the difference between. Mppt and Pwm units.
Arizona Solar among others.

All:

I'd like to prewire my boat for solar. I.e. run wires from the flybridge hardtop to my charger/inverters. Must one know exactly what all the components are in order to spec the wire(s)? I could definitely say how much sq. footage I can allocate, and I know what kind of charger/inverters I will have.

Is it possible at this point in time to say "for NNN square footage, and a run of NN length, you should use NN AWG wires?"

Should be possible but one must have made most of the equipment decisions first.
Should you later wish to alter something you may be limited.
Panel wattages, panel output voltages (series or parallel connections) mounting locations for panels and controller, fusing or circuit breakers, controller size and type , Vdrop allowance, should all be closely known.

Even then once sizing is determined I would go up a size to allow for some minor changes. Also do not cut wire to closely to length or you may find wire to short if something does need to be changed. If the final installation is too far out you may find equipment changes force some installation changes.

But yes, if all is WELL planned, it will be possible.

Shipping is expensive , find a solar source you can pick up at.

Today $1.00 a watt is common , these seem expensive.

House panel mounts may not work on a boat.

Miami has good solar dealers , would be worth a taxi tide 2 ways.

Only purchase panels from a company that has been in business for years , or you could get Solindra , a long gone or soon gone label.

You can fit one 100 watt panel in that area. Monocrystaline panels are more efficient (i.e. smaller area for a given output), but for a 3 x 4 foot space a the form factor on a polycrystalline panel might be a better choice.

You can order a panel from Amazon and get free shipping. Here are a couple of suggestions.

100 watt poly panel - Amazon.com

100 watt mono panel - Amazon.com

slightly more expensive 100 watt mono panel - Amazon.com

You want an MPPT controller to get the most out of the panel. For a 100 watt panel all you need is a 10 amp controller. If you think you might want to add more panels in the future then a 20 amp controller would be worth the money. Here are a few suggestions:

Victron 10 amp MPPT controller - Amazon.com

(Victron products are high quality. This controller is pretty basic in that it doesn't have a display, but you can add an interface for more $).

Renogy 20 amp MPPT controller - Amazon.com

As far as the wiring goes, the kits likely don't have marine grade wiring (i.e. tinned wire), so just buy some wire and connectors. It is easy to wire a solar system (two wires from panel to controller and two wires from controller to batteries). The only tricky parts are actually running the wires and sizing the wires. Here is a video on wire sizing for solar installations.


This video is part of a multi-video series on solar power installation for RVs but everything in it applies to boats as well.

I also suggest that you install a 20 amp fuse between batteries and the controller and and on/off switch between the panel and the controller. A sinple 20 amp rated toggle switch will do.

A single 100 watt panel will NOT keep up with your refrigeration, but it will help and extend the life of your batteries.

Also, allow some space under the panel for cooling.

For you Canajuns, Andy at Topofthehill market in Powell River has extensive knowledge and the best prices on solar everything and batteries, his boast is "call me last." He has creative shipping methods too, talk to him. The package he sold me had a breaker box with a breaker for panel-to-controller and controller-to-batteries as well. I used aluminum racking and it works great. He supplied the cable too.

My MPPT controller is Outback, their head office is Arlington Washington and they have a 5 year warranty, 10 availabe. I did not do 10 because I think this technology is evolving rapidly.

I have a 2500 watt inverter that is currently (no pun) a battery charger powered by my genset, I plan to figure out how to wire it in to invert to use the excess solar power I produce to heat water. I intend to make a solar collector to heat water, to install on my roof, eventually. I have not used my genset once this year and during the summer, even with panels mounted flat, I am in float by noon each day.

The connectors are "coast rated" for salt environments and are intended to be used outside. I used dielectric grease in all connections too.

dhays said:

Cardude, I am thinking of the same thing for this next year. I have room on the top of my PH for a 60 cell solar panel. I'm thinking one high quality panel along with a MMPT controller. Making that all work together with mounting and wiring is the issue.

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Dave- I mounted four panels, two onto each of my hardtops without fasteners. My approach was to secure them using simple caulking, silicon this time. My prior panels were secured with 5200 and that was a lesson learned the hard way when I replaced them with higher wattage panels.

Both hardtops have curvature that I corrected by shimming one edge of each panel so the installation resulted in mostly flat arrays of panels. For shim stock I used plastic boards sold by big box stores that I cut to heights needed to correct the hardtops' curvature. The shim serves another purpose by creating an air space under the panels to enhance panel cooling.

Personally, I frown on using any mounting clips that require drilling. And I can attest to the caulking compound's holding characteristics. I have no fear of panels flying off in high winds.

Last year I installed a Renology 100w panel and I've been extremely happy with it. I really wish I could install more but unless I go with Bimini mounts, I just don't have the appropriate space.

100 watts will only get you about 25ah per day, where a fridge uss something like 75.

Ken

kchace said:

Last year I installed a Renology 100w panel and I've been extremely happy with it. I really wish I could install more but unless I go with Bimini mounts, I just don't have the appropriate space.

100 watts will only get you about 25ah per day, where a fridge uss something like 75.

Ken

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Agree. Yet that may be all many of us require, an extra day.
Some want to run the boat on solar, some only hope to lengthen a stay by a day or two.

This is how we mounted them on Ebbtide.

That's a nice install except I would have raised them to level and made a cooling space below them. I doubt if the small angle will compromise their efficiency but heat will. Is that 600 watts?

600w, so far no heat issues. Peak output 73v 9.5a...super efficient day.

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?

cardude01 said:

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?

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I leave my boat unconnected to shorepower, my modest solar array keeps the batts charged. I even have a panel serving the genset battery.
I encounter no issue I know of with 2 simultaneous charging sources. You already have that when the alternator is operating and the sun is shining. There was past discussion about "putting panels to sleep",eg,while working on the system. My solar systems have no "off switch", but you could disconnect a wire, or as I once did, cover the panels so the sun does not reach them.
I have had alternators running,panels connected,charger on, simultaneously,with no apparent ill effects. What the regulators think about it I`ve no idea.
Interested in posts about this, hoping to learn more about it too.

Look at E Marine Systems website. They are in Ft Lauderdale, you could pick it up on your way from the airport and save shipping (& damage). I have 480 watts and never turn it off, even when on shore power. The charge controller will take care of things.

Rafe

Ok. Thanks!

If you plan to connect or disconnect, do it at night or cover the panels. My panels have a warning sticker on them saying much the same.

Xsbank said:

If you plan to connect or disconnect, do it at night or cover the panels. My panels have a warning sticker on them saying much the same.

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I have thought that. But the Manual for my PWM controllers says that to adjust settings, remove all connections except the connection to the battery.
I`ve done it that way to make adjustments, all went well,with batts uncovered, so less sure about that warning .
Fairly sure this came up on another thread and it was said that once a connection to a battery was removed, generation stopped (think it was Brian/Insequent who is knowledgeable on panels). I also wondered where the amps went when the regulator finds the batts are full, as mine often are. The panels must still be generating, but I think Brian had the answer, and quoted someone authoritative.

Bruce-- What battery voltages are you charging with PWM controllers? Most likely your's are 12 or 24v which means the panel voltage you are exposed to is safe. But not all installations have safe voltages.

I installed a battery switch for my panels back when I used panels with Vmp of 18V for a PWM controller. Now however, my new installation panels have Vmp of 32V wired as two banks of series/parallel that provide voltages upwards to 70-75V to my controller. Anything greater than about 48V is dangerous and of course even lower voltages can do great harm it shorted out with a ring or a watch.

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.

No disconnect except for maintenance. Mine have breakers in and out. MPPT controller, the voltage is over 70.