Challenges with Solar on boats

[newhaul]

Originally Posted by ardbeg

The only thing I was warned, make sure the shore power is turned off before engaging solar and vice versa. I probably do not plug in more than 5 days per season.

Ok thats a new one on me was it just word of mouth from "the guy" or was/ is there documentation for doing this and what issues could happen? I have not heard this before and have many solar installs with shorepower plugged in at times and no issues.
What controller are you using?

[LoudMusic]

Originally Posted by Kenomac

Install separate controllers for each panel to eliminate as many shading issues as possible.

What about using more smaller panels instead of fewer larger panels?

[Kenomac]

Originally Posted by LoudMusic

What about using more smaller panels instead of fewer larger panels?

That's what I did. If I only used one controller, shade on any one of the panels would shut down the entire system. Which is why I used five individual controllers on high efficiency panels.

[john61ct]

yes, in fact the Maxim ICs let a vendor embed multiple MPPTs per panel rather than using blocking diodes.

wrt flex panels, make sure the mounting arrangement alliws for easy replacement and make sure to buy them cheap,$1.20-1.60 per watt

[Dave22q]

Be aware that the American Administration is investigating solar panel dumping from China. Those cheap panels may be going up in a few months.

[a64pilot]

I don't believe that if your wired in parallel that shade on one panel significantly affects the others, or at least on my installation it doesn't seem to. I have four wired to a combiner box and an Outback 80, I have shading issues but will see 300+ AH on a good day.
However I can see having multiple controllers gives redundancy, if I lose my Outback 80, I lose the whole system

[Mike OReilly]

My setup includes two 50 watt semi flex panels made in US. Had them for four seasons now, and still going strong. Those two are run in parallel with two more; 400 watts in total. All run to one mppt (victron).

Shading is not much of a problem with parallel panels, and the new mppt seems to do something to manage partial shading as well.

[Rorzech]

Wouldn't a MPPT controller take care of voltage drops in various panels? A system that's worthy is going to be 48 volts or higher to keep wire size down, so the panels will be most likely set up in parallel and series. If you have 12 volt panels, it's going to take 4 in series to get up to 48 volts. If you have some shadows you could be down to 30 volts but your MPPT controller should extract all the available power still. Wouldn't you think ?

[TheThunderbird]

Alas, i am totally NEGATIVE about my solar

I paid 1300eur for 2x150w flessibile panels by GIOCO SOLUTION (ITALY). MONO, 21% efficiency, with stupid PWRs.

Both panels had (loose) block insulation issues upfront , and were changed (at a cost, and no excuse).

though in Sicily, flat on bimini, i never saw more than 6.8A on 13V.

Well, not always, it is so ONLY between 11am and 2pm,otherwise efficiency falls much Lower.

1350eur to care for topping of a 1200eur house bank.

No more!

Though my products proved MISERABLE, i Believe many users dont want to see the reality of their magic panels. (All rated for 90° cold light... come on gentlemen...)

[socaldmax]

Originally Posted by LoudMusic

What about using more smaller panels instead of fewer larger panels?

If you did that, you'd be wasting your time, money, and valuable space on your boat. Why waste time bolting down 3 100w panels when you can simply bolt down 1 300w panel?

As I tell customers, I don't even pick up the drill for panels smaller than 200w.

Based on the prices at my distributor, 100w panels cost $65 (65cents/watt), his 280w panels are the big bargain at $86 ea (30.7 cents/watt), the 230w panels are $72 (31.3 cents/watt) and the 320w panels come in 3rd at $119 ea (37.2 cents/watt.) Why pay more for less? Another nice side benefit is I can use a cheap 20A controller connected to each 320w or 280w panel and get 20A or close to it at peak summer hrs and not worry about series connected panel shading or even shading losses in parallel from the loss of MPPT efficiency. Large panel efficiency and one controller per panel gives max MPPT harvest.

Finally, the 100w panels are quite often less efficient than the 300w panels, so not only do they take up a lot more space, they produce less power per sq ft, which is a bad thing on a boat. You want the most efficient use of your limited space.

[downunder]

Originally Posted by socaldmax

If you did that, you'd be wasting your time, money, and valuable space on your boat. Why waste time bolting down 3 100w panels when you can simply bolt down 1 300w panel?

As I tell customers, I don't even pick up the drill for panels smaller than 200w.

Based on the prices at my distributor, 100w panels cost $65 (65cents/watt), his 280w panels are the big bargain at $86 ea (30.7 cents/watt), the 230w panels are $72 (31.3 cents/watt) and the 320w panels come in 3rd at $119 ea (37.2 cents/watt.) Why pay more for less? Another nice side benefit is I can use a cheap 20A controller connected to each 320w or 280w panel and get 20A or close to it at peak summer hrs and not worry about series connected panel shading or even shading losses in parallel from the loss of MPPT efficiency. Large panel efficiency and one controller per panel gives max MPPT harvest.

Finally, the 100w panels are quite often less efficient than the 300w panels, so not only do they take up a lot more space, they produce less power per sq ft, which is a bad thing on a boat. You want the most efficient use of your limited space.

+1

[socaldmax]

Originally Posted by TheThunderbird

Alas, i am totally NEGATIVE about my solar

I paid 1300eur for 2x150w flessibile panels by GIOCO SOLUTION (ITALY). MONO, 21% efficiency, with stupid PWRs.

Both panels had (loose) block insulation issues upfront , and were changed (at a cost, and no excuse).

though in Sicily, flat on bimini, i never saw more than 6.8A on 13V.

Well, not always, it is so ONLY between 11am and 2pm,otherwise efficiency falls much Lower.

1350eur to care for topping of a 1200eur house bank.

No more!

Though my products proved MISERABLE, i Believe many users dont want to see the reality of their magic panels. (All rated for 90° cold light... come on gentlemen...)

I'm sorry you had such a terrible experience! Believe me, your poor solar performance revolved around bad solar panels. I've got probably 40 very satisfied solar customers and they're getting exactly the output that they were told to expect from their systems.

I even had one customer call me late at night on a very bright full moon night and tell me he was getting a very slight charge from the moonlight! I jokingly told him he was crazy and he snapped a pic with his phone. He was only producing .1A, but we were both laughing because it was something! That was on a 420w system feeding a single MPPT controller.

Don't be scared off, I'd try again, just be more diligent in your solar panel selection, and don't overpay for it, it shouldn't cost that much!

[Julian Alcorso]

Hi all, not sure if my experience is relevant but I have just under 4kW of solar and 2,000 amp hours of storage (12 X 2 kW batteries) on my boat.
We had absolutely no issues at all with the installation and it all works brilliantly. Admittedly the package cost over AUD$30,000 but well worth the money.
All controllers and the 8kW inverter are from VICTRON ENERGY. The batteries are German Sonnenshein (or something like that?)
We spend almost all our time 'off the grid' even when in ports or marinas. The boat runs 24V and 240V and the solar system works brilliantly. Of course we have a gen. set but this almost never used.
I am certain that the Victron gear could be adapted right down to one or two panels. Good Luck!

[Kenomac]

Originally Posted by Mike OReilly

My setup includes two 50 watt semi flex panels made in US. Had them for four seasons now, and still going strong. Those two are run in parallel with two more; 400 watts in total. All run to one mppt (victron).

Shading is not much of a problem with parallel panels, and the new mppt seems to do something to manage partial shading as well.

Mike,

What do you do on days like I'm experiencing today? Cloudy and zero wind. Is it a day for you to run the engine? Solar production is down 80%

[Mike OReilly]

Originally Posted by Kenomac

Mike,

What do you do on days like I'm experiencing today? Cloudy and zero wind. Is it a day for you to run the engine? Solar production is down 80%

Funny you should ask. We are into our third crappy day of rain and little wind here. Batteries are really taking a beating. So yes, if we don’t get a good solar/wind boost today we’ll have to either run the engine (big diesel or small generator), or turn off the fridge.