**5.1.3 Daily load requirement**

An assumption of a lighting programme in poultry house where power is needed for four out of every seven days in a week was made, and the inverse relationship between voltage and amperage was used to determine the average daily current requirement by multiplying current by a factor of 4/7 to yield a net value in Ah, the average daily current required to satisfy the load demand of 5.14Ah as calculated from given relations. An average of 4½ hrs of full sunshine hours per day round the years is taken for a non-critical system. The thermocouple array load capable of generating the required load demand is obtained by dividing the average daily current requirement by 4.5.

```
Thermocouple load = average daily current requirement /4.5 (A).
```
When a peak sunshine hour of 4.5 hours/day is required, the thermocouple array designed is capable of generating a measured 1.14A, capable of providing a glow continuously to satisfy the load demand of 5.14Ah. At increased number of sunshine hours above 4 ½ hours, more current generation is possible whereby the battery could be recharged.

### **5.1.4 The system conversion efficiency**

The conversion efficiency is defined as the ratio of electrical power output and the heat flux through the entire TEG surface.

$$
\varepsilon = \frac{p}{Q} = \frac{p}{\Delta T \, A \, h} \tag{38}
$$

Δ*T* corresponds to the temperature difference between the hot and the cold side of the TEG, *A* is the TEG area and *h* is the overall heat transfer coefficient given by (the ratio of total thermal conductivity (5.4 x 10 -4 W/m2/°C) of the materials of the thermoelectric generators and the thickness (0.015m) of the TEG. The electrical power output (P=174.06 W h). The measured heat flux through the entire TEG surface is 10.94 W. The overall conversion efficiency of the system calculated is 15.91%. The cost of system production is estimated at average N20, 000.00
