Category Solar Photovoltaic Energy

Open batteries

Voltage measurement of each element and noting of the values in a logbook.

Check appearance: case normal, not distorted, clean terminals (if not clean them), no visible deposit at the bottom of the plates (which indicates a loss of actor material, visible when the case is transparent).

Check the connections: terminal clamps tight, cables in good condition, fuses in place and clean for all batteries.

Electrolyte level: plates well covered (top with distilled water if necessary), no deposit or suspect masses between the grids.

Measure the electrolyte density of each 2 V element: note the values in the same logbook as the voltages and compare the readings; if one or several readings are very different, carry out the measurements again after an equalisation charge and once more after several d...

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System monitoring: checklist

Solar panels

Clean the surface with plain water: remove dirt, sand, any spider’s webs or insects (also in the junction box).

Cut back any vegetation around the panels.

Check the appearance of the modules: no brown cells, no water leakage, no other damage.

Check the stands: check for any corrosion, tighten the mechanical fixings. Note: For a grid-connected system, always disconnect the PV array from the inverter and work with insulated tools and gloves, observing all the safety rules when dealing with high voltages.

Charge controller

Check the fixing of the charge controller and fuses.

Check the state of charge: the indicators should accurately reflect the voltage state of the battery at ‘battery full’, ‘battery charging’ or ‘battery low = load shedding’.

Tighten the terminal ...

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Solar radiation data

image293

Figure A2.1 Solar radiation in Europe. Average values of global solar radiation (expressed over 24 h in December) for orientation due south and a tilt of 60° from the horizontal (in kWh/т2/day)

Country

Place

Lat.

Long.

Jan.

Feb.

Mar.

Apr.

May

Jun.

Jul.

Aug.

Sept.

Oct.

Nov.

Dec.

Norway

Bergen

60.2° N

5.2° E

Gh

196

721

1708

3272

4134

4853

4145

3493

1857

938

302

118

G 60°

S

300

2380

2380

3660

3840

4190

3650

3580

2270

1470

510

170

Germany

Hamburg

53.5° N

10.0° E

Gh

521

2231

2231

3553

4688

5437

4820

4340

2786

1489

671

401

G 60°

S

900

2830

2830

3680

4200

4580

4170

4340

3290

2180

1160

800

Dresden

51...

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Emission by a source of artificial light

Total emission: lumens (lm)

Luminous efficacy of a lamp (quantity of lumens emitted compared to the electric power consumed):

lumens per watt (lm/W)

Illumination received on a surface within the sensitivity of the human eye (400-700 nm):

lux (lx) = lm/m2 (equivalent to W/m2)

Example: Illumination on a desk: 300 lx.

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Intensity of solar radiation

Instantaneous solar radiation received on a surface: watts per square metre (W/m2)

1 W/m2 = 0.1 mW/cm2

Integrated (or cumulative) solar radiation over a period of 24 h (= energy): watts x hour or kilowatts x hour per square metre per day (Wh/m2/day) or (kWh/m2/day)

Appendix 1 343

Example: Average cumulative solar radiation per day in Paris in December:

1.12 kWh/m2/day

Other units of energy: langley (Ly), joule per square centimetre (J/cm2) or kilo­calories per square metre (kcal/m2)

1 J/cm2 = 2.9 kcal/m2 = 2.78 Wh/m2

1 Ly = 1 cal/cm2 = 11.62 Wh/m2

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Light radiation

Wavelength of light radiation

Micrometres (pm) = 10-6 m Nanometres (nm) = 10-9 m

Example: Radiation of colour green: 1 = 550 nm = 0.55 pm

Energy of a photon

hc

E(electron-volt, eV) = hv = —

1

where h is Planck’s constant, v is the frequency, c is the speed of light and 1 is the wavelength, or more simply E = 1.24/1 with E in eV and l in pm.

image291 Подпись: 2.25 eV

Example: Energy of photon with a wavelength of 550 nm:

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Physical sizes and units

Electrical characteristics of an appliance

Instantaneous data

P: electrical power in watts (W) 1 kW = 1000 W = 100,000 mW

I: current consumed in amperes (A) 1 A = 1000 mA = 100,000 pA

V or U: operating voltage in volts (V) 1V = 1000 mV

P = U x I
(W) = (V) x (A)

Example: For appliance consuming 4 A at 12 V, electrical power P = 48 W.

Integrated data over a period of time

E: Energy consumed over a period of time

E = P x N in watt-hours for a period of N hours (Wh) = (W) x (h)

or for a constant system voltage (for example, 12 V)

E = I x N in ampere-hours for a period of N hours

(Ah) = (A) x (h)

Note: This value in Ah is equivalent to the capacity (of a battery, for example). Example: Energy consumed by a 4 A appliance at 12 V for 5 h:

E = 4A x 5 h = 20 Ah at 12 V or E = 48 W x 5 h = 240 Wh

No...

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Wastewater treatment plant in the Vaucluse

A small agricultural commune in the Vaucluse Department of southern France built a wastewater treatment plant below the village far from any electricity lines. They planned to dig a trench to make a connection to the grid, but the owner of the field that had to be crossed refused permission. The plant was finished and only needed a three-phase supply of 3 x 400 V. The commune then decided to supply it using PV panels.

The technical specification was to drive a three-phase pump using 2.2 kW for 3-4 h everyday to transfer the effluent over a height of around 2 m.

Table 5.26 shows all the parameters of this stand-alone system. The first eight lines summarise the system characteristics (voltage, power, current, etc.)...

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