Disputed bills after solar installation

Scot_39

Naive question

do solar systems not measure generation and export seperately then for tgeir own reporting - I thought id seen reference to both in past ?

laidbackgjr

https://forums.moneysavingexpert.com/discussion/comment/81972326#Comment_81972326

They do, but not with the precision of a meter and therefore can't be used for billing.

QrizB

do solar systems not measure generation and export seperately then for tgeir own reporting - I thought id seen reference to both in past ?

Generally no.

Typically a system will be installed with a total generation meter, formerly used for FIT payments and still required by the official guidance on such things. This will go between the inverter and the consumer unit. (Systems with a DC-side battery will usually fit a bidirectional generation meter, since charging the battery from AC will mean current flowing the wrong way through the generation meter.)

An export meter needs to go between the consumer unit and the grid, which is where the import meter is. The most common way to measure export is by using the export register of a smart meter, as boths SMETS standards have required one.

Reed_Richards

https://forums.moneysavingexpert.com/discussion/comment/81972326#Comment_81972326

My solar system, installed in 2019 under the old FiT scheme, has a generation meter but no export meter. However the inverter monitors the incoming and outgoing power and stores this information online so I can see my export on any previous day, week, or month. This data won't be as accurate as if it were measured by a smart meter because readings are only taken periodically; once a minute I think, and as an average over that last minute. But it's a lot better than just using an estimate. I have no idea if many other solar systems do this.

Scot_39

So seems some might have a crude export estimate - otthers not.

The OP in post refers only to total generation meter.

QrizB

So seems some might have a crude export estimate - otthers not.

Hybrid inverters (used with DC-side batteries) need to sense the household power demand (so they can balance it) and so usually have a current clamp in the incoming supply. This means it's fairly easy for them to give an estimate of the total energy imported over a period. RR has one of these.

Regular inverters (no battery) don't need this and it's not generally implemented.

The OP in post refers only to total generation meter.

OP hasn't mentioned a battery so I suspect they don't have a hybrid inverter.

Reed_Richards

Hybrid inverters (used with DC-side batteries) need to sense the household power demand (so they can balance it) and so usually have a current clamp in the incoming supply. This means it's fairly easy for them to give an estimate of the total energy imported over a period. RR has one of these.

Yes indeed, I have a hybrid inverter. But the current clamp can't be vey expensive; it's a pity that these are not routinely installed (as I now learn).