Tuesday, 5 November 2013

Turning Solar PV Panels Off.

    Mr Mainwaring

It might sound ridiculous, but there will be times when you don't want the solar PV panels on your roof to generate electricity...


Sometimes, it may be because like me, you need to remove the panels from your roof because it needs repair
More importantly, in an emergency situation, fire, structural damage, etc, you may need to isolate the power being generated and prevent it from entering your house or the mains grid.





The usual disclaimers here. Electricity is dangerous. Isolate and switch off all equipment before proceeding. If you're not certain about what you're doing. DON'T.


Every system is different, but they ALL should have at least three isolating switches.

1: DC isolating switch for the power coming from your panels. 

2: AC isolating switch for the power coming from your inverter.
3: A miniature circuit breaker (probably located next to your existing fuse boxes) isolating your internal wiring from the electricity generated from your roof.



Here's the IMPORTANT bit to remember....



It doesn't matter which switches you turn off at ground level, the PV panels on your roof are LIVE, producing volts and amps that could kill you, your family and the emergency services if not treated with respect.

Even after you've turned off all the switches, the panels are ONThey are always ON during the day, covering them won't turn them off, being covered with snow won't turn them off.


I would even be wary in the blackest of blackest nights in assuming they're off. Each panel retains an electric charge which if allowed to earth itself and may damage itself and more importantly.YOU.

The company who installed my system (who seemed so solid and safe) before going into liquidation 18 months later! did in fairness do a very professional job. All of the wiring and control switches are clearly marked and inside the door of the control cupboard is a schematic diagram of what does what.



Full system shut down can be achieved by the following
sequence:

1: Turn main AC rotary isolator to the off position
 and lock off (located next to the consumer unit)
2: Switch off the PV circuit trip switch at the consumer
 unit or on separate unit


3: Turn second AC rotary isolator to the off position
 (located next to the inverter).
4: Turn DC isolator to the off position
 (located next to the inverter).


All of the above sounds alarming. However, PV systems correctly installed are very safe. They rarely need any maintenance and in the event of a malfunction or power-cut they automatically turn themselves off. 
If engineers are working on your supply cables and have turned your power off, they won't come to any harm from your property as the inverter will have automatically detected the loss of mains grid electricity and turned itself off. The good news is that once the power is restored from the grid the system will boot itself back on and in approximately 3 minutes you'll be earning money and generating to the grid again.
Assuming its daylight.

As you know the unwritten law of emergencies states "problems happen in the dark and during poor weather."
Even though it's probably never going to happen I'd take a look at your systems switches whilst it's light and not pouring with rain. I'd rather spend 5 minutes being prepared, rather than 30 minutes panicking about where I put the instructions during a crisis.

Good luck.


Icarus 
Twitter: (@solaricarus)

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