Panel recommendations

[Salisburytree]

The problem with breakers is that DC interruption is inherently harder and you need to really understand the implications of different approaches, and TRUST it's not a counterfeit etc.

Fuses work with much simpler electrical engineering theory, and there's less variation (I think speed, steady state current, interrupt rating). I wouldn't be worried about them being a consumable. If you blow a pricy 100a fuse, that fuse saved you from some extreme pain, a

I understand it is harder to stop an arc with DC as apposed to AC, the latest breakers Renogy sell also use magnets inside the breaker to extinguish the arc.

I would have hoped that Renogy wouldn't be selling counterfeits, has this been known with them in the past? I will do some googling to see what comes up.

Initially leaning toward breakers over fuses for the manual capability of breaking the circuit when required rather than adding an isolator to a crowded electric cabinet.

Thanks for your reply.

 

[zanydroid]

I understand it is harder to stop an arc with DC as apposed to AC, the latest breakers Renogy sell also use magnets inside the breaker to extinguish the arc.

There's some (current?) polarity issue that I don't really understand yet. I think a battery needs non-polarized DC. Also there is more available current with a battery than solar panel. If your BMS fails closed (quite possible for FET-style one I AFAIK) at the same time as an incident, and it leaves the discharge path fully connected, you'll go up to the full available current of the battery... IE when BMS works properly, it will limit the available fault current, but if the shit hits the fan it might not be functional.

Batteries do sometimes come with disconnect breakers.

 

[Salisburytree]

There's some (current?) polarity issue that I don't really understand yet. I think a battery needs non-polarized DC. Also there is more available current with a battery than solar panel. If your BMS fails closed (quite possible for FET-style one I AFAIK) at the same time as an incident, and it leaves the discharge path fully connected, you'll go up to the full available current of the battery... IE when BMS works properly, it will limit the available fault current, but if the shit hits the fan it might not be functional.

Batteries do sometimes come with disconnect breakers.

If I'm following you right, a common fault with these breakers is the polarity heading the wrong direction causing the arc to almost intense.

As far as the description goes these breakers can flow both directions and are also suitable for manual switching as iv read this can also be an issue.

 

[zanydroid]

Cool, yes I was talking about bidirectional. For solar panels it's can be less important b/c it often only goes in one direction while batteries always go both (although there are solar panel fault cases where current can go both directions; another thing simpler with solar panels is the much lower available current).

Even though these are switch rated, it's usually a better general electrical practice to NOT switch things under load. Might help it last longer. Also keeps you more aware of how your system works.

 

[Salisburytree]

Cool, yes I was talking about bidirectional. For solar panels it's can be less important b/c it often only goes in one direction while batteries always go both (although there are solar panel fault cases where current can go both directions; another thing simpler with solar panels is the much lower available current).

Even though these are switch rated, it's usually a better general electrical practice to NOT switch things under load. Might help it last longer. Also keeps you more aware of how your system works.

Could I ask what you would recommend as a switch/isolation method in the case of me wanting to perform maintenance etc.

Presumably a straight forward isolator switch would suffer with the same arcing difficulties that breakers do?

 

[zanydroid]

Could I ask what you would recommend as a switch/isolation method in the case of me wanting to perform maintenance etc.

Presumably a straight forward isolator switch would suffer with the same arcing difficulties that breakers do?

You turn off your loads first. Then you turn the isolator / breakers. For a hybrid or AIO you turn it off so no loads can be powered. And those loads are on AC so disconnect switches are cheap. Perhaps a DC-rated switch (that doesn't have breaker or isolator functionality in it) can be found for less money, and you start by turning those off. And each switch might switch a small fraction of the total current/power so it takes a smaller hit.

I don't recall what equipment you are powering.

I guess another approach is to decrease as much as possible so the current being interrupted is lower. For instance I'm not terribly worried about turning off breakers at my house given that the current is generally not that high. Though I do get a bit antsy about interrupting the grid tie microinverters when they're pushing hard, and there is no controlled shutdown button in a typical microinverter setup.

 

[Salisburytree]

You turn off your loads first. Then you turn the isolator / breakers. For a hybrid or AIO you turn it off so no loads can be powered. And those loads are on AC so disconnect switches are cheap. Perhaps a DC-rated switch (that doesn't have breaker or isolator functionality in it) can be found for less money, and you start by turning those off. And each switch might switch a small fraction of the total current/power so it takes a smaller hit.

I don't recall what equipment you are powering.

I guess another approach is to decrease as much as possible so the current being interrupted is lower. For instance I'm not terribly worried about turning off breakers at my house given that the current is generally not that high. Though I do get a bit antsy about interrupting the grid tie microinverters when they're pushing hard, and there is no controlled shutdown button in a typical microinverter setup.

I'm all DC loads pulling a max of 50 watts at any given time, all low power water pumps, light and element. My loads will all be individually switched so I can shut them off with ease.

My biggest current would be from the mppt to batteries at 60amp I believe.

Solar panels at around 11amp I believe.

A DC switch does not function in the same way as a breaker I'm reading from that, I need to go do some research of the mechanics of a switch as opposed to a breaker.

 

[SamDeleted]

A DC switch does not function in the same way as a breaker I'm reading from that, I need to go do some research of the mechanics of a switch as opposed to a breaker.

Breakers protect the cable from carrying too many amps, to stop the cable overheating/burning

switches turn on and off lol


So you could do a fuse say 20amp , like this mc4 fuse, (easy to install) And then an isolator

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this would be absolutely fine as an isolator, it's cheaper - not great quality, but you're not going to be switching the solar on and off a lot, hardly ever. . Good value for money .

32A 2 POLE/4 POLE 1000VDC IP66 SOLAR/PV - TRUE DC ENCLOSED ROTARY ISOLATOR | eBay

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[zanydroid]

90%+ of the time you should just be flipping the DC switches.

If you arc and kill a DC switch, or otherwise wear them out, you still have your breakers/other disconnect available to isolate the system and replace that switch. Better that switch take one for the team, than wearing out your breakers/disconnects by using those all the time for switching.

 

[SamDeleted]

I'm all DC loads pulling a max of 50 watts at any given time, all low power water pumps, light and element. My loads will all be individually switched so I can shut them off with ease

Looks like you're going to have plenty of excess power with those 2 panels you're going for, at least in summer.

In a good sunny spot you can expect 5x rated capacity a day average in summer (760w X 5 = 3.8kw), 1x rated capacity in winter (760w)


50w load X 24hrs = 1.2kwh (very rough guess I bet you're using less than that)


that's a least 2 KW spare power, if you got an inverter could be used for other loads . For instance that's enough to run a house fridge & freezer totally off grid all summer. Or boil a full kettle 10 times a day

 

[Salisburytree]

Looks like you're going to have plenty of excess power with those 2 panels you're going for, at least in summer.

In a good sunny spot you can expect 5x rated capacity a day average in summer (760w X 5 = 3.8kw), 1x rated capacity in winter (760w)


50w load X 24hrs = 1.2kwh (very rough guess I bet you're using less than that)


that's a least 2 KW spare power, if you got an inverter could be used for other loads . For instance that's enough to run a house fridge & freezer totally off grid all summer. Or boil a full kettle 10 times a day

These resting are just to get me through winter. I will load up with the garden water feature and possibly the garden room. Fans will also be running alot more during the summer and they are switchable meaning I can turn them up a setting, more juice more blowy!

Or I might just boil a kettle ten times for the pleasure.

 

[Salisburytree]

Breakers protect the cable from carrying too many amps, to stop the cable overheating/burning

switches turn on and off lol


So you could do a fuse say 20amp , like this mc4 fuse, (easy to install) And then an isolator

10A 15A 20A 30A Solar Panel Fuse Connector Fuseholder compatible with MC4 | eBay

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this would be absolutely fine as an isolator, it's cheaper - not great quality, but you're not going to be switching the solar on and off a lot, hardly ever. . Good value for money .

32A 2 POLE/4 POLE 1000VDC IP66 SOLAR/PV - TRUE DC ENCLOSED ROTARY ISOLATOR | eBay

— IP66 water proof with UV resistance. |1x DC Isolator. For isolation the PV array during system installation or any maintenance. — 2 poles, 4 poles available for single and double string.

www.ebay.co.uk

I have been looking at those inline fuses, nice and simple for dealing with the panel to mppt.

If I'm hardly switching it off then I may aswell use the breaker ?

 

[Salisburytree]

ok so im hearing i should leave the breakers alone.

So as far as I get it with some questionable points, the setup should look a little something like this...

Panel - fuse 20a - isolator 20-30a - mppt - fuse 80-100a - isolator? - battery - fuse unknown amps - future inverter - fuse? - load.

Mppt load output - fuse? - cable splitter 1 to 3 cables - 4 switches - loads (pump, light, pump, fan.

 

[SamDeleted]

ok so im hearing i should leave the breakers alone.

So as far as I get it with some questionable points, the setup should look a little something like this...

Panel - fuse 20a - isolator 20-30a - mppt - fuse 80-100a - isolator? - battery - fuse unknown amps - future inverter - fuse? - load.

Mppt load output - fuse? - cable splitter 1 to 3 cables - 4 switches - loads (pump, light, pump, fan.

You've got it


Basically fuse everything lol



For the future inverter, on the 240v output side, anything you plug into it will be fused in the plug (3amp/5amp/13amp).

But you might want to think about also fitting an RCD , RCDs are different to normal breakers. They are there to stop you getting a shock if the worst should happen,

they measure the current difference between the live and neutral (which should be exactly the same) . If there is an imbalance, that means the current is going somewhere else, (probably buzzing through you lol) they will trip and hopefully save your life

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[Salisburytree]

You've got it


Basically fuse everything lol



For the future inverter, on the 240v output side, anything you plug into it will be fused in the plug (3amp/5amp/13amp).

But you might want to think about also fitting an RCD , RCDs are different to normal breakers. They are there to stop you getting a shock if the worst should happen,

they measure the current difference between the live and neutral (which should be exactly the same) . If there is an imbalance, that means the current is going somewhere else, (probably buzzing through you lol) they will trip and hopefully save your life

Masterplug 13A Fused Plug-Through Active RCD Adaptor - Screwfix

Order online at Screwfix.com. Added protection against electric shock. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

Okay I get the message fuse everything! ? should I need to worry about fusing my neutral cables?

Looks like today is fuse shopping day

 

[Salisburytree]

Careful which EPever MPPT you buy, some of them are only 100v max input, which is too low for two of those panels in series,

With the 100v model you'd have to run the panels in parallel (which is doable)
View attachment 139383

Epever MPPT tracer manual

The manual says you'll need 16mm² cable between the mppt to your batteries:

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The 16mm cable is rated at 110amp I won't loose any power with cable this size would I?

I know I need to keep my cables as short as possible to reduce voltage drop so im thinking that might apply to to cable diameter, more copper than required ?

 

[SamDeleted]

Okay I get the measure fuse everything! ? should I need to worry about fusing my neutral cables?

Looks like today is fuse shopping day

1 fuse per circuit, generally on the pos side

The 16mm cable is rated at 110amp I won't loose any power with cable this size would I?

I know I need to keep my cables as short as possible to reduce voltage drop so im thinking that might apply to to cable diameter, more copper than required ?

It's 110amp MAX , not minimum.

As far as I know, too thicker cable won't cause any issues, it's too thin that's the problem.

Also it's about the length of the cable , so whether it's 16mm2 or 35mm2 , the power still has to travel the same distance. Thicker cable gives less voltage drop

 

[Salisburytree]

1 fuse per circuit, generally on the pos side



It's 110amp MAX , not minimum.

As far as I know, too thicker cable won't cause any issues, it's too thin that's the problem.

Also it's about the length of the cable , so whether it's 16mm2 or 35mm2 , the power still has to travel the same distance. Thicker cable gives less voltage drop

Thank you, thats now on its way. Hopefully get this show on the road in the coming week.

 

[SamDeleted]

Thank you, thats now on its way. Hopefully get this show on the road in the coming week.

Looking forward to pics

 

[Salisburytree]

Could I please as for a recommendation on an isolator around 80 amps from my mppt to my batteries. Iv managed to find a 32a isolator for solar to mppt at £25-30 which I'm happy with, however my search results for an 80amp are all in the area of £150-200 , am I looking in the wrong place? ?

 

[Salisburytree]

Of course as soon as I post that message I find something ?

Its from voltracon energy but I see no reviews

 

[SamDeleted]

Of course as soon as I post that message I find something ?

Its from voltracon energy but I see no reviews

I've got one of them, its ok, not great quality but will do the job

You can get them cheaper off brand on Amazon / eBay, it's the same one without the voltracon brand .



I use these 100amp main house switches

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Not DC rated so technically should not be using them , but always worked fine for me

 

[Salisburytree]

Looking at the inside of that im not sure how that would even stop an arc of 60+ amps?!

A thought came to mind, I should always isolate my panels before my batteries to save damage to the mppt. So by bearing that im mind and wanting to stop power from my mppt to the batteries, step one.. turn the solar isolator off. Now correct me if I'm wrong but we won't be having any power enter the mppt so there for none going to the battery.

Am I dumb or does this not seem like a pointless switch after iv isolated the source of power?

 

[SamDeleted]

Looking at the inside of that im not sure how that would even stop an arc of 60+ amps?!

A thought came to mind, I should always isolate my panels before my batteries to save damage to the mppt. So by bearing that im mind and wanting to stop power from my mppt to the batteries, step one.. turn the solar isolator off. Now correct me if I'm wrong but we won't be having any power enter the mppt so there for none going to the battery.

Am I dumb or does this not seem like a pointless switch after iv isolated the source of power?

Other way around, isolate solar input is first. Then battery second

When the load comes off the solar panels their voltage goes up (open circuit voltage) and can overwhelm the mppt, that's why it's always solar first

 

[SamDeleted]

Looking at the inside of that im not sure how that would even stop an arc of 60+ amps?!

It's ok cause it's 12vdc. , 12v does not arc big. Higher the volts , bigger the arc

Am I dumb or does this not seem like a pointless switch after iv isolated the source of power?

I often don't bother with an isolator between the mppt > battery .

It's probs best to have one ,

without isolator you get a few sparks as you make the final connection (generally harmless but does make for quite the crack & light show)