**3.1 Deriving customer's requirements**

**Reference Description Formula Comments**

*Quality Control - Intelligent Manufacturing, Robust Design and Charts*

*j*¼1 *F jk <sup>j</sup>*

*=d* Where;

*<sup>C</sup>* <sup>¼</sup> *<sup>M</sup>*<sup>2</sup> <sup>þ</sup> *<sup>I</sup>* 2

Where;

Kj = weight of level j; 1,2,

di = demand of part variant d = total demand of product

M = Module/components I = interactions

Not selected because only a few of the publications reviewed in this study disclosed the functional analysis of their

This approach is based on the availability of product components in the market. Therefore, this method is not relevant for

Since most publications describe their devices in terms of assemblies, components, and their interactions, this method was found to be the most suitable

designs.

use in this study.

for this research.

Where; C = complexity L = number levels Fj = number of functions at

level j

functions *<sup>C</sup>* <sup>¼</sup> <sup>P</sup>*<sup>l</sup>*

[9] Number of

[11] Number of

*Design complexity metric system.*

**Table 2.**

**Figure 2.**

**96**

*Design approach for developing a solar tracker.*

[10] Demand *C* ¼ *di*

components and interaction

The requirements of a dual axis tracker were established from an interview conducted with a facility technician at the Phakalane solar plant (Botswana). This was to understand the requirements of a dual axis solar tracker from an expert. The following questions divided into two categories, namely, functional and nonfunctional aspects were asked in the direct interview:

**Functional aspects**: The following six (06) questions were asked under functional aspects.

1.What defines the best performing solar tracking, in terms of its;


**Non-functional aspects**: the following four (04) questions were asked under this non-functional aspect.

1.What method of waste disposal will be used after product life cycle?

2. Is the 3Rs (reuse, reduce and recycle) approach embedded in the product?

3.How will the operation of the device affect wildlife, birdlife and water sources?

4.What level of aesthetics is required for the system?

The requirements described in **Table 3** were identified during the interview.

#### **3.2 Setting design objectives**

Firstly, the Universal Track Racks™ by ZomeWorks (in **Figure 3**) was used to come up with the basic functions of a solar tracking system due to its popularity. The tracking system uses two or four *(if is dual axis)* identical cylinders on the edges of a panel frame. These contain a working thermo-fluid (normally a refrigerant). As the position of the sun changes with time, one cylinder receives more thermal power than the other. Due to this, the refrigerant expands and flows to another cylinder through a duct. From this process the function identified is the ability to detect the new position of the sun at a reference point. As the fluid accumulates in the other cylinder, there is difference in weight of the two cylinders. Since system is


a. To precisely determine the position of the sun.

*Form follows functions* approach was used at this stage. That is, functions establishment should be independent of geometrical state to broaden the solution space [4]. A function is a task that transforms input to output in the system [13]. Therefore, functional modelling is a framework that relates functions in a flow, processes,

*Improving Product Quality through Functional Analysis Approach: Case of Dual Axis Solar…*

**identified**

PV system coupled to the support structure

• Wind load • Rain load • Measure of wind • Measure of rain • Measure of cloud shade

• Mechanical Energy • Electrical Energy

**Type of input (energy, material or signal)**

Sun position Signal • Sun

PV system Material • Electrical

User Signal User

• Energy (Wind and rain loads) • Signal (Measure of rain, wind and cloud shade)

Energy Waste

Material • PV

Solar energy Energy

**Output**

position • Signal for control

energy • PV • Solar energy

> system + Support structure

• Wind load • Rain load • wind • rain • cloud shade

energy (heat and noise)

**Description Inputs**

There is change in position the sun (triggers the need to measure the change in sun position).

To increase output of PV by tracking (PV generates electrical energy from sunlight directly)

There is a need for support structure to provide facilitate motion and solid orientation (the support structure is coupled

The level of interaction with human is low. That is the user only monitors the machine at time of maintenance and unforeseen

The environmental conditions such as wind, rain and cloud shade

This is based on choice of input energy and mechanism (there selection of mechanical energy for providing torque with recycling of waste energy and electrical energy used for power calibration devices

will affect the tracker

can minimise energy)

*Thought aid process applied for becoming the flow.*

to the PV)

operations

b. To calibrate the positioning mechanism.

c. To generate the tracking motion.

*DOI: http://dx.doi.org/10.5772/intechopen.93951*

d. To monitor tracking effect.

**3.3 Functional analysis**

**Retrieval questions**

Why is there a need to track the sun for PV application?

Can PV system rotate on itself?

How is automation of the system going to be achieved?

Is the system environmental conditions proof?

How is the energy going to be minimised?

**Table 4.**

**99**

and the operations to a system.

#### **Table 3.**

*Identified design requirement for dual axis solar tracker.*

designed to detect imbalance through a centre pivot, then motion is generated by this effect. To avoid shock on the system, a damper is used to guide and regulate; as other components rotate towards the desired position [12]. From this process four main sub-functions can be summarised as follows;

*Improving Product Quality through Functional Analysis Approach: Case of Dual Axis Solar… DOI: http://dx.doi.org/10.5772/intechopen.93951*

