wires burned up with 4 100 watt panels

[Sailing Ohm]

Originally Posted by Cadence

Someone correct me if I'm wrong. My understanding is the panels produce a higher voltage and the controller knocks it down to charging levels. The 10ga. wire would seem more than adequate from the panels of 100W each.

You are wrong. If wired in series then yes but not when wired in parallel

[Sailing Ohm]

Originally Posted by John De Bree

Correct me if I'm wrong but the solar panels put out over 110v and I'm thinking that you are using a 12v fuse this maybe your problem

Fuses work by controlling amps not voltage.
His panels also do not put out 110V if they are 100 watt panels wired in parallel.

[Dsanduril]

Originally Posted by Sailing Ohm

This is bad advice and could burn your boat down and get you killed. You should always fuse or better yet put a fast acting breaker designed for solar between your solar panels and their charge controller for no other reason than to protect your charge controller.
This is standard advice from both the solar panel company and the charge controller company.

In theory a panel shouldn’t produce more than its rating but my rated 660 watts of solar routinely puts out 740 watts on those perfect days. Lab ratings are at a certain set temperature and lower ambient temperatures can cause higher output

Where, oh where, does the overcurrent come from to trip the breaker or blow the fuse between the controller and the panels?

[facciatosta]

Originally Posted by Sailing Ohm

This is bad advice and could burn your boat down and get you killed. You should always fuse or better yet put a fast acting breaker designed for solar between your solar panels and their charge controller for no other reason than to protect your charge controller.
This is standard advice from both the solar panel company and the charge controller company.

In theory a panel shouldn’t produce more than its rating but my rated 660 watts of solar routinely puts out 740 watts on those perfect days. Lab ratings are at a certain set temperature and lower ambient temperatures can cause higher output

Dsanduril is 100% correct.

[Sailing Ohm]

Forget the fuses and get a fast acting breaker designed for solar and rated for your system.
Your panels are rated at ~30 amp output at 12vdc. I’d get a 40 or 50 amp breaker (you always want more room on the breaker/fuse than the absolute minimal required)
Upsize your wire by one or two gauges. (Why play it so close?)

If you have mppt controller (if you don’t have one you should they are worth it) running panels in series will allow smaller gauge wire (if cost or hole size is an issue) and you’ll actually get more power long term.

If none of this makes sense hire someone.

[Sailing Ohm]

Originally Posted by Dsanduril

Where, oh where, does the overcurrent come from to trip the breaker or blow the fuse between the controller and the panels?

The sun... or short, whether in the panel or elsewhere.
Again a panels stated rating is at a controlled standard laboratory test parameter. If you have a lower panel surface temperature and the same amount of irradiance as at the lab you can and will a see higher panel output than what is its rating.
Standard Test Conditions are designed to allow a fair comparison of different panels to each other and represent an ideal scenario but not THE best possible. It is not uncommon to see 10% higher output than a panels rating if conditions are right.

[StuM]

Originally Posted by John De Bree

Correct me if I'm wrong but the solar panels put out over 110v and I'm thinking that you are using a 12v fuse this maybe your problem

You're wrong. On both counts.



Clearly you have little or no understaninfg of the subject. I would humbly request that you refrain from making further suggestions in similar threads until you learn a lot more about electrical systems.

[StuM]

Originally Posted by Apollo366

First Q; Why are you running only 100W panels? On a 42 ft sailboat you should be able to mount the very latest 300-400W 28V panels.

Maybe they are a few years old but still doing their job? A lot of us don't throw away things in working order just to have the latest and greatest

[Sailing Ohm]

Originally Posted by StuM

You're wrong. On both counts.



Clearly you have little or no understaninfg of the subject. I would humbly request that you refrain from making further suggestions in similar threads until you learn a lot more about electrical systems.

There is a lot of that going on here. It really has me worried for people’s safety...
I guess this is why ABYC electricians can make the big bucks

[sailingharry]

Originally Posted by StuM

Maybe they are a few years old but still doing their job? A lot of us don't throw away things in working order just to have the latest and greatest

This^^^^^
I have a 43' boat. I have two 90W Solbian flexible panels on the dodger, and two more on the arch, for 360W. They go to individual Genasun MPPT controllers, but still rarely give 10A total on a good day (ie, about 30W each, or 1/3 of rated power). Between budget, other priorities, and a veto by the Aesthetic Review Boardfor 300W panels (she has veto power), upgrading to even 200W panels is at least a year out.


Sure, it's great to have a cutting edge boat. But few of us can have cutting edge everything (and if we did, it would be due for an upgrade next week).

[Dsanduril]

Originally Posted by Sailing Ohm

The sun... or short, whether in the panel or elsewhere.
Again a panels stated rating is at a controlled standard laboratory test parameter. If you have a lower panel surface temperature and the same amount of irradiance as at the lab you can and will a see higher panel output than what is its rating.
Standard Test Conditions are designed to allow a fair comparison of different panels to each other and represent an ideal scenario but not THE best possible. It is not uncommon to see 10% higher output than a panels rating if conditions are right.

Yes, and every system design should take these factors into account. When we design a system for the Colorado Rockies it uses a panel temperature of -10 to -20C and insolation as high as 1200W/m2. Either way, the Isc for the design conditions is current limited.

You say your panels regularly produce 740W out of a 660W panel. Did your fast acting breaker or fuse trip? If not, why? Why would you recommend a 40 or 50A breaker for a 30A system? Where is the 33-66% source of overcurrent? Temperature coefficients for panel are on the order of 0.04%/C so from STC to -25C you might get a 2% increase in current. Solar irradiation at the upper edge of the atmosphere maxs out at about 1320 W/m2, and at the surface (sea level) even with cloud banding and other effects 1200 is about the maximum observed. Most overcurrent devices have a 20% overhead for continuous current just to avoid nuisance trips.

So, once again, what is your device doing? If it serving as a disconnect (sometimes useful), well there are easier choices. Otherwise it is just contributing two connections that could corrode, fail, or otherwise cause problems.

[Uncle Bob]

Originally Posted by Sailing Ohm

This is bad advice and could burn your boat down and get you killed. You should always fuse or better yet put a fast acting breaker designed for solar between your solar panels and their charge controller for no other reason than to protect your charge controller.
This is standard advice from both the solar panel company and the charge controller company.

In theory a panel shouldn’t produce more than its rating but my rated 660 watts of solar routinely puts out 740 watts on those perfect days. Lab ratings are at a certain set temperature and lower ambient temperatures can cause higher output

Funny that the panel supplier that I purchased my panels from and the manufacturer of the controller both say that the only fuse required is between the controller and the battery, specifically within 7 inches of the battery.

[boatpoker]

Originally Posted by Uncle Bob

Funny that the panel supplier that I purchased my panels from and the manufacturer of the controller both say that the only fuse required is between the controller and the battery, specifically within 7 inches of the battery.

Very curious, the manual that came with my controllers says circuit protection is required between the panels and controller ... and between batteries and controller

[sailingharry]

Boatpoker's observation doesn't make any sense, and doesn't seem to be dictated by ABYC (the current limiting exception). However, as strange as it seems, his observation seems to be accurate.


Victron schematic, here:
https://www.victronenergy.com/upload...PPT-100-30.pdf
shows a breaker between the panel and the MPPT, and at the connection of the MPPT to the bus.


Why? What fault is it protecting? It's easy to follow the manual, it's more helpful to understand.


I will say that after 10 minutes of trying, I could find no actual installation instructions, no specs on the size of that panel breaker, no guidance on where to install it, nothing. Hmm.....

[boatpoker]

Originally Posted by sailingharry

Boatpoker's observation doesn't make any sense, and doesn't seem to be dictated by ABYC (the current limiting exception). However, as strange as it seems, his observation seems to be accurate.


Victron schematic, here:
https://www.victronenergy.com/upload...PPT-100-30.pdf
shows a breaker between the panel and the MPPT, and at the connection of the MPPT to the bus.


Why? What fault is it protecting? It's easy to follow the manual, it's more helpful to understand.


I will say that after 10 minutes of trying, I could find no actual installation instructions, no specs on the size of that panel breaker, no guidance on where to install it, nothing. Hmm.....

A battery is a power source and requires circuit protection
Shorepower is a power source and requires circuit protection
An inverter is a power source and requires circuit protection
A generator is a power source and requires circuit protection
A solar panel is a power source and ...