PowerOptimal Elon® 100 specification V2.20

INTRODUCING THE

PowerOptimal Elon® 100

The innovative PowerOptimal Elon® 100 incorporates proprietary solar PV (photovoltaic) power management technology to allow for direct connection of solar PV arrays to electric geysers (water heaters) with optimised solar power use in a single compact unit. The system can be connected to the grid (AC mains) as well, and intelligently switches between AC and solar power supply. The system requires no inverter and no battery. It can be connected to standard AC geyser heating elements and AC thermostats, which translates into the most cost-effective solar water heating option today.

Document Version: 2.20

SPECIFICATIONS

Rated input voltage

250V AC, 250V DC

Rated input current

25A AC, 20A DC

Mains (AC) voltage range (over-voltage & undervoltage protection)

-50% to +100%. Overvoltage protection up to 500V and undervoltage protection down to 125V. Will disconnect all loads when breach is greater than +/- 15%.

System power supply

Solar or 230V AC mains

Power consumption

<3W on mains power; <0.5W on solar power

Shutdown

Sufficient power supply capacity to manage processor, switching and data storage if both mains and solar supply fail

Solar voltage (V_oc at STC)

20 – 250 V DC

Solar power availability sensing

Automatically determines availability of sufficient solar power before supplying load from solar PV array

Controller settings

Can be adjusted to run from “solar only” (100% solar energy use) to “mains only” (no solar energy use) with 3 settings in between to allocate different proportions of the day to solar and mains.

Thermostat

Uses the standard thermostat switch associated with the geyser element as a sensor only, with less than 10mA sense current, to control power to the element

Reverse polarity protection

Protected against reverse connection of solar array

Enclosure ingress protection rating

Elon 100 main unit: IP65

Elon 100 remote control: IP40 (install indoors or in waterproof enclosure)

Max. distance Elon® unit to controller

10 m (can be extended)

Annual energy production compared to inverter-based system

> 90% when solar array and geyser element are matched correctly

Standards conformance

IEC / SANS 60669-1, 60669-2-1, 60730-1, 60335-1, 60335-2-21, CISPR 11 & IEC 61000-6-1

Dimensions & weight

Elon® 100 main unit: 200 x 150 x 90 mm (LxWxH), 1.75 kg. Controller: 50 x 72 x 41 mm (LxWxH)

Box information (for shipping): 230 x 150 x 150 mm (LxWxH), 2 kg.

Patents

ZA 2019/02129

It is important to match the solar PV array and heating elements for maximum power transfer efficiency. See Table 1B for the recommended AC heating element power rating for different solar panel specifications and configurations.

Contact PowerOptimal for advice on module-element matching if module properties are significantly different to typical values or for bifacial, high current or high voltage modules.

TABLE 1A. ELON® KIT EASY SELECTION GUIDE – HOW MANY SOLAR PV MODULES DO I NEED?

The below table provides an easy selection guide based on number of people in the household and/or hot water use (showers/day). Minimum recommended array size is 1 kW_p. More detailed information and selection guidelines are provided in Tables 2-7.

~~Solar~~ ~~PV array size~~ ~~(kW~~_p)	Showers per day*	~~50%+ of daily hot water use provided for how many people?~~	~~How many people off-grid for hot water?~~	~~Typical number of solar PV modules~~
~~1 – 1.2~~				~~2 - 3 modules~~
~~1.2 – 1.6~~				~~3 - 4 modules~~
~~1.5 – 2~~				~~4 - 5 modules~~
~~2.4 – 3.2~~ ~~(two parallel PV strings)~~				~~6 - 8 modules~~
~~3 – 4~~ ~~(two parallel PV strings)~~				~~8 - 10 modules~~

* 6-minute showers at 40 °C with 8 litre/min (low-flow) showerheads

TABLE 1B. ELON® KIT EASY SELECTION GUIDE – WHAT SIZE GEYSER ELEMENT IS THE BEST MATCH?

To get the best performance from your Elon® solar PV water heater, it is important that the geyser element is a good match for the size of your solar PV array. This table helps you match the size of the solar PV array with the size of the geyser element.

~~Solar~~ ~~PV array size~~ ~~(kW~~_p)	~~Best matching geyser element size~~ ~~(kW)~~	2^nd choice geyser element size* ~~(kW)~~	~~Geyser (water tank) size~~ ~~(litres)~~
~~1 – 1.6~~	4	3	~~100 - 200~~
~~1.6 – 2~~	3	~~4 or 2~~	~~100 - 200~~
~~2 - 3~~	3	4	~~150 – 300~~
~~2 – 4~~ ~~(two parallel PV strings)~~	4	NA	~~200+~~

* Second-choice element size would reduce efficiency by 10 – 20%.

~~Maximum~~ ~~allowed~~ ~~solar PV array specifications at Standard Test Conditions (~~~~STC~~):

I_sc ~~< 20A V~~_oc ~~< 250V Power < 4 kW~~_p

TABLE 2. 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

119

139

159

179

199

249

298

348

Cape Town

1624

102

119

136

154

171

213

256

299

Durban

1447

106

122

137

152

190

228

266

Jhb/Pretoria

1724

109

127

145

163

181

226

272

317

Mbombela

1627

103

120

137

154

171

214

256

299

Port Elizabeth

1565

115

132

148

164

205

247

288

Upington

1912

100

121

141

161

181

201

251

301

352

Saldanha

1623

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.

TABLE 3. ANNUAL AVERAGE NUMBER OF SHOWERS PER DAY

The below table indicates the average number of showers per day for which the system will supply hot water 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®

Number of showers per day (based on annual average) 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

2.4

3.0

3.6

4.2

4.8

5.4

6.0

7.5

9.0

10.4

Cape Town

1624

2.0

2.6

3.1

3.6

4.1

4.6

5.1

6.4

7.7

9.0

Durban

1447

1.8

2.3

2.7

3.2

3.6

4.1

4.6

5.7

6.8

8.0

Jhb/Pretoria

1724

2.2

2.7

3.3

3.8

4.3

4.9

5.4

6.8

8.2

9.5

Mbombela

1627

2.1

2.6

3.1

3.6

4.1

4.6

5.1

6.4

7.7

9.0

Port Elizabeth

1565

2.0

2.5

3.0

3.5

3.9

4.4

4.9

6.2

7.4

8.6

Upington

1912

2.4

3.0

3.6

4.2

4.8

5.4

6.0

7.5

9.0

10.5

Saldanha

1623

2.0

2.6

3.1

3.6

4.1

4.6

5.1

6.4

7.7

9.0

The table is based on 6-minute showers at 40 °C and 8 litres/min low flow showerheads. Old showerheads can use up to 15 litres/min and would substantially reduce the number of showers.

Example:

For a solar PV array of 2.5 kW_p, an installation in Johannesburg would yield about 1724 kWh/kW_p/yr, or 1724 x 2.5 kW_p = 4 310 kWh/yr. This would be sufficient for about 6 to 7 showers per day.

TABLE 4. PERCENTAGE OF ANNUAL HOT WATER REQUIREMENT

The below example table indicates what % of the annual hot water requirement will on average be supplied by the system for 2 people each using 80 litres of hot (60 °C) water per day. (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 % of hot water requirement supplied for 2 people each using 80 litres of hot water 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

50%

62%

75%

87%

99%

112%

124%

155%

187%

218%

Cape Town

1624

43%

53%

64%

75%

85%

96%

107%

133%

160%

187%

Durban

1447

38%

47%

57%

66%

76%

85%

95%

119%

142%

166%

Jhb/Pretoria

1724

45%

57%

68%

79%

91%

102%

113%

142%

170%

198%

Nelspruit

1627

43%

53%

64%

75%

85%

96%

107%

134%

160%

187%

Port Elizabeth

1565

41%

51%

62%

72%

82%

92%

103%

128%

154%

180%

Upington

1912

50%

63%

75%

88%

100%

113%

126%

157%

188%

220%

Saldanha

1623

43%

53%

64%

75%

85%

96%

107%

133%

160%

186%

Examples:

An array of 1.2 kW_p will provide approximately 64% of the annual hot water requirement for a family of two people in Cape Town.

An array of 2 kW_p will provide approximately 124% x (2 / 4) = 62% of the annual hot water requirement for a family of four people in Bloemfontein.

TABLE 5. PEAK POWER OUTPUT FOR VARIOUS SOLAR MODULES AND ARRAY SIZES

The peak power production (W_p) of the modules at STC (Standard Test Conditions: irradiance 1000 W/m², spectrum AM 1.5, module temperature 25 °C) and at NOCT (Nominal Operating Cell Temperature, irradiance 800 W/m², spectrum AM 1.5, module temperature ~43 – 45 °C) are provided by the solar PV module manufacturer. The below table indicates the peak power at STC for a range of solar module power ratings and array sizes.

No. of cells per module

Module STC power rating (W_p)

Total peak power at STC in kW_p for an array of X modules

modules

4 modules

5 modules

6 modules

8 (2 x 4) modules

10 (2 x 5) modules

12 (2 x 6) modules

60 or 120

265

0.795

1.06

1.325

1.59

2.12

2.65

3.18

60 or 120

270

0.81

1.08

1.35

1.62

2.16

2.70

3.24

60 or 120

275

0.825

1.10

1.375

1.65

2.20

2.75

3.30

60 or 120

280

0.84

1.12

1.40

1.68

2.24

2.80

3.36

60 or 120

285

0.855

1.14

1.425

1.71

2.28

2.85

3.42

60 or 120

290

0.87

1.16

1.45

1.74

2.32

2.90

3.48

60 or 120

295

0.885

1.18

1.475

1.77

2.36

2.95

3.54

60 or 120

300

0.90

1.20

1.50

1.80

2.40

3.00

3.60

60 or 120

305

0.915

1.22

1.525

1.83

2.44

3.05

3.66

60 or 120

310

0.93

1.24

1.55

1.86

2.48

3.1

3.72

60 or 120

315

0.945

1.26

1.575

1.89

2.52

3.15

3.78

60 or 120

320

0.96

1.28

1.6

1.92

2.56

3.2

3.84

60 or 120

325

0.975

1.3

1.625

1.95

2.6

3.25

3.9

60 or 120

330

0.99

1.32

1.65

1.98

2.64

3.3

3.96

72 or 144

310

0.93

1.24

1.55

1.86

2.48

3.10

3.72

72 or 144

315

0.945

1.26

1.575

1.89

2.52

3.15

3.78

72 or 144

320

0.96

1.28

1.60

1.92

2.56

3.20

3.84

NOT ALLOWED

(exceeds maximum rated Elon® 100 voltage)

72 or 144

325

0.975

1.30

1.625

1.95

2.60

3.25

3.90

72 or 144

330

0.99

1.32

1.65

1.98

2.64

3.30

3.96

72 or 144

335

1.005

1.34

1.675

2.01

2.68

3.35

4.02

72 or 144

340

1.02

1.36

1.70

NOT ALLOWED

(exceeds maximum rated Elon® 100 voltage)

2.04

2.72

3.40

4.08

72 or 144

345

1.035

1.38

1.725

2.07

2.76

3.45

4.14

72 or 144

350

1.05

1.40

1.75

2.10

2.80

3.50

4.20

72 or 144

355

1.065

1.42

1.775

2.13

2.84

3.55

4.26

72 or 144

360

1.08

1.44

1.8

2.16

2.88

3.6

4.32

72 or 144

365

1.095

1.46

1.825

2.19

2.92

3.65

4.38

72 or 144

370

1.11

1.48

1.85

2.22

2.96

3.7

4.44

72 or 144

375

1.125

1.5

1.875

2.25

3.75

4.5

72 or 144

380

1.14

1.52

1.9

2.28

3.04

3.8

4.56

72 or 144

385

1.155

1.54

1.925

2.31

3.08

3.85

4.62

72 or 144

390

1.17

1.56

1.95

2.34

3.12

3.9

4.68

72 or 144

395

1.185

1.58

1.975

2.37

3.16

3.95

4.74

72 or 144

400

1.2

1.6

2.4

3.2

4.8

72 or 144

405

1.215

1.62

2.025

2.43

3.24

4.05

4.86

72 or 144

410

1.23

1.64

2.05

2.46

3.28

4.1

4.92

72 or 144

415

1.245

1.66

2.075

2.49

NOT ALLOWED

(exceeds maximum rated Elon® 100 voltage)

3.32

4.15

4.98

72 or 144

420

1.26

1.68

2.1

2.52

3.36

4.2

5.04

NOT ALLOWED

(exceeds maximum rated Elon® 100 voltage)

72 or 144

425

1.275

1.7

2.125

2.55

3.4

4.25

5.1

72 or 144

430

1.29

1.72

2.15

2.58

3.44

4.3

NOT ALLOWED

(exceeds maximum Elon® 100 power rating)

5.16

72 or 144

435

1.305

1.74

2.175

2.61

3.48

4.35

5.22

72 or 144

440

1.32

1.76

2.2

2.64

3.52

4.4

5.28

72 or 144

445

1.335

1.78

2.225

2.67

3.56

4.45

5.34

72 or 144

450

1.35

1.8

2.25

2.7

3.6

4.5

5.4

72 or 144

455

1.365

1.82

2.275

2.73

3.64

4.55

5.46

Examples:

An array of 4 x 325 W_p modules in series will have a total peak power (at STC) of 1.3 kW_p.

An array of 2 parallel strings of 5 modules of 280 W_p each (10 modules of 280 W_p in total) will have a total peak power (at STC) of 2.8 kW_p.