Instruction Manual

PowerOptimal Elon® 100 Installation Manual
Version date: 2022/05/23
Page 30 of 37
Version number: 2.20
© PowerOptimal (Pty) Ltd 2022. The content of this document is confidential and all rights to the intellectual
property and/or information contained herein remain vested in PowerOptimal, except if otherwise agreed in
writing.
Appendix F. Surge Protection Device (SPD) Recommendations
This Appendix outlines under which circumstances a Surge Protection Device should be installed as
part of a solar PV system installation such as the Elon® 100.
The draft standard "SANS 10142-3: Proposed Interim Guideline for the wiring of LV grid-embedded PV
installations not exceeding 1000kVA in South Africa" requires a Surge Protection Device to be installed
where the length (L) of the DC cables (from PV array to Elon® 100 or inverter) exceeds the critical
length Lcrit as follows:
A Surge Protection Device is required where L ≥ Lcrit
The critical length Lcrit depends on the type of PV installation and is calculated according to the
following table:
Type of installation
Individual residential
premises
Terrestrial production
plant
Service / Industrial /
Agricultural Buildings
Lcrit (in meter)
115/Ng
200/Ng
450/Ng
where Ng = lightning strike density (number of strikes/km²/yr)
The length of DC cables L is the sum of:
• distances between the inverter(s) and the junction box(es), while observing that the lengths
of cable located in the same conduit are counted only once, and
• distances between the junction box and the connection points of the photovoltaic modules
forming the string, observing that the lengths of cable located in the same conduit are counted
only once.
For the Elon® 100, distance L is the length of DC cables from PV array to the Elon® 100.
On the next page is a national lightning ground stroke density map for South Africa
5
.
From this map, the lightning strike density (Ng) range for major cities are as follows:
City
Lightning strike
density Ng
(strikes/km²/yr)
Lcrit (m)
Individual residential
premises
Service / industrial /
agricultural buildings
Cape Town
0.02 to 4
29
113
Stellenbosch
0.02 to 4
29
113
Worcester
0.02 to 4
29
113
George
0.02 to 4
29
113
Saldanha
0.02 to 4
29
113
Port Elizabeth
0.02 to 4
29
113
East London
4 to 6
19
75
King Williams Town
4 to 6
19
75
Beaufort-West
4 to 6
19
75
Musina
4 to 6
19
75
Britstown
6 to 15
8
30
Durban
6 to 15
8
30
5
Evert CR, Gijben M. 2017. Official South African Lightning Ground Flash Density Map 2006 to 2017.