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Old 18-01-2021, 04:29   #31
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Re: Just upgrade to a new panel - data is in

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Originally Posted by stormalong View Post
Looking at your picture it appears that the boom extends over the center of the Bimini. Solar panels are very susceptible to shading. Even the slightest amount kills the power output.

Can you move the panel outboard to reduce the shading? A second panel could provide power when the first is shaded but they must be in parallel, not in series.
Yeah... the panel is actually totally in the sun in this picture. The dark spot in the lower right corner is a reflection of the blue canvas, captured by the camera.



I can kick the boom over a bit more as needed.
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Old 18-01-2021, 04:52   #32
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Re: Just upgrade to a new panel - data is in

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I have to agree with Billkny. Use your genset in the morning and let the solar panels top off the batteries during the rest of the day
My 2-360W Sunpower panels routinely put out the rated current of 60 amps through 2 Victron 100/30 mppts. We have 840 ah of AGMs that are only discharged down to about 93% overnight acoording to our Victron 702 monitor. We run separate fridge and freezer and our Seawaterpro water maker(1 hr daily). The only time we use the genset is after several overcast days. Its nice to have the little NextGen 3.5 kw diesel to back up our PV system and to run the A/C on those really hot breezeless days.
The attached screenshots show the output of both panels at about the same time.
Wow. The performance of your panels and your house electrical hardware is really great. I am impressed that you only need 59 Ah overnight into your house load. I use 3x that amount. (15 A x 12 hour). It is the fridge, plus the masthead light, and fans (mainly fridge). You have really efficient hardware on your boat. It is also really impressive that you can make enough water with solar. My water maker pulls 8 amps of 110 VAC, so it is a kilowatt. Running thru an inverter from 12v it would be 1.3 kw. Makes a lot of water fast ... 30 gal/h. But it takes some juice to run it. It would consume my entire daily energy from my panel to run it for one hour.

I am guessing you are in Florida? My wife and I used A/C at night a few times there last year, just for a couple of hours after sundown to cool the aft cabin and keep out the bugs. I don't seem to need it here in the Caribbean on anchor, if I am far enough from land. The trade winds are pretty solid from now til May. If you get too close to land the bugs will get you here and you have to close up or try to screen all the hatches and ports (not usually worth it - screens fine enough stop the bugs seem to stop the air, too). These bugs carry Dengue, Chikungunya, Zika, and Malaria, so it is not just about comfort.
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Old 18-01-2021, 06:20   #33
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Re: Just upgrade to a new panel - data is in

Both of our refrigeration units use Danfoss 50 series compressors with the isotherm energy efficient module which varies the compressor speed and low temperature setting according to the battery bank voltage. So...in bright sun and/or when there is ICE power, the compressor runs wide open and carefully limits the fridge to 33 deg F.
The numbers I've used are when we are on the hook in the northern Bahamas. The SeawaterPro watermaker uses 9A at 120V which equates to about 90A at 12V. By running the watermaker after the batteries are fully charged we only are drawing 30-40A out of the battery bank as the PV panels are putting out 50-60A in full, bright, overhead sun. Our panels are mounted on a custom davit structure that hangs over the stern which usually eliminates any shading.
We run the watermaker about 30-45 minutes a day at ~20 GPH as the Admiral likes to take a nice shower and wash her hair every evening. We also rinse off after each time we go for a swim. Sometimes up to 10 times a day.
On the hook, we are energy independent as long as we don't run into too many cloudy days.
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Old 18-01-2021, 07:46   #34
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Re: Just upgrade to a new panel - data is in

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I used accounts for the extra energy needed to charge the batteries. So, I believe I would need another real, sustained 1 kw. How many panels is that? So, far, looking at mid-day power levels, I see about 65% of the "labeled" power, 250-260 watts vs 400 watts). So, about 1.5 kw (label). 4 more of my
It sounds like you are very happy keeping a generator, but for others reading the thread it is important to understand that running a boat via solar involves not just the solar installation itself, but also installing equipment and energy systems that are compatible.

This should not mean doing without creature comforts, but it does involve choosing energy efficient equipment and designing suitable systems.

When considering moving from a boat designed around a generator based charging system to a boat where solar provides most of the electrical power, calculating the required size of the solar array based on the existing electrical consumption will often lead to the conclusion that an unpractically large array will be needed. The above calculation is an example of this.

So when considering if solar is practical as the primary power source, look at the system as a whole rather than a simple generator/solar panel substitution. The cost of equipment and systems modifications required should be considered along with the cost of the actual solar hardware itself.
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Old 18-01-2021, 07:49   #35
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Re: Just upgrade to a new panel - data is in

Instead of a panel on a halyard, what about making the extra panel effectively an extension of the bimini over the side deck? Install the hinge like you were planning, but instead of a halyard, mount a pair of supports going out to the rail. Then you can leave the panel folded out more often (including when sailing), but can still detach the supports and fold it when desired.
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Old 20-01-2021, 06:17   #36
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Re: Just upgrade to a new panel - data is in

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It sounds like you are very happy keeping a generator, but for others reading the thread it is important to understand that running a boat via solar involves not just the solar installation itself, but also installing equipment and energy systems that are compatible.

This should not mean doing without creature comforts, but it does involve choosing energy efficient equipment and designing suitable systems.

When considering moving from a boat designed around a generator based charging system to a boat where solar provides most of the electrical power, calculating the required size of the solar array based on the existing electrical consumption will often lead to the conclusion that an unpractically large array will be needed. The above calculation is an example of this.

So when considering if solar is practical as the primary power source, look at the system as a whole rather than a simple generator/solar panel substitution. The cost of equipment and systems modifications required should be considered along with the cost of the actual solar hardware itself.
Very good summary. Having efficient appliances is really critical. It is also not that easy on old boats.

To prove your point, I have to confess something. I just now got around to replacing some lost refrigerant from my recent Atlantic passage, and that really helped my freezer. On passage I had to empty my spillover fridge box into an igloo electric cooler, as a backup fridge, in order to keep my freezer box from thawing. Now that it is recharged and working well, I am using the spillover fridge box again. Unpluging the igloo cooler reduces the house load from 12A to 7A. Not bad, huh? Pretty huge. The beer cooler pulls about 5 amps.

With that, and the good advice I got on this thread to run the genset in the morning, I have achieved the goals of needing just one two-hour genset session per day, which I use to also make water and chill beer :-).


I would be great to just use solar, but it would require a lot more capex than I am prepared to spend.
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Old 24-01-2021, 08:38   #37
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Re: Just upgrade to a new panel - data is in

A few questions to you experienced owners of solid solar panels :

How is corrosion from salt water affecting the panels ?
Are they in general "rust proof" ?
If not, are high-priced panels more long-lasting than cheaper panels ?
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Old 24-01-2021, 09:03   #38
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Re: Just upgrade to a new panel - data is in

Carsten,


After two years , with the boat from Florida to Maine and the Chesapeake, the only thing showing any corrosion is some of the 304 stainless bolts/nuts in the fastening blocks. Interestingly, they aren't rusting where they touch aluminum, but just on the exposed ends or in the threads where they meet. The panels themselves look like the day I put them in. We have 5 Newpowa 175 watt panels.
The fastening blocks are these: https://smile.amazon.com/gp/product/B008EPC0RO/ The corrosion (rusting, really) is minor, but noticable.

Hartley
S/V Atsa
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Old 24-01-2021, 19:56   #39
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Re: Just upgrade to a new panel - data is in

Thanks, Hartleyg !
I checked some reviews of Newpowa, they seems fine for the price.
For not getting any rust stains on your deck, consider changing the bolts/nuts to 316 grade.
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Old 25-01-2021, 21:18   #40
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Re: Just upgrade to a new panel - data is in

Flexible panels are garbage. They rarely break 12% efficiency while modern rigid mono panels can do 20+% no problem.

derfy What is the peak voltage of your panel? I wonder if your panel is dropping below the threshold of your charger. If you do add a second panel be sure to put it in series and double check they have bypass diodes so the shaded panel doesn't kill your system. Also watch you dont exceed peak voltage for your charger with the second panel.
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Old 24-02-2021, 04:50   #41
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Re: Just upgrade to a new panel - data is in

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Flexible panels are garbage. They rarely break 12% efficiency while modern rigid mono panels can do 20+% no problem.

derfy What is the peak voltage of your panel? I wonder if your panel is dropping below the threshold of your charger. If you do add a second panel be sure to put it in series and double check they have bypass diodes so the shaded panel doesn't kill your system. Also watch you dont exceed peak voltage for your charger with the second panel.

My Outback charger handles PV voltage down to 12 Vdc, with a max rating of 145 Vdc. The typical Pv range is 12-60 Vdc. It handles 60 Amp max on the 12 volt output side. It only down converts, and I do not know the drop out voltage, but I am guessing it would quit when the PV voltage drops below, say, 15 volts.

I do not have a datasheet on my panel, but logs show it reaching 45 Vdc max, at mid-day. Typically 6-7 amps max are seen at that voltage on the PV side. I have only one panel/array.

In early morning light, when it is barely producing power (ie 0.5 amps on the PV side), I see already 28 Vdc on PV side.

Why do you think it is dropping out?

I am still considering a second panel. Kicking the boom way over to one side would likely expose the north side panel (ie port panel) to reasonable sun. But, the angle would be obtuse and hence I would expect the second panel to boost daytime production by only 50%. I might almost be enough to eliminate running the genset, at least some mornings.

Truth be known, I would need to replace my house battery bank to take advantage of the extra solar. I am fully topped up at 4pm, and by 5:30am I am down to 12.2 V and need to crank the genset up. I use about 121 A-hr each night between 4 pm and 5:30 am. The genset then runs for 1.5 hr and puts back about 75 A-hr. The other 46 A-hr is contributed by the solar panel during the day, whilst it also handles the house load.

Four brand new 4D size batteries in not in this fiscal year.
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