Solar Power Query ??

firefox1956

Might be a silly question........
If you have solar panels connected to an inverter & the inverter is connected to your household supply but NOT to the national grid what happens to the electricity you produce but do not use ??
Does it build up ( !!! ) somewhere or does the inverter cut out or what ??
Simple answers please .........

lisyloo

This won't happen because you only get paid if you're wired to export so no one would do it.

You could install batteries, but this in in feasible in practice.

firefox1956

I don't want to the panels to be connected to the grid......

Dave_Fowler

firefox1956 wrote: »

I don't want to the panels to be connected to the grid......

Without installing some automatic switchgear, the house supply would have to be disconnect from the grid and you would therefore have to be producing enough power to run your house continuously. You'd need an inverter which was designed to run without a grid connection. If you are producing enough electricity, on average, from your panels you could use a large bank of batteries to supply power whilst the sun isn't shining. For the wintertime you would probably need an alternative source of power - perhaps a petrol/diesel generator.

With an off-grid inverter, the inverter will regulate its output to match the load of the house. The power produced by the panels would not be converted to ac mains if it was not required by the house or the battery bank.

Dave F

SunReader

lisyloo wrote: »

This won't happen because you only get paid if you're wired to export so no one would do it.

Not sure on that, you get paid for the power you generate, not necessarily export. Unless the rules have changed you could waste the power on an electric fire when the sun is shining, and still get paid for the power generated -even if you use it /waste it all yourself.

thenudeone

Unless you specify differently (which involves extra cost and switching apparatus) all solar PV installs will have a "grid-tie" inverter which simply doesn't work if there is no mains supply. Partly as a safety feature, because if it continued to export the power even when the mains was disconnected, an electrical worker working on the "dead" line could be electrocuted by the power your PV system was exporting.

It is possible to have a system which will work without mains, but your electrical system must be disconnected from the mains when that haappens.

lisyloo

Not sure on that, you get paid for the power you generate, not necessarily export

You definitely have to be connected to the grid to be eligible for the EXPORT part of the FIT payment.
I agree that you do not actually have to export anything - mine is "deemed" to export 50% of what is generated - this is partly because on some systems they don't have any way to measure how much is actually exported.

Apparently you can technically get the GENERATION part of the FIT payment, however if the info below is correct and up to date there is a major catch that there are no eligible approved meters for DC systems which means you can't claim it in practice.

http://www.fitariffs.co.uk/faqs/item/333/

Also as above previous post, you leccy does need to be on for the Solar PV to work.

zeupater

firefox1956 wrote: »

Might be a silly question........
If you have solar panels connected to an inverter & the inverter is connected to your household supply but NOT to the national grid what happens to the electricity you produce but do not use ??
Does it build up ( !!! ) somewhere or does the inverter cut out or what ??
Simple answers please .........

Hi

Simple answer ... If you attach the panels (via an inverter) to the household supply and the household supply is connected to the national grid, you are connecting the panels to the national grid.

Now, if what you're describing is an 'off-grid' property you would need to provide some details of what you've currently got and what you're looking at achieving from an 'off-grid' system - then someone could probably provide guidance/help.

Regarding " ... what happens to the electricity you produce but do not use ?? ... Does it build up ( !!! ) somewhere or does the inverter cut out or what ??" .... the full technicalities of what happens would depend on your requirements and therefore how the system is designed, but (and this it where the answer becomes less simple .... ) the basic principle of a solar panel array is that it creates a voltage between the poles and power is drawn from the panels at the level required, up to the maximum available which is constrained by the lighting conditions, the size of array and the performance of the inverter (if one is required) .... the inverter basically converts the DC voltage current to an AC voltage supply to satisfy the demand based on the minimum of (a)demand, (b) the maximum DC available or (c) it's own maximum performance. In a grid tied system the inverter is designed to monitor & match grid conditions, then by raising it's own output voltage marginally above current grid conditions the entire grid becomes a demand, therefore creating a condition where demand is always 100% .... If there's no demand (/load) then there's no current, just a voltage - you can't store volts on their own, just energy (volts x current x time), so there's nothing to be stored in the inverter (apart from a small buffer in the circuitry) ... It's a lot more complex than this but that's effectively the basics in layman's terms, so hope this helps answer the original questions ...

HTH
Z

lisyloo

Simplistically though the volts don't just disappear do they?
Are they just dissipated into the sky as heat?

Dave_Fowler

lisyloo wrote: »

Simplistically though the volts don't just disappear do they?
Are they just dissipated into the sky as heat?

Think of Volts as water pressure. When you turn the tap off, no water flows, no water goes anywhere. The Amps are like water current, you can cut it off at any time by using the switch (tap).

Dave F

firefox1956

Thanks to everybody of their replies.
Perhaps I should have been more specific in my OP.
What I want to do is connect 2 or 3 solar PV panels to an inverter & connect the inverter to a 1 KW immersion heater.
This would be on a property in Spain & for various reasons I do not want to connect to the grid.
So reading the replies above I would need to connect the solar PV panels to an inverter, connect the inverter to the immersion heater but then install an isolating switch to break the connection to the grid when the inverter was turned on ??
In effect when I require water heating I would turn on the inverter & turn off the connection to the grid.