Solar Panel export query

[robgraham]

This is whether the energy supplier, in my case Scottish Power, will fit an export meter.

The SP website says that they only do so if the power output is greater than 30kW. However it does seem from anecdotal information at the moment that they will do so if the disc type household power meter runs backwards.

Now I would have thought that this would have been an in-built characteristic of this type of meter ?

One of my possible suppliers is plugging a box called an Immersun which effectively intercepts all export power and redirects it to a load within the house - the DHW immersion heater typically - such that I would get the 50% FIT payment but would use potentially all the power generated by the panels. Clearly if there is an export meter, then this black box is not worthwhile.

Rob

[harry]

Sub 4Kw they just assume you are using half of the power yourself. (Difficult to do in practice.). A reversing (Disk) wheel meter is no good because imported and exported/generated power are paid for at different rates.

So you would need an import/export meter or two ordinary meters wired in series but in opposite sense for the current coil.

The modern electronic meters allow reverse power to pass but do not record it. When power is being imported a red light flashes once for every watthour. When power is being exported it remains permanently on.

The meter on your PV panel flashes when you are generating PV power and by night/shutdown is permanently on.

[harry]

You are paid for all power generated whether you use it or not. There are several gadgets to help you use more/all of your power and ensuring you don't accidently use any imported power.

One sort switches an appliance one only when the PV achieves enough power to cover that load. The other puts out only the same power as the PV panel is generating. It does this by reducing the voltage. This means you can only use it on heating loads eg immerion heater.

However both of these are very expensive. If you can switch stuff on and off manually (ie you are present in the middle of the day and alert) Hardly worth the expense. Unless you have a truely massive heat store (eg hot water tank) For heating the building say.

I looked into all this and conclude that it was uneconomic/unworkable.

[BruceB]

Meter going backwards is not a reason that the supplier will have an export meter fitted. If they know your meter goes backwards they will change it (eventually). In my experience they often do not get around to changing it until after the first time you try to submit a negative reading. If yours does go backwards think yourself very lucky.

It is generally a bad idea to have an export meter fitted because you then pay a metering charge of say a few hundred pounds a year for someone to read it occasionally. You need more than 30kW to make that worthwhile over the deemed 50% export tariff.

Immersun is normally very worthwhile in my experience - you get peanuts for exporting the power, except if your meter goes backwards. But as stated above if it goes backwards so much you have negative consumption then the supplier's computer will say "No" and the meter will be changed.

[Andy Burns]

... allow your neighbours to use any of the power you pick their pockets for.

[Brian Gaff]

Would that not depend on what they offer for the electricity against what it costs you to use it from them theough?

Brian

[robgraham]

Thanks guys - what has been said fits in with what had confused me. I went to see a neighbour who had panels fitted in May and allowed myself to get confused by his non technical description of all the comings and goings. In reality it was as has been said - his old meter went backwards, his electricity bill for the quarter was =A317 and they changed his 'disc' meter to an electronic one.

Rob