How does the PIDbox help to improve your energy bill?Ilumen
The main reason for efficiency losses of solar panels is Potential Induced Degradation (PID). This phenomenon occurs in all types of solar panels and can be prevented by installing a PIDbox. But how does the PID box installation influence your energy bill?
We will answer this question by means of a realistic numeric example. If you are not familiar with terms such as ‘Peak Power’ and ‘real power’, we recommend you to consult this link before proceeding.
In this numeric example, the payback period of a PIDbox is calculated for a PV system that was installed in Belgium in 2010 and October 2015 respectively.
Consider a PV system of 22 solar panels, each with a Peak Power of 250 Wp. The Peak Power of the global installation therefore equals 5.500 Wp (22 x 250 Wp).
The real power of PV system is 5.225 KWh (0,95 kWh/Wp x 5.500 Wp).
- Electricity price of 0,24 €/kWh
- Increase of yield due to installing PIDbox: 7,45% (average value based on research of ‘Hogeschool Thomas More’)
- Price of PIDbox (installed): 699 €
PV system installed in 2010
The installation of the PIDbox creates a higher return due to electricity savings. These savings are calculated as follows: (7,45% x 5.225 kWh x 0,24 €/kWh) = 93,4 €.
For PV systems installed in 2010 so-called ‘Green Current Certificates’, worth 0,35 euro per kWh of green electricity produced, are granted during 20 years. This results in a return of (7,45% x 5.225 kWh x 0,35 €/kWh) = 136,2 €.
Payback period of the PIDbox in this PV system equals 3,04 years while the return in 20 years is 3.893 € !
PV system installed in October 2010
When installing a PV system today (< 10 kW), Green Current Certificates are no longer granted. Therefore, the return equals the electricity savings. Payback period of the PIDbox therefore increases to 6,42 years while the return in 20 years equals 1.270 euro.
These results should however be interpreted with caution.
- In order to simplify the numeric example, it is assumed that the degradation level due to PID remains constant in time. However it is expected that as the lifetime of the solar panels increases, degradation will occur more strongly (figure 1). This of course results in a shorter PIDbox payback period.
Figure 1: degradation model Koch – PI Berlin
- The increase in efficiency resulting from the installation of the PIDbox in the numeric example equals 7,45%. Research of ‘Hogeschool Thomas More’ however shows efficiency increases up to 17%.
- The numeric example does not take into account potential increase(s) of the electricity price, which would positively affect the investment in a PIDbox.
- Besides, one should also keep in mind that the installation of a PIDbox will contribute to a shorter payback period of solar panels.
- Finally, the installation of the PIDbox will extend the life of solar panels. This obviously has a beneficial effect on your investment.