２． Solar Home Systems (SHS) Herb Wade PPA Consultant

1. ２．Solar Home Systems (SHS)Herb WadePPA Consultant Solar PV Design Implementation O& M March 31- April 11, 2008 Marshall Islands

2. 2. Solar Home Systems(SHS) • Contents 2-1. Basic principles of SHS 2-2. Solar Home Systems(SHS) 2-3. System configuration 2-4. Solar Panels 2-5. Controllers 2-6. Batteries for Solar Home Systems 2-7. What about battery additives that are supposed to ‘rejuvenate’ old batteries. Do they work? 2-8. Appliances 2-9. Wiring 2-10. Installation of SHS 2-11. Preventive Maintenance 2-12. Troubleshooting

3. 2-1. Basic Principles of SHS

4. Solar Photovoltaics for Rural Home Electrification

5. A Little History • Solar Photovoltaics (PV) was first practically demonstrated in the 1950s though laboratory development occurred in the 19th century • The cost of solar power has continually decreased since then though it is leveling off now.

6. More history • Initially solar PV was used in the 1960s mainly for powering space vehicles since it was too expensive for general use • By the 1970s the cost had fallen enough to allow PV to start to be used for remote power for telecommunications and pumping • By the 1980s, the cost had fallen to the point where home electrification in remote areas was practical • By 2000, hundreds of thousands of homes worldwide used solar panels for lighting and radio power and the technology was considered mature with solar cheaper than village diesel grids. • Today, fuel prices have risen to the point where solar now produces electricity at a cost comparable with medium sized diesel generators, about US$0.30/kWh

7. Advantages of Solar Home Systems (SHS) when compared with village diesel systems • Fast to install. No grid or power house required. • No noise • 24 Hour Power • Cheaper than grid extensions or diesel generators for low load customers • No environmental damage from operation • Adequate power for low income rural households • Individual power systems are installed for each house, so power is not lost by the whole village if something fails • Modular construction so electrification can quickly and easily be extended to more houses in a village

8. Disadvantages of householdsolar PV • Limited energy availability, not suitable for industry or powering high demand appliances • Energy availability is related to the weather • Cost increases in step with energy delivered, there is little economy of scale • Solar power is DC while common appliances require AC • Requires decentralized maintenance and administration

9. Common uses of solar power • Remote telecommunications stations • Home lighting and small entertainment appliance power • Battery charging • Small to medium scale water pumping • Public building electrification in remote areas • Street lighting in remote areas • Stand alone portable or fixed power supply for low demand loads (watches, calculators, warning lights, sign lighting, boats, etc.)

10. Solar Mini-Grid • The same grid structure as a diesel mini-grid, only the generation is solar. • Like a very large SHS with an inverter. Same basic components but larger

11. Rural Electrification Comparison

12. 2-2. Solar Home Systems (SHS)

13. Basic system

14. Tasks that are performed by a SHS • Collection of energy (solar panels) • Storage of energy (battery) • Control of energy flow (charge controller) • Distribution of energy (wiring and switches) • Use of energy (appliances)

15. 2-3. Understanding a PV system through comparison with a rainwater collection system

16. Rainwater collection system

17. Solar PV system

18. Component Correlation • Solar panels –> Roof collection area • Charge Controls –> overflows and diverters • Battery –> water tank • Wiring –> pipes • Lights –> water tap

19. Rainwater Solar

20. Solar Panels • Produce Direct Current electrical energy by directly converting sunlight into electricity. Size of the panel is listed in Watts Peak, or Wp. This represents about the highest output possible from the panel under the best conditions. Note that the Watt rating for a panel is not an accurate measure of the Watts of load that can be used with that panel. Many other factors have to be considered and usually in the islands, the panel output is quite a bit lower than its rated value, typically between 60% and 70% of the Wp rating.

21. Controls • An electronic device is used to cut off charging to the battery when the battery is full. This is a charge controller • An electronic device is used to disconnect the battery from the load when the battery is getting low. This is a discharge controller.

22. Charge and discharge controllers • Prevents excessive loss of electrolyte from open cell batteries when approaching fully charged conditions • Prevents damage to sealed batteries due to excess charge • Prevents damage due to excessive depth of discharge The reliability of the controller is a major factor in the cost of SHS maintenance since batteries are easily damaged if the controller does not work correctly

23. Battery • Stores electricity. A battery is typically rated by its ability to store electricity, usually in Ampere Hours (Ah). • Almost always the battery is a lead-acid battery that uses the same basic technology as a car battery BUT • Car batteries do not last long in solar systems and generally it is much more cost effective to use batteries especially designed for solar use.

24. Wiring • Carries incoming energy from panels to battery • Carries outgoing energy from battery to appliances Wiring must be sized to have minimal losses since the solar electricity is limited and expensive. A common mistake with SHS is using wiring that is too small.

25. Adequate wire size is vital for proper operation of a PV system • The minimum size wire that normally should be used in a Solar Home System (SHS) installation between 50 Wp and 150 Wp is 12 AWG (or 2.5 mm2) to the lights and radio connection and 10 AWG (or 4 mm2) between the panels and the battery.