SAE 2-pin vs MC4?

[chriscampbell]

I found this post in my search for information about a simple solar setup.

Solar charging options

I've heard that a good rule of thumb is to estimate that you'll get ~5 hours per day of your panel's maximum power, spread over ~12 daylight hours. So a 50w panel might deliver ~250 watt-hours. In reality, it will be much less than 50w in the morning and evening, and only come close to peak...

forums.sailboatowners.com

This sounds close to what I'm trying to do. I like the idea of using the SAE 2-pin cable because that seems easier and simpler. But, is it okay to use those and leave them exposed in the cockpit while I'm away from the boat during the week?

 

[Brian D]

Really, you can do anything you want, but then there is the ABYC you might have to contend with. Even tie the two wires together and cover it with heatshrink tubing. However, the reason for the MC4 was to prevent you (an understood you, not you personally) connecting (+) to (-) which can happen very easily. But if you want to use a different type of connector then go for it. Just keep the contacts protected so no corrosion get into the contact and setup of some kind of resistance. Sometimes easy and simple is NOT the correct solution.

 

[jeepbluetj]

The SAE connector is also polarized, so no problem there. Most of them have covers to keep them clean when disconnected.

You really don't need to fuse the panels, but you do need to fuse the controller. Standard boat rules apply: fuse the wire, close to battery, etc..

 

[thinwater]

I have used SAE 2-pins for decades. Yes, they are polarized. You will need to keep them filled with grease, which is easy. The are available in both wire-to-wire and bulkhead versions. Pretty common on RV solar. I use one for my tiller pilot, after the factory plug died.

They have been the standard for charging motor cycles and other uses for ~ 50 years because they work. Not as waterproof, but more compact.

 

[chriscampbell]

I have used SAE 2-pins for decades. Yes, they are polarized. You will need to keep them filled with grease, which is easy. The are available in both wire-to-wire and bulkhead versions. Pretty common on RV solar. I use one for my tiller pilot, after the factory plug died.

They have been the standard for charging motor cycles and other uses for ~ 50 years because they work. Not as waterproof, but more compact.

Thanks!

 

[LeeandRick]

Really, you can do anything you want, but then there is the ABYC you might have to contend with. Even tie the two wires together and cover it with heatshrink tubing. However, the reason for the MC4 was to prevent you (an understood you, not you personally) connecting (+) to (-) which can happen very easily. But if you want to use a different type of connector then go for it. Just keep the contacts protected so no corrosion get into the contact and setup of some kind of resistance. Sometimes easy and simple is NOT the correct solution.

@Brian D I'll disagree with you on the reason for MC4. The main reason was the high voltage attained when PV panels were put into series on home and commercial PV panel installations. You are correct on polarity issue. This is why they have a 600 volt rating and safety interlocks. I've installed systems that are over 400 volts at the end. In a 12-24 volt system get a MC4 extension and cut it in half to connect to the MC4 on the panel and then to whatever connector you want to use. Read the panel warranty, if you cut the MC4 from the end of the panel, warranty is void.

 

[chriscampbell]

@Brian D I'll disagree with you on the reason for MC4. The main reason was the high voltage attained when PV panels were put into series on home and commercial PV panel installations. You are correct on polarity issue. This is why they have a 600 volt rating and safety interlocks. I've installed systems that are over 400 volts at the end. In a 12-24 volt system get a MC4 extension and cut it in half to connect to the MC4 on the panel and then to whatever connector you want to use. Read the panel warranty, if you cut the MC4 from the end of the panel, warranty is void.

Cutting an extension in half is brilliant! Can’t believe I didn’t think of that. The panel I’m looking at (the Renogy 30watt) does not come with MC4 connectors. It’s just bare leads. But I could buy a pair of extensions and cut them both in half and use butt connectors to join them.

 

[Brian D]

My concern is this, if the connectors are swapped out for non OEM connectors and there is a fire, and, if the investigation finds that the fire was caused by non OEM connectors on the solar panels, then, that owner will be liable for damage done to other vessels/marina facilities.The insurance company may not pay. That is all I am saying. However, like I said in the beginning, the OP can do anything they want. I think MC4s are a PITA and I too do not like them, but they came with my panel and that is the end of that. JMHO

 

[chriscampbell]

My concern is this, if the connectors are swapped out for non OEM connectors and there is a fire, and, if the investigation finds that the fire was caused by non OEM connectors on the solar panels, then, that owner will be liable for damage done to other vessels/marina facilities.The insurance company may not pay. That is all I am saying. However, like I said in the beginning, the OP can do anything they want. I think MC4s are a PITA and I too do not like them, but they came with my panel and that is the end of that. JMHO

A lot of the smaller panels I'm seeing do not come with connectors, which is why I'm researching my options. For example, this one:

30 Watt 12 Volt Monocrystalline Solar Panel (New Edition)

Renogy 30 Watt monocrystalline solar Panel is ideal for recharging small electronics while away from the power Grid.

www.renogy.com

 

[Brian D]

Understood, but you could still be held liable. Just saying.

 

[thinwater]

Understood, but you could still be held liable. Just saying.

I am all for careful work, but forum fear-mongering is really tiresome.