1- If the power data (Watts) you have considers your panels efficiency (I think your power at maximum must be roughly around 200 watt per meter if efficiency is included);

2- And if your panels are actually producing their nominal power;

then simply multiply your power by 0.25 (as your time spans are 15 minutes) the answer is amount of solar energy your panels produce in Wh, repeat the procedure for other time intervals according to their data, then sum all other 15 minutes energy production rates (in Wh) so that it matches your consumption data time span.

Let me know if I didn't get the point.

Regards

You can simply make a graph of power (W) data vs time, than divide the energy data (Wh) by the time interval (in h) they refer to and put the results on the same graph. Hope this answer your question. Regards,

Ennio

https://enphase.com/en-us/support/what-difference-between-watt-and-watt-hour

I agree with Prof. Ennio Macchi. It is the simplest method to plot both wattage measured and watt hour measure in a common scale for clear understanding.

You are trying to relate two different units. One is Power (Watts) and the other is Energy (Wh). These two concepts are adequately explained in Mushtaq Ahmad's link sent, above.

To convert from one to the other you would need a medium (a Resistance, e.g. a motor, a fan etc.) upon which the power flows through for a time duration to get the Wh.

You can plot them on a graph where one axis is the Power in Watts and the other axis is a multiple axes representing what the medium is (again for the motor, or for the fan etc..)

Power is an energy rate i.e. the derivative of energy versus time. Your comparison is as to compare displacement with speed or speed with acceleration or acceleration with jerk.

Since Your data are in Watt (power) the energy [Wh] is the INTEGRAL of power versus time.

Dear powerful and respected Mahamood,

You are going to have the table like this

Time,T (hr) | Power,P (Watts)| Energy,E(Wh)

0. | 0. | 0

0.25. | 2. | 0.5

0.5. | 3.5. | 1.75

Convert each time interval from minutes to hours

Where,

T - the hours of generation of power from the solar panel, hr

P - the instantaneous power generated from the solar panel, Watts or J/s

E- the instantaneous energy generated from the solar panel, Wh

From Power (Watts) = energy generated (J) / time taken (seconds)

Energy generated (J) = Power (Watts) * time taken (1/3600 hr)

Energy generated (Wh) = (Power (Watts) * time taken (hr)) / 3600

For

Power (Watts) = energy generated (Watts mins) / time taken (mins)

Energy generated (Watts mins) = Power (Watts) * time taken (1/60 hr)

Energy generated (Wh) = (Power (Watts) * time taken (hr)) / 60

Best regards,

Kifilideen.

Hello, In which interval is available consumption data?

Simple concept , wh is simply a supply of 1 watt for 1 hour , as mentioned by Ennio Macchi put time on x axis and power and energy on y axis . Regardless, to calculate the generated energy , plot the power graph over the time (15 min ) in your case , then take the integration over this period , (0-15) min ( remember to convert to hours ) then the product is your power in wh .

Thanks for all valuable solutions. I just have to say that the power generated by the solar panels was recorded at fifteen minute intervals. So I assume that the power over that fifteen minute interval is constant at a value P (kW), In reality it is not. How can i estimate the "near to exact" generated power curve ? It might slightly miss the energy export and battery charging energy..

Power (W) = Energy (Wh) / 3600

Mahmood, you can still plot the points ( every 15 min ) then connect them with a direct line , then do the integration over the whole period of time, this will give you the approximation you want.

Dear respected Mahmood,

The less the time interval you used the more accurate the data of the power generated you are going to have. The 15 minutes interval you are using is still OK. To determine the power generated by the solar panel over the period of time i agree with the method given by Dr. Hassan.

Just multiply each value of the PV production which is in Watts by 15/60 to get Wh.

This is simply the:

Energy (Wh) = Power (W) * time (h)

Thank you again. I realise what i did was completely wrong. i.e Converting Solar PV power into kWh then plotting it against time which doesn't make sense. Not only that i plotted load consumption(load meter and grid meter) into kWh on the same plot. So lastly i wanna ask if load consumption is in kWh, then all i have to do is convert in into power and then plot it with Solar PV production (Watts) ?

Yes, just convert the load consumption from kWh to kW by dividing each value by the time interval in hours. Then multiply by 1000 to convert it to W.

Dear Mahmood,

Following the discussion it became evident that your problem was solved by the answers of the colleagues.

But i want to stress that the kwh is an energy unit and the kw or watt is a power unit. The relation is simply:

kwh= integral of the power p in watts over the intended time interval Tdivided by 3600. If the power p is constant with time or if it is an average value pav and the time period is T in seconds, then

kwh= pav T/3600.

Conversely

Pav in watt per second = kwh x3600/ T in seconds.

These are the two relations which you need.

As for calculating the demand and sizing the PV systems you use what is called the load profile which is a graph showing the power of every load and its time duration.

For more information please see the course in the link: Book A course on photo-voltaic array systems

Best wishes