20.1
20
PV system design
In Chapter 15, we thoroughly discussed PV modules. Further, in Chapter 18 we discussed
how to estimate the irradiance on a PV module in dependence of the position of the Sun
and partial absorption and diffusion in the atmosphere. Finally, we introduced all the other
components of PV Systems in Chapter 19.
In this chapter, we will combine the knowledge gained so far in order to design
complete PV systems. We can design PV systems at different levels of complexity. For a
first approximation, the performances of the PV modules and the other components (like
the inverter) at standard test conditions (STC) and the number of equivalent sun hours
(ESH) at the location of the PV system are sufficient. The concept of STC (AM1.5
illumination with a total irradiance of 1,000 W/m
2 and a module temperature of 25 °C)
was already introduced in Chapter 9; the notion of ESH will be discussed below. In a more
detailed approach, performance changes of the different components due to changing
irradiance and weather conditions are taken into account. Since these performance
changes can be quite high, they can alter the optimal system design considerably.
There are two main paradigms for designing PV systems. First, the system can be
designed such that the generated energy and the loads, i.e. the consumed energy, match.
Hence, an energy balance must be done Secondly, the design of a PV system can be based
on economics. We must distinguish between grid-connected and stand-alone systems. As
we will see, the two have very different demands.
This chapter is organised as follows: First, as an example, we will discuss a design of
a simple stand-alone system in Section 20.1. After that we will take a more detailed look
at load profiles in Section 20.2. In Section 20.3 we discuss how weather and irradiance
conditions affect the performance of PV modules and BOS components, mainly inverters.
Finally, in Sections 20.4 and 20.5 we learn how to design grid-connected and stand-alone
systems, respectively.
A simple approach for designing stand-alone
systems
20
PV system design
In Chapter 15, we thoroughly discussed PV modules. Further, in Chapter 18 we discussed
how to estimate the irradiance on a PV module in dependence of the position of the Sun
and partial absorption and diffusion in the atmosphere. Finally, we introduced all the other
components of PV Systems in Chapter 19.
In this chapter, we will combine the knowledge gained so far in order to design
complete PV systems. We can design PV systems at different levels of complexity. For a
first approximation, the performances of the PV modules and the other components (like
the inverter) at standard test conditions (STC) and the number of equivalent sun hours
(ESH) at the location of the PV system are sufficient. The concept of STC (AM1.5
illumination with a total irradiance of 1,000 W/m
2 and a module temperature of 25 °C)
was already introduced in Chapter 9; the notion of ESH will be discussed below. In a more
detailed approach, performance changes of the different components due to changing
irradiance and weather conditions are taken into account. Since these performance
changes can be quite high, they can alter the optimal system design considerably.
There are two main paradigms for designing PV systems. First, the system can be
designed such that the generated energy and the loads, i.e. the consumed energy, match.
Hence, an energy balance must be done Secondly, the design of a PV system can be based
on economics. We must distinguish between grid-connected and stand-alone systems. As
we will see, the two have very different demands.
This chapter is organised as follows: First, as an example, we will discuss a design of
a simple stand-alone system in Section 20.1. After that we will take a more detailed look
at load profiles in Section 20.2. In Section 20.3 we discuss how weather and irradiance
conditions affect the performance of PV modules and BOS components, mainly inverters.
Finally, in Sections 20.4 and 20.5 we learn how to design grid-connected and stand-alone
systems, respectively.
A simple approach for designing stand-alone
systems