Net, Gross = Confused!


#1

Is there a simple primer somewhere that explains the difference between net and gross? I’m trying to get my solar data uploaded but can’t seem to get the right combination of settings to get the lovely graphs everyone else has!!

Basically I have a clamp on my meter which gives me live power in or out (+ve meaning import, -ve meaning export). I also have a clamp on my solar which is always +ve when generating).

So my generation is from the solar clamp, that seems simple enough.
My consumption is mains clamp + solar clamp
If my mains clamp is < 0 then I’m exporting, if its > 0 I’m importing

But how do I plug that all in to v2 and v4??? Do I need to do the calcs and send the results or does pvoutput do the calcs for me?

I’ve scoured the help and still confused… any help would be greatly appreciated!!!


#2

If we take the following scenario -

Solar clamp = 1500w (i.e. generating 1500w)
Mains clamp = -1000w (i.e. exporting 1000w)

v2=Generation
v4=Consumption

From the help guide for addstatus.jsp if using “Net” model -
v2 = Positive or zero and v4 = Less than zero Export = v2 + (v4 * -1) Import = 0

… but in this instance export is not v2+(v4*-1), export is simply v4*-1.
i.e. using net model export would be 1500+(-1000*-1) = 2500w but export is simply (-1000*-1) = 1000w with house consumption at 500w.


#3

To get the formula, Use the following: V2 = generation. Since V4 is mains, I’ll assume V2 is tied to the mains panel, then V4 really is net. Try either V4 = (V4-V2) or V4 = (V4+V2) assuming that the V4 clamp is actually measuring net instead of consumption. If net = consumption+/-generation. Solving for consumption: consumption = Net +/- generation. Whether the value is +/- depends how your system views consumption vs net as positive or negative numbers. I had to change my formula from (+) to (-) to effect the correct curve.


#4

Cheers @gregvet - I think I’ve got it cracked now… will keep an eye on it over the next few days.


#5

Just checked your system. Looks like it is graphing correctly.


#6

Yes… for some reason the API didn’t seem to like me sending net=1, I guess because my model is set to ‘UK Gross’. Sending net=0 seems to have made it happier.

I’ve also calculated consumption my side before submitting.

Thanks again.


#7

Note that the parameter for sending net data is n=1


#8

Yep, typo there on my part!! Thanks