The maximum efficiency ratio (η/〖Opt〗_η =1) occurs when the load resistance ratio (mratio) equals about 1.2 for TG modules. This is highlighted by point one on the off peak performance curve shown here and is the point at which the maximum efficiency curves are given. When the maximum efficiency curves are used in conjunction with the normalized off peak performance curve, the non-load matched, or non-maximum efficiency values, can be determined. To determine the efficiency and TG voltage, the actual load resistance ratio must be determined. Determine the operating load resistance ratio expected for the application by dividing the actual electrical load impedance by the TEG impedance. Draw a vertical line from the appropriate load ratio on the x-axis up to the Efficiency curve. The example assumes a load ratio = 5. To determine the power output, draw a horizontal line from the intersection of the efficiency curve and vertical line in step 2 to the η/〖Opt〗_η axis. This value represents the percentage of the optimal efficiency and optimal power that will be achieved for the given load condition. Use this value to scale power output from the optimal performance graph. To determine the voltage output of the TG in non-optimal conditions, draw a horizontal line from the intersection of the voltage curve to the voltage/VOC axis. Multiply this value by the open circuit voltage given in the datasheet performance table to calculate the TEG voltage under the given load. Similarly, note that the optimal Voltage/VOC is obtained by drawing a horizontal line from the voltage curve at the maximum efficiency point (point 1).