User Guide

www.poweroptimal.com Document Version: 2.08
[e-mail] Page: 3 of 10
Directors: RA Fearon, FS Moolman, JJ Theron, DM Weber (Non-Executive), IR Jandrell (Independent)
Company registration number: 2012/099947/07
PO Box 5, Kleinmond, 7195
SECTION B. SOLAR PV ARRAY AND HEATING ELEMENT FULL SELECTION GUIDE
It is important to match the solar PV array and heating elements for maximum power transfer efficiency.
HOW TO USE THIS GUIDE:
1. Use Tables 1 to 4 to help you select the right size solar PV array for your needs.
2. Then use Table 5 to find the recommended AC heating element power rating for your selected solar PV array.
3. Use Table 6 to check element & thermostat compatibility with the Elon® 100.
Contact PowerOptimal for advice on module-element matching if module properties (maximum power point current and
voltage) are significantly different to typical module properties, or for advice on bifacial & high voltage modules.
TABLE 1. ANNUAL AVERAGE LITRES OF WATER HEATED PER DAY
The below example table indicates the average number of litres of water per day that the system will heat from 15 to 60 °C
over a year period for different solar array peak power ratings. (The amount of water heated will vary with weather
conditions, by geographic location and by season. Water heated per day will be significantly lower in winter and
significantly higher in summer. These numbers indicate heating capacity – i.e. if no hot water is used on a given day, there
will be less water heated on that day. This is only an approximate guide.)
Solar + Elon®
Annual average litres of water heated per day for X kW
p
installed solar capacity
Location
kWh/kW
p
/yr
0.8 kW
p
1 kW
p
1.2 kW
p
1.4 kW
p
1.6 kW
p
1.8 kW
p
2 kW
p
2.5 kW
p
3 kW
p
3.5 kW
p
Bloemfontein
1894
80
99
119
139
159
179
199
249
298
348
Cape Town
1624
68
85
102
119
136
154
171
213
256
299
Durban
1447
61
76
91
106
122
137
152
190
228
266
Jhb/Pretoria
1724
72
91
109
127
145
163
181
226
272
317
Mbombela
1627
68
85
103
120
137
154
171
214
256
299
Port Elizabeth
1565
66
82
99
115
132
148
164
205
247
288
Upington
1912
80
100
121
141
161
181
201
251
301
352
Saldanha
1623
68
85
102
119
136
153
170
213
256
298
Example:
For a solar PV array of 1.2 kW
p
, an installation in Johannesburg would yield about 1724 kWh/kW
p
/yr, or 1724 x 1.2 kW
p
=
2069 kWh/yr. This would be sufficient to heat on average 109 litres of water per day. For a family of 2 each using 80 litres
of hot water per day, this would provide about 109 ÷ (80 x 2) or 68% of the annual hot water requirement.