Hi all,
Further to my info about import/export meters being fitted in the "secondary generation meter" position (between the inverter AC output and the CU) I now have final clarification from Landis & Gyr as to how their 5235 Import/Export meter is intended to be installed and used.
Firstly, my embarrassed apologies for any confusion - I've had numerous discussions with L&G directly about this and it seems that the most recent advice I provided is in fact incorrect. Following conversations with Worcester and others, I decided to try to get to the bottom of this once and for all.
Bottom line - an import/export meter fitted as a secondary meter will NOT be able to measure your exported energy OR the amount of your generated energy that the client consumes. It will ONLY be able to measure the generated energy from the PV installation.
The intention is that the import/export configured 5235 meter is to be fitted as a primary meter in order to measure the reverse energy sent back to the DNO/Grid. The secondary generation meter only needs to be an "import-only" meter (standard 5235A or 5235B - or any other meter such as the A100C configured for import-only kWh measurement) but, when combined with an import/export meter in the primary meter position, all necessary measurements can be taken to achieve the total generation tariff AND the export generation tariff.
I have a client whose installer replaced their primary meter with our 5235 import/export meter and fitted a standard 5235B import-only meter in the secondary generation position (measuring total generation from the PV installation). Their DNO now receives total generation data as well as import (from the DNO) and export (to the DNO) data. The client now avails of 100% of the generation tariff as well as the additional 3p/kWh for the export tariff. They are currently not consuming more than 50% of their total generated kWh.
Incidently, when this client spoke to his DNO and told them he wanted a primary Import/Export meter fitted, they said they do not replace for systems under 50kWhp. When asked if he could have one fitted by his installer/qualified electrician, they said to go ahead and send back the old meter.
I'm in the process of updating our website product info now, apologies again for the confusion caused by L&G providing conflicting info.
The issue still remains with regards to monitoring/tracking typical energy usage to decide whether going down the "export tariff" route will be economically beneficial to specific clients but, as far as I can see, most domestic installations where the client property is generating much more than being used during the day, total generation tariff combined with export tariff "should" be a more attractive option than simply 50% paid against total generation.
Lastly, a double-pack of import-only and import/export 5235 meters (to cover secondary and primary meter install positions) will be something that we will promote to installers at a promotional price of around ÂŁ40 depending on volumes - just so you are aware of likely costs.
Any advice/comments welcome,
Andy