Dear Paul,
Hello again. Sorry for my long messages but i try to describe problems in detail so we can all benefit from it.
I have another problem regarding the annual energy & system output to grid reported in the metrics table and loss diagram correspondingly.
I have simulated a 50MW power tower with 50MW fossil fuel backup. My fossil fill fraction is set to 1.05 same as tub.out. fraction and max. turbine over design op. Storage dispatch is set to 0 for both w/o solar and w/solar.
The problem in results is that SAM reports the SYSTEM OUTPUT TO GRID 887,322 MWhe while in the metric table the ANNUAL ENERGY is 374,003,360 kWhe.
I have found a post in these forums that you have replied saying that the annual energy must be equal to the system output to grid and that's perfectly understandable. So i removed the fossil fill fraction from my simulation and both reported values were the same as expected. By the way at this point the reported annual energy was not the same (less) as the one with fossil fuel backup in my previous simualation so i presume that fossil fuel backup contribution is added in the annual energy for systems that utilise it.
Now why when i put the fossil fuel backup to 1.05 for all my periods (2 totally) i get much much higher energy output in the loss diagram? I took the time series hourly values for net electric output and compared them withthe values below:
Net electric power output (kWh), hourly is 389,586,850.15 kWhe
Thermal energy delivered by aux backup, hourly is 496,491,531.37 kWht. If i make a rough calculation of the thermal energy to electric conversion by using my rated cycle conversion efficiency (0.42) i get 208,526,443.18 kWe from the aux. backup and this is not even calculated with my 96% annual performance adjustment.
Thermal energy from thermal storage is 119,844,280.000 kWh(positive values calculated with 0.42 conversion efficiency).
Now if you add the numbers of Net electric + Electric from aux. backup 6 thermal energy from storage i will still be missing 169,364,426.67 kWhe.
Also in the time series i get 44,473.00 KWhe hourly net electric output approx. which is my target for guarantee provided energy. However according the loss diagram the electricity provided to the grid is much higher which results to 101,000 KWhe hourly. approx.(not reported in the time series).
I have attached a .PDF file with 2 photos of my loss diagram and metric table.
What am i missing here? :(
What is the annual energy value reporting exactly? Does it include the electricity generated by the power cycle from the provided thermal energy of fossil fuel?
I am using SAM 2013.1.15 (windows XP).
Thank you in advance.