Green Building Forum - Difference in generation between inverter and generation meter Thu, 16 Apr 2026 18:48:05 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277453#Comment_277453 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277453#Comment_277453 Wed, 18 Dec 2019 12:48:52 +0000 richardelliot
The meter is one of these (I'm pretty sure):
https://www.pluginsolar.co.uk/?product=geo-solo-iii-wireless-pv-monitor-and-meter

Has anyone else noticed anything similar on their systems? Any ideas what I might be able to do about it?

I don't earn a lot in FIT tariffs so there is no point me spending a lot of money to resolve the issue, but I was curious to know if anyone else has had a problem. The company who installed the system is no longer trading so I won't be able to get them back to take a look at it unfortunately.

Thanks,
Richard]]> Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277454#Comment_277454 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277454#Comment_277454 Wed, 18 Dec 2019 13:06:25 +0000 owlman Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277455#Comment_277455 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277455#Comment_277455 Wed, 18 Dec 2019 13:18:40 +0000 richardelliot
Posted By: owlmanFrom my experience none of them are perfectly synchronised. I have two arrays and two gen. meters and neither read the same as the inverters; Just submit the gen meter reading.
]]> Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277457#Comment_277457 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277457#Comment_277457 Wed, 18 Dec 2019 14:23:23 +0000 bhommels I usually apply a blanket correction factor, determined from the data. This is not entirely accurate as the difference gets relatively larger at lower power levels. The more accurate your data is, the more you can play around with trying to deconvolute all kinds of subtle effects. Not really worth it in my opinion..]]> Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277459#Comment_277459 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277459#Comment_277459 Wed, 18 Dec 2019 15:44:16 +0000 dimengineer It is a bit of modern thing - we "expect" our meters to be "accurate" - and when they aren't it upsets us.]]> Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277460#Comment_277460 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277460#Comment_277460 Wed, 18 Dec 2019 15:59:09 +0000 LF In industry I always expect an inverter to use about 3% power (minimum)]]> Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277462#Comment_277462 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277462#Comment_277462 Wed, 18 Dec 2019 18:28:44 +0000 Mikel
"Nominal power of the PV system: 3.8 kW (crystalline silicon)
Estimated losses due to temperature: 7.7% (using local ambient temperature)
Estimated loss due to angular reflectance effects: 3.2%
Other losses (cables, inverter etc.): 14.0%
Combined PV system losses: 23.1%"

The average difference between my datalogger on the inverter and the generation meter is 3.6-3.8% lower on the generation meter.

Today, when the weather has been appalling the generation meter read 0.1 kWh and the datalogger 0.360 kWh.

So, similar to the others here!]]> Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277475#Comment_277475 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277475#Comment_277475 Thu, 19 Dec 2019 17:56:28 +0000 CWatters https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/454144/Electricity_Determination_Report_2003-2014.pdf

Selected quotes:

National Measurement& Regulation Office
Electricity Meters - Disputed Meter Accuracy Report June 2015

3.1 The limits of meter accuracy for meters approved under GB national legislation are prescribed in The Meters (Certification) Regulations (SI 1998/1566)4. Unlike most other countries, there is no additional tolerance for electricity meters operating in-service and they are required to maintain the same limits of accuracy as when new.

3.2 Electricity meters are considered “accurate” if the permitted margins of error do not exceed +2.5% to -3.5% throughout the entire load range at which the meter is designed to operate.

3.3 For MID meters the limits of accuracy at reference conditions are derived from the harmonised standard BS EN 50470-3:2006. The accuracy tests take into account the additional errors due to variation of influence conditions. However there are relatively few MID electricity meters installed in GB and, to date, only a handful have been submitted for determination.

MID Accuracy Class Maximum Permissible Error Limits

Electricity Meters (Class A)
±2.5% at minimum current flow;
±2.0% at one fifth of maximum current flow; and
±2.0% at the maximum current flow.

Electricity Meters (Class B)
±1.5% at minimum current flow;
±1.0% at one fifth of maximum current flow; and
±1.0% at the maximum current flow.

Electricity Meters (Class C)
±1.0% at both minimum current flow;
±0.5% at one fifth of maximum current flow; and
±0.5% at the maximum current flow.

end quotes.

So a meter approved to the EU/EN standard might be more accurate then the GB standard meter.]]> Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277479#Comment_277479 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277479#Comment_277479 Thu, 19 Dec 2019 20:28:11 +0000 bxman
If you do a search for " performance curves of Grid tied inverters" you will find that at this time of year most of the day most of the solar input is simply powering the inverter itself .

Your GEO Solo Monitor will be nowhere as accurate as the Feed-in Generation Meter
that will not be your generation meter .

There will be an approved meter fitted somewhere what do you take the readings from when you submit them to EDF.]]> Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277482#Comment_277482 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277482#Comment_277482 Thu, 19 Dec 2019 23:46:37 +0000 Jeff B
Like Mikel's observation above, the weather is so gloomy here at the moment (west Wales), we have had three days in a row with zero PV output. This has never happened before in the 8 years we have had our PV system!]]> Difference in generation between inverter and generation meter https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277502#Comment_277502 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16365&Focus=277502#Comment_277502 Fri, 20 Dec 2019 23:35:00 +0000 Jeff B