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Old 01-13-2019, 10:19 AM   #1
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SOLAR, goods bads and options

Did a bid to searching for solar panels for the boat and there's a LOT of stuff out there!

Need some basics and recommendations.

Currently have four 6v AGMS which yield 440a at 12v, of which 220a is usable, not discharging below half.

Goal:
Be able to charge up the batteries after using them overnight, when they are down around 12.2 volts.
And charge them, while they are powering a fridge or two and some small stuff, perhaps 5a worth.
And just to maintain the batteries at the dock.

Would prefer a hard or semi hard panel. Looked at mounting to the Bimini top, a possibility, also considering a hard top, which should be fine. If not, some sort of railing mount, maybe something that swings up on the side.

Questions:
How much is enough?
How big are the panels for xxx power?
Can one recommend some good brands and companies to deal with?
Is monocrystaline the best material?
Will these things withstand the summer heat in FL, when I'm sure they will be north of 130d?

=====

Another wild question:
Is it possible to get 220v out of a solar array? I'm not able to get dock power to my boat for awhile, and it will be expensive... just wondering if some sort of 220v power is an option.
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Old 01-13-2019, 10:32 AM   #2
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Can't help you with the solar, but there are a number of manufacturers that make inverters that produce 220VAC from 12 VDC.

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Old 01-13-2019, 10:55 AM   #3
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..
Is it possible to get 220v out of a solar array? I'm not able to get dock power to my boat for awhile, and it will be expensive... just wondering if some sort of 220v power is an option.
Well, SURE you can make 220 out of a solar panel. FPL makes 238kV out of a few different solar farms in the state. BUT, you will need a battery system and an inverter. What purpose will the 220 serve?
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Old 01-13-2019, 12:08 PM   #4
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A couple of words of advice:

Use hard panels, not the semi flexible unless you want to replace them frequently.

Panels are rated at something like 77 deg, in Florida they will be way too hot to touch, and they produce significantly less when hot, so derate the output by perhaps 30% when doing your figures.

Most panels output drop to near nothing with even a thin line of shade across them. This means you want to mount them were they will be unshaded to the extent possible, and the use of many small ones in parallel rather than big ones will help mitigate the effect (because the shade only affects the panel shaded).

In Florida you can probably figure 5 hours a day of sun. That takes into account sub optimal aiming, cloudy days, etc. You are probably down 150 AH overnight, to recharge fully in 5 hours you'd need 30A output or about 400 watts. Except lead acid batteries don't work that way, the acceptance rate falls off rapidly when they get above about 80% SOC So you'll actually need maybe 50A output. Add to that the 10 or so amps you are presumably using (that caused the 150 AH use overnight), and the inefficiency of operating at high temps, you are up to needing maybe 800 watts. If not living aboard significantly less as they will catch up during the week, to what you used on the weekend.

The good news is that rigid panels are very cheap now. Bad news is you need to find space for them. 100W panels are about 46 x 15 give or take, around $100 each for good ones. Mono, poly, or amorphous cells all do the same job, but the mono will give the most power per unit area.

An alternative strategy is to run a genset or plug in for an hour each morning, this can do much of the bulk charging leaving the solar to finish off the long tail of the acceptance curve. You can get away with 1/2 or 1/3 of the solar that way.
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Old 01-13-2019, 12:29 PM   #5
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Quote:
Originally Posted by Seevee View Post
Did a bid to searching for solar panels for the boat and there's a LOT of stuff out there!

Need some basics and recommendations.

Currently have four 6v AGMS which yield 440a at 12v, of which 220a is usable, not discharging below half.

Goal:
Be able to charge up the batteries after using them overnight, when they are down around 12.2 volts.
And charge them, while they are powering a fridge or two and some small stuff, perhaps 5a worth.
And just to maintain the batteries at the dock.

Would prefer a hard or semi hard panel. Looked at mounting to the Bimini top, a possibility, also considering a hard top, which should be fine. If not, some sort of railing mount, maybe something that swings up on the side.

Questions:
How much is enough?
How big are the panels for xxx power?
Can one recommend some good brands and companies to deal with?
Is monocrystaline the best material?
Will these things withstand the summer heat in FL, when I'm sure they will be north of 130d?

=====

Another wild question:
Is it possible to get 220v out of a solar array? I'm not able to get dock power to my boat for awhile, and it will be expensive... just wondering if some sort of 220v power is an option.
I have 4 each 295 watt mono panels mounted onto my hard tops. Each has a 32 vmp and I have connect 2 in series in parallel with the other pair. So I am dealing with relatively high, unsafe voltages. There is an advantage to going to higher voltages because it allows getting by with small diameter wires from the panels to the controller. A disconnect switch SHOULD be used to isolate the panels from the controller because of the unsafe voltages produced by the panel arrangements.

Mono panels have a slight power density improvement over other options. So how many panels? I recommend install the maximum that space and $$$ will allow. Oh, my panels are Canadian, Google will provide more info pertaining to panel availability and prices. Personally I recommend staying with rigid panels AND allow air flow under the panels to help cooling.

Anybody installing a controller today other than one with MPPT features is wasting efficiency and MPPT’s cost today is affordable for most.

Why are you considering making 220V directly from panels? There are many reasons against that. The higher voltage will require caution to protect life AND panel outputs are DC, not AC. Another reason to consider a modern controller is that ALL solar panels are current sources, not voltage sources. That means they will try to output current regardless of the output voltage. Suggest that you look at panel output voltage/current curves.

Another important consideration to go with panels is having a decent battery bank to store the needed energy. Mine are rated at 880 amp hour at 12v made up of parallel and series connections using 8 each golf carts
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Old 01-13-2019, 12:48 PM   #6
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Quote:
Originally Posted by DDW View Post
A couple of words of advice:

Use hard panels, not the semi flexible unless you want to replace them frequently.


Most panels output drop to near nothing with even a thin line of shade across them. This means you want to mount them were they will be unshaded to the extent possible, and the use of many small ones in parallel rather than big ones will help mitigate the effect (because the shade only affects the panel shaded).
Shade causes output drop to near nothing??? That is a well spread myth. A panel will provide output when illuminated and there is illuminance present even in shade. Sure, there will be some output drop but not much from my personal experience. My panels have two pairs in series connected in parallel and I have NEVER seen my output current fall to zero when charging batteries when clouded or shaded. Shade will have an impact although nowhere near as much as claimed.

Yeah.....there are a few videos showing how a panel output drops to almost no output when a rag is place ontop of the solar panels. That is an unreal situation that completely prevents illuminance from getting to the collectors. Also there are individual diodes placed across the collectors so the output loss is minimized under shade.
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Old 01-13-2019, 12:56 PM   #7
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Hi Seevee,
I have solar panels (2 large rigid panels) on the roof of my pilothouse, installed last spring, so I only have experience with them of one summer. I also had solar on my previous boat, a sailboat where I had both rigid and flexible panels (one each).


We installed 2 fairly large panels on the Pilothouse roof of Pilitak (NT37) a year ago. The panels are monocyrstalline, solid aluminum framed with glass tops and are about 280 watts each (if I remember correctly – close anyway).
My suggestions for a solar install:
Put on the largest panels (total output) you can fit! More capacity is better in this case and the price difference in up sizing is not substantial when looking at the whole project.
Use MPPT type of controller, not the PWM type (especially for converting the unused voltage into useable amps). Some suggest using a separate controller for each panel which will maximize battery input when there is partial shading. I only used one Morning Star MPPT controller with a remote panel for “watching what is going on”. Use a quality brand controller (not the place to cut costs). Other good brands include: BlueSky, Outback, Genasun, etc.
Mount them in a location where shading from overhead items will be minimal and unless you are going to automate having the panels “point to the sun”, mount them basically flat, pointing straight up. In the Florida sun (hot), you want good air flow around them (under them as well) for optimal cooling. (As stated above by DW).

I installed mine so as to not penetrate the roof. Worried about future leaks. I attached stainless steel tubing to the existing hand rails above the pilothouse doors, to make a “mounting frame”. I then attached the panels to the tube “frames” using four (4) plastic adjustable “tube mounts”. I did the physical install myself, but did use a marine electrician for the electrical, but it was fairly straight forward for someone with some DIY electrical experience.
Anyway, I am happy with the total install after one season. Any day where the sun was out (not foggy) the solar restored my battery bank back to 100% each day by about 2PM (or earlier). I only ran the generator to make hot water (on a couple of occasions) and when we had heavy fog for a few days! We were out for over 3 months and put about 20 hours on the generator. Most of the time we were at anchor or docks with no power (say 70% of the time). We were out in over 30 knot winds, and did not have any problems with the mounting system.
Some background: we use golf cart 6v batteries totaling about 650 AH and run a fridge/freezer, separate freezer (24/7), electric head, lights, pumps, etc.

My panels are approx. 3 feet by 6 feet each in size. To optimize output, you could use several smaller panels, all with separate controller, but your cost to purchase and install would go way up (compared) and the gain might not be that great (if the available total watts were equal), therefore, cost to benefit may not be there.
Running the generator in the AM to make hotwater, bulk charge the batteries, (and whatever else you may need AC power for) would definitely almost guarantee having a good solar installation getting your batteries back to 100% each day. (I have found that generator running is not needed on most summer days here in western Canada). Your batteries will last longer if brought back to 100% charge (almost) everyday as a side benefit to solar. Without solar (or wind, etc) most boaters who do not "plug in" regularly do not get the batteries back to 100% near often enough for optimal battery life, and are in effect "murdering their batteries".
Hope this helps with your decision,
Tom
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Old 01-13-2019, 01:25 PM   #8
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Seevee, last summer was my first with solar panels so I can give you my experience. Two 350 watt panels, mppt controller, on the hook a lot in Alaska for three months. For my application, the panels don't eliminate the need for my other charging sources (genset, engine alternators, shore power), but they reduce it. I run the genset now about half the time I used to, to keep the batteries up. I see the panels as an always-on float charger when the sun is out, charging at 30-35 amps plus covering hotel loads. They are a great addition to my boat.
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Old 01-13-2019, 02:58 PM   #9
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Ken- two summers ago when we spent weeks on anchor or moorings, I had no trouble getting my batteries back to charge just using solar...my ginny was down. My load has remained the same for years now, an 8.3cuft apartment fridge with self defrost, two 32’’ tvs, lighting, Wifey uses microwave as needed. The fridge and microwave are powered via 3KW true sine wave converter that runs 24/7, loaded or unloaded. We are power pigs.

I mention above because having enough solar along with storage you should be able to live without a genny. Ours takes care of breakfast by powering our coffee pot and powering the hot water tank. When we were without the genny we only left the coffee pot on to make the stuff and then stored it in a thermo. Went with no hot water.
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Old 01-13-2019, 03:18 PM   #10
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It is tough to give advice to another user of solar because we all have different usages for electrical power. With a single 250 watt panel mono panel and 4 x 150Ah AGM house batteries running my Waeco fridge, lights, pumps, fans, chargers etc, it provides me all the power I need. I have only plugged into mains power a couple times for hot water when docked ( although I could have run the engine for half an hour). I don't have a generator and haven't used my mains charger since I installed the panel. Voltage has not dropped below 12.6V and is topped up by noon every day regardless of cloud cover.

Most TF members would have a greater power usage than me, so would likely need more panel area and batteries. The limiting factor will always be air conditioning. Most Florida boats wouldn't have enough real estate to mount the panels required to A/C. Even though we have similar temperatures, it is a dry heat (like San Diego) and benefit from cooling sea breezes when on or near the water, so a few fans make things comfortable on all but a few days a year.
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Old 01-13-2019, 03:36 PM   #11
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Foggy, Thanks for the info on your solar utilization, which is a good goal for me to shoot for on my boat. Ken
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Old 01-13-2019, 04:54 PM   #12
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Ken- solar is a gift that keeps on giving. Enjoy your boat
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Old 01-13-2019, 04:55 PM   #13
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Seevee:

I wrote a couple of articles on this subject that are in the Library section. To summarize your situation with a little interpretation:

12.2 volts overnight is about 60% state of charge or about .4*440= 176 AH to recharge fully. Plus another 5 amps during the day or about 60 AHs gives maybe 240 amp hours needed during daylight hours. That is a bunch of power and I don't really believe it, but let's stick with it for a while.

In average conditions a solar panel produces 0.3 * wattage rating during a sunny day, more in the summer or low latitudes, less in the winter or high latitudes so lets figure .35 for St Pete year round, also considering reduced output due to high heat. St Pete has about a 65% solar factor (pct sunniness) so the real output will be about .23* wattage.

So that means to put out 240 amp hours on average, it will take 240/.23= 1080 watts of panels.

I doubt if you need that much. If you use 5 amps during the day, how do you run the batteries down by 176 amps overnight. So lets redo the calcs based on 5 amps for 24 hours or 120 amp hours. That means 540 watts of panels.

You could put them on the boat deck behind the fly bridge but there probably isn't enough room for 500 watts, the rails will shade them part of the time and you can't store you dinghy up there.

Mounting the panels on the bimini is a good solution, but you need the semi flexible panels and I would just sew the corners to the bimini canvas. You should be able to get 500+ watts of panels up there and there should be no shading problems. This panel is rated at 150 watts and is only 7 lbs: https://www.amazon.com/SUAOKI-Monocr...le+solar+panel

So four of these panels should do the job, and you will need a 50 amp controller to work with these. I would suggest an MPPT controller made by one of the big US suppliers: Blue Seas, Morningstar, Outback, Midnight, Magnum, Schneider.

Since most of these flexible panels are a nominal 12V and MPPT controllers are designed to take 24V nominal, I would wire them in series/parallel. That would keep the maximum current down to about 18 amps or so total so use 10 gauge for the wiring from the terminal point on the parallel/series wiring to the controller inside your boat to keep the voltage drop mimimal.

Use big wire, at least #6 from the controller to the batteries and put a 50A fuse in the plus wire near the batteries to protect the wire from a short.

David
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Old 01-13-2019, 07:02 PM   #14
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Shade causes output drop to near nothing??? That is a well spread myth. A panel will provide output when illuminated and there is illuminance present even in shade.
The actual output in shade is dependent on the type of panel, how it is wired, and what is shaded. Solar cells work like an idea current source, and an array is a series connected daisy chain. If one cell does not conduct, the whole array is shut off to the same extent as that cell. Some panels have bypass diodes which will bypass a shaded cell (but your output voltage will drop and on parallel connected arrays will contribute little). Poly crystalline or amorphous cells are less susceptible.

The array on my house is 4.5 KW. If I put a shadow across one panel from a pipe, say 1.5" wide, the output drops by 80%. On the boat with semi-flexible cells, the shadow of one rigging line reduces the output to less than half. Yes, there is luminance present, but not much. Your eyes are a logarithmic sensor, solar cells are not. Even at very low luminance you will get voltage, just not much current. The array on my RV will keep the batteries topped up, even with a cover on it.
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Old 01-13-2019, 08:24 PM   #15
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DDW- I gave my experience with panels, my second set. My first panels were 4 each 140 watt polycrystalline with a PWM controller. Those could NOT be placed in series because of limitations on the controller.

My current panels do NOT exhibit the characteristics you describe above. Gulls splatter my panels frequently with essentially no reduced performance. Sure, there is output current with degradation during shaded conditions, not complete shutdown. My advice is for panel users to wire them anyway they believe performs best for them.

I do want to be clear about tests seen online showing a panel section blocked with either a rag or piece of cardboard. Those tests do not represent real life conditions. Those tests block admittance to all luminance. Simple shading from an obstruction does not prevent luminance from a solar panel. It there is visible light, there is luminance.
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Old 01-13-2019, 08:54 PM   #16
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Tom
Tom:

I am considering adding Solar this year. Since you are so close by, who did you buy from? How much of the installation work did you actually contract out?

I am thinking I will hang the panels from the side rails on my upper deck, (presently blue sunbrella in my avatar picture) so I will need panels that will fit in that space, which is less than 3' tall, but is long enough for a 6' panel. Roughly how many watts will I get in that location?

Thanks for your insight.
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Old 01-13-2019, 09:13 PM   #17
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Keith, if you can't get the panels you need in BC, Platt Electric in Bellingham is a good source.
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Old 01-13-2019, 09:31 PM   #18
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I installed 4 panels for 480W. I was unable to avoid some shading, so I wired them in parallel with diodes to minimize the shading impact. I've seen output as high as 385+ watts.

The MPPT controller I chose was a Midnite Sun "Kid". I had problems with RF noise in the VHF despite the addition of various ferrite chokes, and the original had to be replaced in warranty due to controller and display lockup. Service was great, they shipped the warranty unit out at N/C with a promise I'd return the failed one. That unit later developed a bad connection at the 30A fuse and melted the fuse ass'y, but no internal damage. So in all, I wouldn't recommend it. They make a "marine" unit, with the main difference being a battery temperature sensor. Feature-wise it's good, but I believe there are better choices.
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Old 01-13-2019, 10:15 PM   #19
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Thanks for all the replies.... need to digest a bit.

A few comments:
My batteries give me 220ah of power (12.2 which is 50% of full charge, info supplied by Lifeline batteries)
My typical usage is somewhere around 160 ah from the time I shut down til I fire up the engine to go somewhere the next day.
The major users are:

Item: Amps Hrs used Total usage
Portable freezer 3.1/ 12/ 37.2
Main fridge/freezer 2.3/ 24/ 55.2
Cabin lights 10/ 1/ 10
Anchor light 0.2/ 14/ 2.8
Bilge Pump ? 0.2/ 1/ 0.2

120v
Microwave 1000/ .5/ 6
Coffee Maker 950/ 2/ 24
Computer 0.67/ 2/ 1.34
Misc 20
Total 156.74a

Now pretty hard to get accurate numbers so the above is a guess, but after a day and a few extra microwaves or a second pot of coffee the voltage is at 12.2.

Really don't need to cover all that, but would be nice, but absolutely need to cover enough to get the majority of that and be able to top off the batteries later when anchored.

Thx again.
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Old 01-14-2019, 06:26 AM   #20
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Visit the alt energy suppliers . While making 12v or 24v to charge batteries was common for decades the coat and hassle of heavy wiring is now obsolete in many off grid homes.

Small (tiny) stand alone inverters now allow AC to be used to feed the system, with nice thin cheap wiring.


Microinverters

A microinverter is a small PV inverter that is mounted beneath and connected to an individual solar panel on the roof. Microinverters are wired in parallel and connected directly or indirectly to the circuit breaker panel and ultimately to the grid (net metered). DC to AC conversion takes place on the roof. Because micro inverters are connected in parallel, rather than in series, they are a simple solution for applications where there are shading issues on multiple mounting places (Direction and Pitch). The use of microinverters allow solar panels to produce power independently as opposed to string (central) inverters which require panels to produce as a group. In some cases- not all, The use of microinverters will result in superior energy harvest. Micro inverter systems offer free web monitoring and a 25 year warranty.
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