solar pv question on meters

hi

when i am generating 3kwh via the solar panels and only using to 2kwh the red light on the meter (electric company bill) comes on which means it has stopped..

but if i am generating 1.5kwh and using 2.00kwh will my meter which the electric company bill me for only going up 0.5kwh or 2.00kwh as no red light on the meter is visible in this scenario


i hope this makes sense :yes:

It should only go up 0.5 kWh. The electricity generated by your PV in this scenario never goes through that meter. It goes straight from your inverter to whatever is using it.

Assuming we are talking about an installtion in the UK, uner the FiT schem, then so long as it has been wired in correctly TedM is spot on.

Though of course we should actually be talking Power (kW) not energy (kWh) here. you billing is dependant upon the time of use. (Power x Time = Energy)

If you generate 3kWh (Energy) during the day and use 2kWh (Energy) at night them you will be billed for 2 kWh and (assuming you are on FiT scheme for <30kW) you be paid for generating 3kWh and additionally paid for exporting 1.5kWh (as they don't measure it)

IF you are generating 3kW (power) and at the same time using 2kW (power) in lighting etc, and it generates consistently at that level for an hour, and your consumption doesn't change during that period (no extra cups of tea ) then DURING THAT HOUR your import (DNO / Electric Company ) meter should not change

IF you are generating 1.5kW (power) and at the same time using 2kW (power) in lighting etc, and it generates consistently at that levvel for an hour, and your consumption doesn't change during that period (no extra cups of tea ) then DURING THAT HOUR your import (DNO / Electric Company ) meter should only increment by 0.5kWh - [0.5 kW (Power) for an hour = 0.5kWh [Energy])

In this graph, the only time that the electric company meter would be increasing is when the RED line is above the GREEN line (and hence the only time you would be charged)



The RED line (consumption) as been optimised to match the GREEN line (Generation) in this real life installtion by the installtion of an ImmerSun unit that closely tracks the generation and consumption and diverts excess generated power to an electric hot water immersion heater. The large peaks include lunchtime when the kettle went on , breakfast and supper time.