I recently had a reader, David Lipschitz of My Power Station, ask if I wanted to cover one of his solar installations in South Africa, and at first I thought, "What's the big deal? It's just another solar installation." But then I watched the 8 minute video covering the solar PV installation from beginning to end and I thought it was one of the greatest educational tools to understanding residential solar PV power that I've seen.
I believe that one of the only true ways to understand a subject is to :
A) Read a little about it, but get a hands-on approach to the subject
B) If you can't get a hands-on approach, watch someone do a hands-on approach to the subject. And then watch that many times.
Book learnin' is great, but getting your hand's dirty may be better.
I also like that David listed some of the solar system specs and components used on the Gecko Rock solar PV installation to further help people understand all the items involved:
- 1.6 kilowatt photovoltaic array with 24 Volt 675 Amp Hour battery bank and 1,200 watt inverter charger with generator backup
- 8 kwh of battery backup
- 8 kwh of average daily solar production from the photovoltaic array
- Location: Gecko Rock, 25 km South South East of Touwsriver, Western Cape, South Africa
- Solar Resource: approximately 5 average peak sun-hours
- Photovoltaic Array Size: 1.62 kW (1,620 watts)
- Nominal Voltage Batteries: 24 Volts
- Nominal Voltage Array: 72 Volts
- Array Voltage at Max Power: 108.6 Volts
- Array DC Current at Max Power: 15 Amps
- Battery Amp Hours: 675 Ah (amp hours) at 20-hour discharge rate. Multiplied by 24 Volts and allowing for a 50% maximum depth of discharge = 8.1 kWh in the batteries for overnight and overcast periods
- Record Low Temperature: unknown; we have allowed for Minus 15 degrees Celsius (during day light (operating) hours)
- Average Low Temperature: 2.2 degrees Celsius in July
- Average High Temperature: 28.6 degrees Celsius in February
- Average Daily Production: 8.1 kWh
- Average Electricity Available after taking account of efficiencies (or inefficiencies): Allow 7% for inverter loss; 20% loss for battery charge/discharge from photovoltaic array; and 2% voltage drop on the cabling: 8.1 kwh * 0.93 & 0.8 * 0.98 = 5.9 kwh per day of usable electricity (daily average over the entire year)
PV System Components:
- 9 Tenesol TE1700 at 24 Volt nominal: 180 Wp STC, 36.2 Vmp, 5 Imp, 44.4 Voc, 5.4 Isc (133.2 Volts open circuit for the array (at zero amps, i.e. first thing in the morning) and 16.2 Amps Short Circuit current for the array)
- Array: 1 “string” of 3 “panels” with 3 “modules” in each panel. Total 9 Modules, 1,620 Watts total
- Array installation: Dual-axis (manual) trackers designed by SolarSells, and enhanced, built and installed by Intricate Steel
- Inverters: 1 x 24 Volt Victron 1200 Watt multi-plus Inverter/Charger allowing 24 Volt DC to 220 Volt AC conversion of electricity and allowing automatic synchronisation of a generator input into the system to supplement the batteries in the case of long cloudy periods
- Solar Charge Controllers: 1 x 80 Amp Outback FM80 MPPT (maximum power point tracking) controller. The FM80 allows array sizes up to 2,000 Watts when charging at 24 Volts. The FM80 allows one to use a higher output voltage PV array with a lower voltage battery, such as charging a 24 VDC battery with a 72 VDC array. This reduces wire size (and cost) and power loss from the PV array to the battery/inverter location and maximises the performance of the PV system
- Batteries: Deep Cycle: 12 x 6 Volt Trojan T105′s in 24 Volt nominal configuration, i.e. 3 banks (in parallel) of 4 batteries (in series) making 24 Volts nominal and 675 Amp Hours capacity. Each 6 volt battery weighs 28 kg making a total battery bank weight of 336 kg. We expect the batteries to last about 8 years with an average discharge of 20% and a maximum discharge of 50%. The batteries have a 2 year free replacement guarantee assuming they are looked after and “watered”, i.e. the battery de-ionised water is checked and filled as required. We can tell how the batteries have been used by looking at the information on the Victron Battery Status Monitor. The Trojan batteries are designed in the USA and assembled in Cape Town
- Generator: 5 kw Honda
- System performance metering: Victron Battery Status Monitor BM 600 for DC performance and battery monitoring; Efergy e2 Electricity Monitor for AC performance and historical AC kwh tracking
- 2 Earth spikes and open earthing cabling allowing all metal work to be earthed. System and Equipment negative grounding. We have used USA NEC Article 690 rules as far as possible as there aren’t standards for PV systems in South Africa yet.
What are some other videos you've seen on explaining renewable energy, energy conservation, and sustainability?