Our Linky meter display can show various things such as the amount of power being used in real time, and the max power that was used since it was last 00.01hrs. However, it is plain that the two figures do not seem to correlate to one another which seems rather odd.
Perhaps it’s not important but it does intrigue me.
For example, in the mid morning it will say that the amount of power being used is around 350VA (which I assume is their way of saying Watts), and that the max amount of power that was used at any one time since midnight is around 4000VA. Now if I turn on sufficient appliances to create a real time consumption of say 7000VA, the max power used figure only increases very slowly. After using 7000VA for say 5 minutes continuously, the max power since midnight may have slowly increased to around 4800 / 5000VA. So I turn the extra consumption off so that the real time figure is back at 350VA, and the max load figure stops increasing.
So I’m wondering why the Max Power since midnight figure is so inaccurate ?
I mean, it will say around 5000 when I know that it has really been at least 7000 which makes the max power figure since midnight really quite meaningless.
Does anyone know if all the Linkys do this or is ours ‘special’ ?
VA and Watts aren’t the same in an AC circuit as there’s a power factor correction for inductive loads. You’d need to know the power factor of each piece of equipment to calculate the individual VA and then get the total for all. Though I’m not sure that really helps answer your question.
That’s interesting, but I suppose my real question is how can the instantaneous reading for the power being used be so wildly different (higher) from the figure for the maximum amount of power used at any one time since the last time it was midnight.
Interesting - sounds like it is an average rather than max power.
As @JohnH says VA and Watts are only the same thing for resistive loads.
According to the info that came with the Linky it says that it is supposed to be an indication of the maximum amount of power used at any one time since the last time it was midnight.
I noticed this evening that the little green light was flashing quite quickly and upon investigation found that we were using about 4700VA at that moment, but the Max Power drawn figure was just over 3200 so both figures can’t be right at the same time.
As a matter of interest, is VA more or less than Watts, and if so, by roughly how much ?
VA & Watts are the same if the power factor is 1.
However, if there are devices that drag the power factor down (lagging power factor) then Watts will be lower than VA e.g. a 100W demand by a device that has 0,8 power factor = 80 Watts.
There are two quantities - real power and apparent power, power factor is real power divided by apparent power.
The two are equal when driving a resistive load so Real Pwr = Apparent Pwr and PF = 1.0
For a simple resistive load, voltage and current follow Ohm’s law (V=IR), although the voltage (and hence current) varies depending on where you are in the mains AC cycle they are always in step - i.e. V is always equal to current times resistance. If you multiply the average voltage by the average current you get the average power, simples.
If you made lots of individual voltage and current measurements throughout the mains cycle multiplied them together and averaged the result it would be the same number - again, simples.
It gets interesting when driving an inductive or capacitive load as the voltage and current no longer follow the simple Ohm’s law relationship and the voltage and current waveforms occur at different times - either current leads voltage - i.e the peak current occurs earlier in the cycle than peak voltage when driving a capacitive load or voltage leads current when driving an inductive load. Or you can swap it round and say voltage lags current for capacitive loads and current lags voltage for an inductive load.
That means if you measure the average voltage and measure the average current and multiply them you get one value - the VA (volts times amps) number.
BUT if you sampled the instantaneous values for voltage and current throughout the cycle and averaged all of those readings you would get a lower number - this is the “real” amount of power the device is consuming.
Old style revolving wheel and dials meters measured real power consumption, as did early electronic meters. Linky meters are at least capable of measuring apparent power.
Why is this important - well, your kettle, or chauffe-eau has a PF of 1.0 but electronic devices don’t because they are stuffed full of inductors and capacitors and have power factors which are significantly lower than unity. The difference between real and apparent power becomes important for the energy supply companies because it causes extra heating and energy loss in their transformer windings and power lines and until recently they could not charge you for it.
It’s why large industrial users often need big power factor correction capacitors (the usual problem for industrial users being large motors and fluorescent lighting which are inductive loads) because their supply contracts will insist they keep their power factors as close to unity as possible
With the advent of the Linky the energy suppliers can measure and charge for apparent power usage - I don’t know if they are doing so yet but they would certainly like to.
Seems to me that as the Linky displays consumption as VA, then the likelihood is that sooner or later we will all start being charged for KVAhrs instead of KWhrs as at present.
If there was no intent to change the billing structure in the future, there would be no point in having the meters display VA instead of Watts.
If billed consumption were to be switched to VA, then from what I understand of the above somewhat technical posts, those consumers who use a lot of electronic devices will end up paying more than at present. The conclusion would seem to be that the interconnected, smartphone controlled home, will become more expensive to run as and when billing is switched to measuring consumption by VA rather than Watts, conveniently enabled by the way in which the Linky is configured.
That is exactly the point - in, say, the mid 20th century the preponderance of domestic loads would be resistive but as we have more and more electronic devices, and LED lighting (some cheap LED lights have power factors of 50% or less) the average domestic PF is less than unity (how much I don’t know but looking at the UPS which is supplying the computers and monitors I see an apparent load of 210W vs a real load of 190W so a PF of 0.9).
Possibly domestic power factor correction boxes will become a thing rather than a scam.
All the more reason to try and go solar and battery if the property allows and lower the silly french rules on how much you can have as solar if its on the ground or in the air.
Unfortunately solar, and indeed external insulation, is impossible for us as well as anyone else who lives within 500 metres of a church, simply because the ABF will not allow it on the grounds of “La Tradition”.
So it is the old buildings, the one’s that need it the most, that are actively prevented from being modernised.
Daft isnt it, hopefully there will become a time when sense prevails.
I just checked via google earth and we are only 350m from the chateau and church so I will keep my solar panel out of eye shot, I wonder if they would prevent me putting solar thermal tubes on a low level roof.
We are less than 500m ftom a church and have solar panels on the roof that were approved, twice as it happens as it was done in two phases. There are several other solar installations in the village, one less than 100m from the church. Is this a local restriction for you !
A freind of mine asked the ABF if he can install SP on one of his barns roofs. The ABF came back with yes but they must be terracotta red.
Good to know and restores some hope
I’ve seen such an option, but there’s a bit less choice in terms of manufacture.
Hopefully this barn already has terracotta tiles? If not it’s a bit nonsensical 
The roof has pretty much bog standard burgundy tiles for the area they’re much like Kent pegs.
He’s a heating engineer & electrician that likes playing with different heating systems, I’ve never seen so many types of installation in one house, solar, wood burner central with thermal holding tanks, oil, PAC air to water. Just need to turn off one & the by-pass valves to switch from one or another other. The only thing missing is geothermal given the location would be ideal.
Thinking about today’s and latter day engineers, from childhood, maybe we haven’t stopped playing to find out how things work by taking them apart & rebuilding & trying to better them. It works, why does it work? It doesn’t work now I’ve made it better? Why? 
When it comes to what the ABF will or will not approve, it seems to come down to the personal opinion of their representative who covers the area where one resides. In our area the guy is just an intransigent stick in the mud who will not approve any change to anything anywhere near the church as he claims that such modern things as external insulation, solar panels, and heat pumps would disturb the architectural harmony of the area. I had an appointment to see him arranged by the Community of Communes and was bluntly told that the answer was ‘No’ and would remain ‘No’, and that he did not wish to hear anything that I might wish to say about the matter. He then declared the meeting to be at an end and told me to leave !
The Community of Communes is just as bad as they insist that if a house is painted, then it must be Ton Pierre. No exceptions anywhere whether it is near the church or not.
So all in all I suppose that it is fortunate that I can afford to keep using my oil fired heating in winter and buying in electricity for the mobile AC units in summer, and the GES emissions will just have to stay as they are.
So true Robert, for the UK as well, there are the books of guidance and then the personal beliefs of the one you meet. Had a great DS (district surveyor) who would not let me mix two different staircase regs in my case but did take a view and offered a suggestion they would accept. Problem with the old buildings lot is they have too much input. Why cant you have green technology living next door to a drafty old church which never had a heating system. Near me in the UK churches often have solar panels and gods very pleased.