Additional 6.5kW battery on order
@allyfish - what's the function of the two black rotary isolators at the top?
Have you had that DC MCB installed yet?
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- @transparent black isolators are DC solar PV isolators, two strings, one 4 panel, one 5 panel. I await the DC MCB from L R Renewables by Mail and a date when they will install….
That's interesting @allyfish.
I'm puzzled how a 'knife switch' mechanism can be used effectively with high-voltage DC.
When the circuit is broken by rotating the disc, I would expect the resulting arc to damage the edge of the blade.
Any chance of a close-up photo so we can see the manufacturer and model number of those rotary switches?
For others who are following this, and would like a bit more technical insight...
A typical solar array of rooftop panels in series will be supplying the string inverter with a voltage between 150-500v, with a current of less than 20A.
There are DC-rated MCB-style trips which can be used to handle these voltages.
They have a series of plates arranged as a ladder-network which dissipate the arc.
Such a DC trip uses a pair of magnets either side of the contacts to pull the arc into the ladder when the contacts open.
That's why a DC trip is marked with + and - symbols which tell you which way around it must be connected.
There is no 'standard' for this.
You have to look at each unit to check the polarity.
I do have a rotary isolator on the input to the inverters to comply with the safety guidance, but it is preceded by a DC-trip and a pair of fuses.
The trip is opened first, before I turn the isolator.
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@transparent they are Craig and Derricott EPV252 25A 2 pole rotary isolators. Designed for DC voltage and Solar PV isolation, 25A @ 800V. https://craigandderricott.co.uk/product/photovoltaic-pv-enclosed-switchgear/
That's neat.
And good to see that Messrs Craig and Derricott is a UK company, based in Walsall. 😎
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