Illustrated Guide to Solar Installations on Boats

[aybabtme]

I love your optimism that the MPPT will never turn off. We need optimism in these times, or always really. :thumbs_up:

[aybabtme]

To be fair, it probably won't cause any problem, except in the case where it will.

[Iains boatyard]

Sadly poor rebuttal I was hoping for some science.
Factors to consider the outputs and load are shared between two controllers
Factor in the temperature, my average day time temp is 33 degrees plus panels temp way above that something I will check today. So output reduces.
If I am really worried I can put a small load on the out put other than the bank constantly on.
The controller is a load across the solar panels so no open circuit should occur. I doubt I will ever reach open circuit volts.
How ever Murphy’s law states if it can happen it will !
If I was that worried I would be to scared to live!

[Iains boatyard]

Current panel temp close to full sun 48.9 degrees C.
So guessing about 80% efficient. So output derated.

[mitiempo]

Originally Posted by Iains boatyard

Ok my opinion was no need to factor in open circuit volts. I take full responsibility for my work I never install for any one else. All my solar at connections I do at night.
So testing day one, 3 panels in to one controller hit 95v so right up there. 2 panels series into one controller 66v.
That night I wired the the panels same configuration into a bus bar feeding both the controllers in parallel to the bank.
Peak volts at midday topped 70 v and 36 amps output at about 26.5 v.
However the day was slightly overcast. I think the volts will climb higher on a clear day.
My instinct says maybe 80v and hopefully 40 amps but it is all subjective considering sun and and state of charge.
Monitor again today but slightly over cast again. Thinking this will be the best combination for my situation without building a sun tracking frame. One more lockdown project done.
Unown brand of controller came with the panel kit ML 2440 MPPT solar charge controller.
User adjustable ?

So you do have 3 panels in series?

The voltage should not vary much as long as the sun shines in a given climate. Cooler temps will cause the voltage to increase though. The amperage will be the big variance.

MPPT controllers are only MPPT in bulk. When they go into absorption they use PWM to maintain voltage, switching on and off very quickly to do this.

[Mag3]

alright hive mind - who do you like for solar...i'm looking to do these on the davits of my boat and can fit 2-3 reasonably sized panels 300-400 watt... i assume i want monocrystalline.. but what brands are the best in terms of efficiency, durability, and life assuming price isn't an option?

[Iains boatyard]

I used Canadian Solar 265w panels because they were easily available from a reputable supplier who had all the necessary parts and he delivered. Plus they fitted my space perfectly, price was not an factor I do like the bigger Panasonic’s but they were not a good fit. I have 5 panels in series into two controllers. Two circuits from the panels.
The suppler is the local Yacht surveyor who sells and installs solar and battery system guarantees his work. Could have got cheaper no name China but the suppler had no clue !
The build quality looks good. All from China some good some cheap.

[RickG]

Originally Posted by Mag3

alright hive mind - who do you like for solar...i'm looking to do these on the davits of my boat and can fit 2-3 reasonably sized panels 300-400 watt... i assume i want monocrystalline.. but what brands are the best in terms of efficiency, durability, and life assuming price isn't an option?

We’re happy with our Panasonic N330 ridges panels. They are not Marine rated. At less than $1/watt if one died I would just replace it. We see about 1.6kWhr per panel per day in the USVI. These panels are frequently used in residential applications and you can frequently by project leftovers for $0.50 or less per watt.

Cheers, RickG

[mikedefieslife]

Originally Posted by Mag3

alright hive mind - who do you like for solar...i'm looking to do these on the davits of my boat and can fit 2-3 reasonably sized panels 300-400 watt... i assume i want monocrystalline.. but what brands are the best in terms of efficiency, durability, and life assuming price isn't an option?

Last time I checked the lg neon r were among the most efficient publicly available. 21.7%

Sunpower X is better at 22.8% but not easily available around the world. Or Candian solar bifacial panels add another 1 per cent to that, but again can't easily be bought.

[bcboomer]

I see some installations that have the back-stay between panels.

Do you need to allow for some lateral movement of the back-stay?

[Roshni]

Hi
Replacing 5x 85 w panels (faulty old)with two 320W panels.
Have a Victron MPPT controller 100 30.
Do I need larger controller.
Could I use same controller if used 2 * 250 w panels.
Want to use as much of present wiring as possible. Many suppliers wanting me to do multiple controllers but would then need significant cabling.
Thanks for help.

[FlyingScot]

Originally Posted by Roshni

Hi
Replacing 5x 85 w panels (faulty old)with two 320W panels.
Have a Victron MPPT controller 100 30.
Do I need larger controller.
Could I use same controller if used 2 * 250 w panels.
Want to use as much of present wiring as possible. Many suppliers wanting me to do multiple controllers but would then need significant cabling.
Thanks for help.

You need two of them. Each one is good for about 400wp at 12v. If 24v house batteries you are good.

[Roshni]

Hi, thanks for help. These are the 310w panels I'm looking at in Grenada. do they look ok? Thanks

Model CRB/SF-6M310
Tolerance 0~5W
Max System Voltage DC1000W
Max Power (W) 310W
Max Power Voltage (Vmp) 33.00V
Max Power Current (Imp) 9.4V
Open Circuit Voltage (Voc) 40.50V
Short Circuit Current (Isc) 9.92A
Weight 18Kgs
Module Application Class A
Size L/B/T 1640x992x35mm

[mikedefieslife]

Originally Posted by Roshni

Hi
Replacing 5x 85 w panels (faulty old)with two 320W panels.
Have a Victron MPPT controller 100 30.
Do I need larger controller.
Could I use same controller if used 2 * 250 w panels.
Want to use as much of present wiring as possible. Many suppliers wanting me to do multiple controllers but would then need significant cabling.
Thanks for help.

Yep you certainly do. Victron controllers don't like being run anywhere near their limit.

I have a 100/20 that regularly sees 18a. It melted the plastic on the fuse.

I have another 75/15 that sees close to 11-12a for most of the day. It's plastic housing is getting discoloured.

I'll be upgrading them as soon as I can.

[Quebramar]

Originally Posted by mikedefieslife

Victron controllers don't like being run anywhere near their limit.

I have a 100/20 that regularly sees 18a. It melted the plastic on the fuse.

I have another 75/15 that sees close to 11-12a for most of the day. It's plastic housing is getting discoloured.

.

Thank you Mike, these are good insights. I love Victron’s Bluetooth feature and it’s good to know they are smart yet not quite tough, need to be gentle to them [emoji6]