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

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Solar Home Systems(SHS) 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 Installation of SHS Preventive Maintenance Troubleshooting Contents

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic Principles of SHS

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Solar Photovoltaics for Rural Home Electrification

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, A Little History 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.

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Disadvantages of household solar 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

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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.)

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Rural Electrification Comparison Type First Cost per house Operating Cost Life Cycle Cost Power Availability and Reliability Home generatorLowVery High Low Village DieselMediumHigh Low to Medium Rural Grid Extension Very HighVery LowMediumVery High Solar Home system HighLowMediumHigh Solar Mini GridVery HighLowMediumVery High

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Solar Home Systems (SHS)

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Basic system

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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)

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Understanding a PV system through comparison with a rainwater collection system

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Rainwater collection system

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Solar PV system

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Component Correlation Solar panels –> Roof collection area Charge Controls –> overflows and diverters Battery –> water tank Wiring –> pipes Lights –> water tap

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, Rainwater Solar Rainwater Solar

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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.

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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.

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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.

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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.

e8 / PPA Solar PV Design Implementation O&M Marshall Islands March 31-April 11, 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 mm 2 ) to the lights and radio connection and 10 AWG (or 4 mm 2 ) between the panels and the battery.