Boat based solar failures

[BobR]

This is an article in Professional Boatbuilder magazine by Rod Collins; owner of 'Compass Marine' and the website MarineHowTo.com.

This would also be relevant to the Up In Smoke thread.


https://www.proboat.com/2022/07/solar-charge-controller-failures/

 

[A.Justice]

That was a very informative article, and seemed unbiased.

I know there's people on here who run 48v and higher systems in mobile or marine environments, but personally, in an RV or boat I would never run over 24v. I'd keep the panels under 36v or so as well. I want as close to 0 potential shock hazard as possible on something that can be crashed and smashed.

 

[BobR]

Rod Collins is the real deal and has a lot of marine knowledge.

 

[BobR]

I don't see any advantage to using anything higher than 24 volt in a mobile application.

That being said; at one time I had a commercial fishing boat that had a 32 volt system for electronics; ( Back in the Dark Ages ).

 

[foggysail]

I have my boat's 4 solar panels connected as two in parallel connected in series to another two in parallel. My intention for the series connection that produces close to 70VDC is to minimize the wire size between the panels mounted onto hardtops and the controller below. The wire span is about 25 feet and for losses, the electrical path is double that for close to 50 feet.

I am using two pairs of #10 wire between the panels and the Victron controller to maximize getting useable power rather than heating wire with losses. I see no reasons to avoid higher voltages on boats. Do things correctly and there will be no problems

 

[foggysail]

That was a very informative article, and seemed unbiased.

I know there's people on here who run 48v and higher systems in mobile or marine environments, but personally, in an RV or boat I would never run over 24v. I'd keep the panels under 36v or so as well. I want as close to 0 potential shock hazard as possible on something that can be crashed and smashed.

24V maximum????

Nonsense! Most larger RV's & boats enjoy AC, TV's and refrigeration that operate at 120VAC whether provided by generators, inverters or power cords. My boat has a 240VAC split phase dock power connection

 

[BobR]

24V maximum????

Nonsense! Most larger RV's & boats enjoy AC, TV's and refrigeration that operate at 120VAC whether provided by generators, inverters or power cords. My boat has a 240VAC split phase dock power connection

On boats when we (I) say 24 volts we are talking about the DC side of our systems. The main reason to stay at 24 volts DC is the availability of 24V DC marine electronics.

 

[foggysail]

Thanks for the clarification. DC from a continuous power source greater than 48V is certainly hazardous and proper care must be exercised. Even the telephone system used 48VDC right up to the phones themselves BUT was power limited.

 

[A.Justice]

....Even the telephone system used 48VDC right up to the phones themselves BUT was power limited.

When I was a kid, I used the telephone jack as a DC power supply for small projects. It would easily light LED's and run small "play" circuits. IIRC, it was something like 35-40v at the wall jack.

 

[Shimmy]

On boats when we (I) say 24 volts we are talking about the DC side of our systems. The main reason to stay at 24 volts DC is the availability of 24V DC marine electronics.

Personally, I don't understand running a 400A circuit at 24V to a bow thruster; 200A and 48V seem much more logical.

 

[Rocketman]

I expect over the next few years we will see more “electric” drive boats. Many DC drive motors are 48v and I have seen some at 96v & 108v DC. So I think high voltage DC is just getting started on Marine applications.

I did really like the caution about cheap components vs tier-1 components. I think sometimes people on our site just go - it’s a SCC or a BMS - why spend more…. This cheap one will work. Until it doesn’t…

 

[Goboatingnow]

Good article. What it brings home is the susceptibility of mosfets to high voltage ( >50 ) what’s really needed is spike arresters in bms system and protective crowbar circuits to trip fuses so that unexpected high voltage excursions are mitigated and equipment doesn’t fail

We really are missing a few key components in boat systems

 

[Shimmy]

What’s really needed is spike arresters in bms system and protective crowbar circuits to trip fuses so that unexpected high voltage excursions are mitigated and equipment doesn’t fail

In practice that is really hard to acheive (in an energy-efficient system). You just need a microsecond of excess voltage to fry the solid-state components, so you end up needing to add R-C circuits to each risky voltage source to slow the voltage rise and let a MOV absorb the energy. The negative feedback loop is a pain though (apparently).

 

[Goboatingnow]

In practice that is really hard to acheive (in an energy-efficient system). You just need a microsecond of excess voltage to fry the solid-state components, so you end up needing to add R-C circuits to each risky voltage source to slow the voltage rise and let a MOV absorb the energy. The negative feedback loop is a pain though (apparently).

Not really true. It’s a multi stage process. First you use TVS diodes to quench the initial spike. These can handle 5000 watts for about 20 uS and clamp the spike to about 30v , this then gives time for the crowbar circuit to react and blow the fuse. Movs are too slow for fast spike applications.



It is done and can be done.