Changing Temperatures of Multiple Solar Cells

I'm Simulating a PV panel and need to obtain readings from the panel at different temperatures. I've used solar cells and grouped them into subsystems. To change the temperature of the solar cell i use the following code:

   blocks = find_system('PV_panel','BlockType','Solar Cell');
   n = length(blocks);

    for i = 1:1:n
        set_param(blocks{i,1},'TFIXED','T');
    end

With this code the i get an empty array for 'blocks'. If i use:

blocks = find_system('PV_panel','BlockType','SubSystem')
I get all the blocks in the sub system. 
EG:
'PV_panel/Current Sensor'
'PV_panel/Electrical Reference'
'PV_panel/G'
'PV_panel/PS-Simulink Converter'
'PV_panel/PS-Simulink Converter1'
'PV_panel/PV'
'PV_panel/PV/Panel1'
'PV_panel/PV/Panel1/Solar Cell'
'PV_panel/PV/Panel1/Solar Cell1'
'PV_panel/PV/Panel1/Solar Cell2'
etc.

How do i obtain the path of only the solar cells to change it's temperature. Or is there any other way to change the temperature of Solar Cells?