Upscaling the solar generation on our property 2

[openspaceman]

I had a look at the manual for your battery inverter and it does look like a screwed eye terminal within the gland cover.

Yes fig 5.17 and 5.18 show screwed terminals so that will be the way to go.

I've got 25mm2 and 35mm2 welding cable so as long as I can find eye lugs that fit in the inverter I'm good to go. If the inverter doesn't like it I can revert.

[openspaceman]

Any suggestions for an isolating switch for my new panels, max open circuit 150V and current 60A?

Screwfix have this one which should be okay indoors

https://www.screwfix.com/p/schneider-el ... o-nc/936hv

or more traditional and IP65

https://www.screwfix.com/p/british-gene ... h-no/8536r

but AC only?

[Stinsy]

Have a look at toolstation: https://www.toolstation.com/search?q=dc%20isolator

Breaking DC is no joke! Be careful using an AC-rated isolator (make sure it is oversized) and even then understand it is sub-optimal...

[Oldgreybeard]

Indeed, breaking DC is seriously different to breaking AC, so under no circumstances should an AC type isolator be used - there is a very good chance that there will just be a humongous arc if the thing is ever turned off under load.

I just bought a 16A Garo DC isolator form my second PV system, from this vendor, for a bit under £25: https://www.ebay.co.uk/itm/154515532703

Garo stuff tends to be reasonably OK as far as I can tell. The spec seems OK, 20A at 500V, 16A at 700V, 9A at 1000V. My second system is only six 400W panels, in one string, so this will be more than adequate.

[openspaceman]

Indeed, breaking DC is seriously different to breaking AC, so under no circumstances should an AC type isolator be used - there is a very good chance that there will just be a humongous arc if the thing is ever turned off under load.

I just bought a 16A Garo DC isolator form my second PV system, from this vendor, for a bit under £25: https://www.ebay.co.uk/itm/154515532703

Garo stuff tends to be reasonably OK as far as I can tell. The spec seems OK, 20A at 500V, 16A at 700V, 9A at 1000V. My second system is only six 400W panels, in one string, so this will be more than adequate.

Thanks Stinsy and OGB I suspected that might be a problem.

The Garo one is 20A at 500 but will it stand 60 A if my panels ever reach their maximum current? i.e. will the mppt charger ever get to exceed the current limit as it gets the best out of the 1500W string

[Stinsy]

I’d definitely size it for the Isc of the setup. You might need to use it to break a circuit under failure conditions!

[Oldgreybeard]

Indeed, breaking DC is seriously different to breaking AC, so under no circumstances should an AC type isolator be used - there is a very good chance that there will just be a humongous arc if the thing is ever turned off under load.

I just bought a 16A Garo DC isolator form my second PV system, from this vendor, for a bit under £25: https://www.ebay.co.uk/itm/154515532703

Garo stuff tends to be reasonably OK as far as I can tell. The spec seems OK, 20A at 500V, 16A at 700V, 9A at 1000V. My second system is only six 400W panels, in one string, so this will be more than adequate.

Thanks Stinsy and OGB I suspected that might be a problem.

The Garo one is 20A at 500 but will it stand 60 A if my panels ever reach their maximum current? i.e. will the mppt charger ever get to exceed the current limit as it gets the best out of the 1500W string

Not sure how the 60A figure has been arrived at. A 1500W string of panels is going to be no more than about 10 to 12A Isc in all probability, depends on the make up of the string. The 400W panels I've just bought have an Isc of just over 10A, so six of them in our 2,400W array are still going to be well within the 16A rating of that Garo isolator. 6 x 49.5Voc = 297V DC maximum, the isolator is rated to handle 20A at that voltage, so will easily handle the 10.12A Isc (although by definition you can never have Isc at the same time as Voc).

[openspaceman]

Not sure how the 60A figure has been arrived at. A 1500W string of panels is going to be no more than about 10 to 12A Isc in all probability, depends on the make up of the string. The 400W panels I've just bought have an Isc of just over 10A, so six of them in our 2,400W array are still going to be well within the 16A rating of that Garo isolator. 6 x 49.5Voc = 297V DC maximum, the isolator is rated to handle 20A at that voltage, so will easily handle the 10.12A Isc (although by definition you can never have Isc at the same time as Voc).

Yes you are right the highest current rating of the panels is 30A not 60A, the charger is my max 60A which is what confused me. I'll go with the slightly larger garo isolator.

[nowty]

Openspaceman, the DC PV isolator is for your 1500W string to go into the charge controller, it will run at circa 100V / 15A maximum.

You will also need a suitable fuse between the Charge Controller and the batteries, the instructions with the charge controller should give the recommended fuse size.

If you also want a DC isolator (I don't bother as I just pull the fuse) between the Charge Controller and the battery you will need a more heavy duty low voltage / high current one like https://www.ebay.co.uk/itm/185506081378 ... BMgLLQwflg

There are also fuses which can act as isolators like, https://www.itstechnologies.shop/produc ... -32-50-vat

[nowty]

Openspaceman, I missed your last post so,

I don't know where your getting that 30A number from either.

Maybe panel fuse rating ?