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Solar in a power cut question
Hi, just had solar panels connected, understand that it is grid tied and solar panels won’t supply house directly in outages, wondering if one was to switch all mains off via fuse box would then the solar panels production be able to be used directly? Thinking it wouldn’t be a safety issue with the grid, or does the system close everything down entirely until grid power is back on? Many thanks for info on this.
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11 Replies
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The inverters normally power down if no grid voltage is detected, unless they have island mode/ emergency power setup
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No earth!
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Nonsense … when you disconnect the grid via the normal DNO supplied isolator, it disconnects the live and neutral, not the earth. disconnection of the earth can only occur in a PEN fault situation. He specifically asked “wondering if one was to switch all mains off via fuse box” … the earth woudl still be present. The correct answer is that grid tied inverters have to shut off within 5 seconds of loss of grid and must not repower for 30 seconds after connection of grid.
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Grid tied inverters need to “see” the grid or they will shut down.
The way around it is to create an entirely separate circuit, with a separate earth circuit, that will either manually or automatically switch over in the case of a power cut.
You say just solar panels, so don’t expect much to happen if there’s a power cut when the sun isn’t shining, not worth the expense of installing. If you have batteries, then it makes sense but don’t have everything on that circuit as it may not power your house for long.
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They’ll normally only work in island mode if designed and installed like that. Amongst other reasons, see Eddie’s reply above.
Plus, your vacuum cleaner would go off if the sun went behind a cloud.
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I had an electrician install a separate earth rod and fusebox connected to the inverters AC Backup socket. I’ve a live double socket that runs off the batteries in the event of a power cut. I expect it would power a couple of lights, Router, TV and combi boiler.
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Octopus did my installation and not only refused to install any sort of backup, but said that, if a third party installed one, it would invalidate my warranty.
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Solar panels generate DC current and everything in your home requires AC current- even if it then has a built in rectifier to turn it back into DC.
Therefore all solar generated electricity requires an inverter to change the DC from the panels into AC. there are off grid inverters that don’t require to be connected to a grid supply to work but we’re not allowed to use an off grid system without the protection of “islanding.”
Islanding provides isolation of the inverter and house from the grid so that power can’t flow back into it thereby causing danger and damage to engineers who are working on it and feeding power to your neighbours.
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No , under G98 / G99 type approval any grid tied inverter has to shut down AC grid connected port , and thus grid supply, within 5 seconds of loss of the grid supply signal max.
You need to have a whole house backup supply wired to the EPS port (if you have this) and a changeover switch.
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There are legal regulations regarding solar panels not providing outages without a safe design.
They are there to protect engineers working on repairing outages who need to be able to turn off any source of energy generation.
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If you want power when there an outage you need a “gateway” that also has an earth spike as part of the install.
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