Get status returns different efficiency values depending on h parameter


#1

I’ve noticed a difference in the efficiency value returned from getstatus depending on the value of the history parameter.

With h=0:

POST to /service/r2/getstatus.jsp: {'h': 0, 't': '12:00', 'ext': 0, 'd': '20170819', 'limit': 1, 'asc': 1}
HTTP response: 200 (OK): 20170819,12:00,11283,2141,NaN,NaN,0.240,27.0,408.6

With h=1:

POST to /service/r2/getstatus.jsp: {'d': '20170819', 't': '12:00', 'asc': 1, 'ext': 0, 'h': 1, 'limit': 1}
HTTP response: 200 (OK): 20170819,12:00,11283,1.266,2141,5496,0.617,NaN,NaN,27.0,408.6

For h=0 it seems like efficiency is calculated as power generation / system size, while for h=1 it seems to be energy generation / system size. Is this as expected?

System id above is 46706.


#2

For h=1 the average power is used in the efficiency calculation.

For h=0 the instantaneous power is used.


#3

For h=0, shouldn’t the unit in the documentation be kW/kW and not kWh/kW then?

For h=1, isn’t the average power used to calculate “Normalised output”? In the example above system_size * normalised_output = 8.91 * 0.617 = 5.49 = average_power.

Also, system_size * efficiency = 8.91 * 1.266 = 11.28 = energy_generation. This also seems to be how efficiency is calculated in the live view in the web interface.


#4

You are right, the documentation has been updated to ‘Normalised Output’ kW/Kw for h=0


#5

Why is it that h=0 uses instantaneous power while h=1 uses the average power? From reading the documentation I would expect “Normalised output” to be the same independent of the value of h.


#6

h=0 returns the latest status, it is a single data point so instantaneous power must be used.

If you want consistency, always use h=1


#7

Ok. Perhaps mention this in the docs?

Thanks for the help!