Solar Electricity 14 April, 2009 Monterey Institute for International Studies Chris Greacen, Palang Thai Thursday night at 6pm talk on more of our work on Burma/Thai border, policy and energy politics in Thailand

Palang Thai พลังไท Thailand NGO Objective: Key approaches: พลัง (palang): n 1. Power. 2. Empowerment. ไท (thai): adj. 1. Independence. 2. Self-reliance Thailand NGO Objective: To ensure that the transformations that occur in the region's energy sector: augment, rather than undermine, social and environmental justice and sustainability. Key approaches: We teach hands-on energy technology We help draft policies We comment on projects and plans We advocate reform in energy planning processes & regulatory regime 1:20 Palang Thai is a husband & wife non-profit. The name Palang Thai is kind of a play on words. Palang has two meanings in Thai language – “power” in the sense of energy, but also “empowerment” in the sense of impowerment of groups of people. “Thai” also has two connotations. It sounds like the “thai” in Thailand, but spelled this way in Thai script it actually means “independence” or “self-reliance”. In practice, we work to ensure that changes that are happening in the region’s energy industry support rather than erode social and environmental justice. We teach hands-on technical skills to local people to build, operate, and repair clean energy alternatives We draft policies so that small green energy options can compete on a level playing field with conventional fossil fuel options We scrutinize the economic appraisal of mega projects. I’m going to focus on the drafting policy side – some of which is work we began before we decided to call ourselves “palang thai.”

Outline Photovoltaics (PV) Basic types of solar electric systems Basic market trend How PV works Basic types of solar electric systems Grid-connected systems Components Net metering Calculating simple payback (with detour on Peak Sun Hours, array tilt, shading) Off-grid Lead acid batteries Charge controllers Inverters System sizing overview When folks talk about renewable energy, you often hear about the technology, or the costs. For widespread renewable energy to take place, however, regulations are necessary that make it possible for renewable energy to integrate with the grid. The story I’m going to tell is a story about those regulations – and how we helped make them happen in Thailand. I’ll start with ‘what is net metering’. Most of you are probably already familiar with these regultations, but I mention them because the Thai regs are essentially based on net metering regs, and are ‘net metering on steriods’.

Photovoltaics

Not to be confused with Concentrating Solar Power (Solar Thermal Electric) I won’t talk about concentrating solar thermal much, although it is a very promising techology. For large-scale applications it is cheaper than photovoltaics.

How PV works

Off-grid array-direct system Image source: Solar Energy International SEI

Off-grid direct current (DC) system with batteries Image source: Solar Energy International SEI

Off-grid system with AC & DC loads Image source: Solar Energy International SEI

Grid connected (AC) Image source: Solar Energy International SEI

Net metering Image source: Real Goods

Image source: Solar Energy International SEI

Image source: Solar Energy International SEI

40 states & DC have adopted a net metering policy Net Metering in the USA www.dsireusa.org / April 2009 WA: 100 ME: 100 MT: 50* ND: 100* VT: 250 NH: 100 OR: 25/2,000* MN: 40 MI: 20* MA: 60/1,000/2,000* WY: 25* WI: 20* RI: 1,650/2,250/3,500* IA: 500* IN: 10* CT: 2,000* NV: 1,000* CO: 2,000 co-ops & munis: 10/25 OH: no limit* NY: 25/500/2,000* IL: 40* PA: 50/3,000/5,000* UT: 25/2,000* WV: 25 MO: 100 KY: 30* NJ: 2,000* CA: 1,000* NC: 20/100* DE: 25/500/2,000* NM: 80,000* OK: 100* MD: 2,000 AZ: no limit* AR: 25/300 DC: 1,000 GA: 10/100 VA: 20/500* LA: 25/300 HI: 100 KIUC: 50 FL: 2,000* 40 states & DC have adopted a net metering policy State policy Voluntary utility program(s) only * State policy applies to certain utility types only (e.g., investor-owned utilities) Note: Numbers indicate system capacity limit in kW. Some state limits vary by customer type, technology and/or system application. Other limits may also apply.

Grid-connected Solar PV There is more than enough rooftops in the country to power Thailand’s peak load. Here’s a photo of a typical 3 kW solar electric system sold in Thailand. If one of these was installed on 58% of Thai households, it could produce enough electricity to meet Thailand’s peak load. They’re expensive, though. System size: 3 kW

Grid-connected Solar PV Bangkok Solar 1 MW PV Grid-connected Solar PV Bangkok Project size: 1 MW

How do you estimate how much electricity it will produce How do you estimate how much electricity it will produce? How long does it takes to pay for itself?

Solar panel produces more power when it faces the sun

Facing solar panels at the sun is made difficult by the fact that, from our perspective, the sun moves. It rises in the east in the morning and sets in the west in the evening. And it changes seasonally – low in the sky during the winter, higher during the summer, and medium in autumn and spring.

Seasonal array tilt 36.6 degrees in Monterey

Another obvious consideration is that solar panels make less electricity when they’re shaded. The strange thing about most solar panels is that it is remarkable how much less electricity they produce. It’s not like a solar water heater, where 10% shading will lead to 10% reduction in solar energy absorbed. In most PV panels, full shading of 10% of the solar panel leads to about 90% reduction in power output. So when I work on solar electric systems I can get very picky about shading from a little bit of grass, from twigs, leaves, bird poop.

Peak Sun Hours Watts/m² San Francisco: 5.4 PSH annual average, tilt at latitude* 1200 1000 800 Watts/m² 600 Peak Sun Hours 400 Assuming there’s no shading (horizon to horizon sun). Assuming a proper array angle, then sun energy absorbed during the day follows the black curve – with relatively little light intensity in the morning and evening, but more in the afternoon. Since math with curves like this can be a pain, solar people early on adopted a metric referred to as ‘peak sun hours’ that conceputally makes the curve into a rectangle. You squeeze all sunlight energy into a few hours of noon-time peak sun equivalent, that is peak hours. The area under the curve is equal to the area of the rectangle 200 6:00 8:00 10:00 14:00 16:00 18:00 *Source: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/sum2/23234.txt

annual average peak sun hours (PSH)

Anacortes, WA = 3.7 PSH per day annual average San Francisco = 5.4 PSH

Energy produced kWh per year = (PSH) x (peak kW of array) x (solar panel derating) x (inverter efficiency) x 365 Example: 5.4 hours x 2.5 kW x 85% x 95% x 365 = 4000 kWh

Grid-tied solar simple payback period Installed cost  $7K to $9K per kW 2.5 kW * $8,000 = $20,000 Value of annual electricity offset: $0.25/kWh * 4000 kWh/year = $1000/yr Simple Payback: $20,000 / $1000/yr = 20 years (assuming no subsidies)

Financial sketch: MW-scale solar project in Thailand Project size: 1 MW Cost estimate: $4 million Tariffs: TOTAL: $0.33/kWh for 10 years Simple Payback: 6.5 years 10-year IRR: 14% Note: project is real. Financials are conjecture. 10% discount rate, 4% inflation

Off-grid systems DC SYSTEMS SYSTEMS WITH AC LOADS

(0.25) Here medics are setting a solar electric system up in a remote clinic. Patients treated in a clinic with solar electricity we provided.

Thai solar home systems The Thai government last year started a massive solar home system program, providing a solar panel and battery for each unelectrified household in the country. There’s over 203,000 systems, installed at a cost to tax payers of about $200 million. These systems have had some sustainabilty problems because equipement that was used was not that good. But it represents an admirable effort nonetheless.

Solar for computer training centers in seven Karen refugee camps Thai-Burma border 1 kW PV hybrid with diesel generator Each powers 12 computers Solar now powers computer training centers in seven refugee camps.

Off-grid system components Charge controller Solar panel Loads Battery

Off-grid system components Charge controller Solar panel Loads Battery

Lead Acid Batteries - + Two electrodes Electrolyte Negative electrode Lead (Pb). Positive electrode Lead dioxide (PbO2). Electrolyte Sulphuric Acid (H2SO4). Sulfation, equalizing PbO2 Pb Separator H2SO4

Lead Acid Batteries Composed of plates of lead and lead oxide.

L-16 battery bank

Flooded Lead Acid Advantages: Disadvantages: Water can be added. Cheapest. Most common. Disadvantages: Can spill. Hydrogen is vented during charging. More prone to vibration damage.

Valve Regulated Lead Acid Maintenance Free Similar to Flooded Lead Acid. Gel Silica Gel contains the electrolyte AGM (Absorbed Glass Mat) Electrolyte is Absorbed in a Fiber Glass Mat

Lead Acid Battery Types Starting, Lighting and Ignition (car battery) Shallow cycle: 10% DOD Deep discharge drastically reduces battery life. Thin plates maximize surface area and current. Traction – golf cart and forklift Deep cycle: 60% to 80% DOD Thick plates or tubes withstand deep discharge.

Lead Acid Battery Cycle Life Number of cycles to a particular DOD. Cycle life decreases with increasing DOD. Sulphation is the main cause of failure. 0% 50% 100% Depth of Discharge (DOD) Car battery Deep cycle battery 2000 4000 Cycles to 80% capacity

Battery Capacity Given in Amp hours [Ah] for a particular discharge rate at 25°C. Empty is usually defined as 10.5 Volts. Usable capacity depends on actual discharge rate and temperature.

Charge and Discharge Rates Written Ct or C/t Where t = Time = Capacity[Ah]/rate[A] Examples: A 200 Ah battery at 10 amps takes 20 hours and has a C/20 rate. A 200 Ah battery at 2 amps takes 100 hours and has a C/100 rate.

Capacity and Discharge Rate Lead sulphate forms at both electrodes. H2SO4 turns to water. Discharge rate affects usable capacity. 12.0 C/100 Battery Voltage C/10 10.5 0% 50% 100% Depth of Discharge

Charging Lead Acid Battery Voltage is a function of state of charge and charge rate Lead dioxide and lead form at electrodes. H2SO4 increases. Lower charge rates avoid gassing. 16.2 C/10 Battery Voltage 14.4 C/100 12.0 100% 0% 50% State of Charge

Equalizing Charge Only Applicable to Flooded Style Batteries Provide a charged battery with a high terminal voltage, ~16V. High voltage causes the battery to “boil”. Lead sulfate is dislodged from plates. Bubbling action mixes up the stratified layers Equalize charge for a few hours at a time

Off-grid system components Charge Controller Charge controller Solar panel Loads Battery

Charge controller Ensures that battery is not over-charged For small DC systems, often features a Low Voltage Disconnect (LVD) to ensure that battery is not over-discharged Fancy big ones sometimes have Maximum Power Point Tracking (MPPT) that squeezes more power out of solar panels

Three Stage Charging Reduces the charge rate as SOC increases. Bulk Charge Absorption Float Current Voltage Time 15 V C/20 C/100

Off-grid system components

Inverter Converts Direct Current (DC) to Alternating Current (AC) to power ‘regular’ loads Sometimes includes battery charger Typically can surge to 3X rated power

Inverter Waveforms Square Wave Modified Square Wave Sine Wave

Back-of-the-envelope steps for designing an off-grid solar electric system Load analysis Specify capacity of solar panel, battery, charge controller, and inverter (if necessary) Wire sizing

ITEM LOAD(Watts) Ceiling Fan 10-50 Clock Radio 5 Clothes Washer 1450 Electric Clock 4 Iron 1500 Sewing Machine 100 Table Fan 10-25 Refrigerator/Freezer (19 Cu Ft) 1000 Wh/day Refrigerator/Freezer (12 Cu Ft) 470 Wh/day Refrigerator/Freezer (4 Cu Ft) 210 Wh/day Blender 350 Coffee Pot 1200 Microwave (.5 Cu Ft) 750 Electric Range 2100 Incandescent (100W) Incandescent (60W) 60 Compact Fluorescent (60W equivalent) 16 Incandescent (40W) 40 Compact Fluorescent (40W equivalent) 11 CB Radio 10 CD Player 35 Cellular Phone 24 Computer Printer Computer (Desktop) 80-150 Computer (Laptop) 20-50 Stereo (average volume) 15 Stereo (Large Full volume) 150 TV (12 inch black and white) TV (19 inch color) VCR Band Saw (14”) 1100 Circular Saw (7.25”) 900 Disc Sander (9”) Drill (1/4”) 250

Load analysis Qty Load Watts each Watts total Hours per day Watt hours per day 2 light 13 26 4 104 1 laptop computer 50 5 250 tv (19 inch color) 60 DVD player 30 circular saw 900 0.25 225 blender 350 87   Totals 1416 756

Load analysis Inverter Qty Load Watts each Watts total Hours per day Watt hours per day 2 light 13 26 4 104 1 laptop computer 50 5 250 tv (19 inch color) 60 DVD player 30 circular saw 900 0.25 225 blender 350 87   Totals 1416 756

Solar panels, batteries Load analysis Qty Load Watts each Watts total Hours per day Watt hours per day 2 light 13 26 4 104 1 laptop computer 50 5 250 tv (19 inch color) 60 DVD player 30 circular saw 900 0.25 225 blender 350 87   Totals 1416 756

Solar panel derating: 15% Loss from Wiring: 3% Loss from Battery: 15%

How many solar panels? What size controller? Battery size? Qty Load Watts each Watts total Hours per day Watt hours 2 light 13 26 4 104 1 laptop computer 50 5 250 tv (19 inch color) 60 DVD player 30 circular saw 900 0.25 225 blender 350 87.5   Totals 1416 756.5 Solar panel derating 85% Battery efficiency Wiring efficiency 97% Inverter efficiency 90% Total efficiency 63% Total adjusted watt hours per day (= watt hours / total efficiency) 1,199 Nominal system voltage 12 Adjusted amp-hours per day (= adjusted watthours / system voltage) 99.95 Peak Sun Hours (average) 5.4 Amps of solar power required (=Adjusted amp-hours / PSH) 18.51 Imp (amps) per solar panel (Astopower PV120. 120 watt. Imp = 7.1, Isc = 7.7) 7.10 Number of solar panels (= amps solar required / amps per panel) 2.61 Rounded up… 3 Isc per panel 7.7 Minimum controller current (amps) = 1.25 x Isc 29 Maximum number of days of autonomy Max allowable depth of discharge 0.5 Battery ampere-hours (= adjusted amphours x days of autonomy / allowable depth of discharge) 600

Wire sizing Voltage drop – how much power is lost to heat V = I R Ampacity – how much current the wire can safely conduct

12 Volt 2% Wire Loss Chart Maximum distance one-way in feet Multiply distances by 2 for 24 volts and by 4 for 48 volts. http://www.affordable-solar.com/wire.charts.htm

Wire sizing Typically aim for 3% or less loss http://www.csgnetwork.com/voltagedropcalc.html

Ampacity table

PV system errors

User error: bypassed controller  battery overcharge 1 Villager bypasses broken controller and charges battery directly from PV Battery over-charged. Electrolyte level drops and plates are exposed to air. Battery fails. 2

User error: Controller bypass leads to burned diode 1 User error: Controller bypass leads to burned diode Villager bypasses broken controller and charges battery directly from PV One mistake of reverse battery polarity blows up bypass diode in PV junction box, melting junction box. 2

Problems found during training surveys User error: Villager used inefficient 60 W light bulb

Installation error: Battery failure caused by solar panel installation in shady location 14:00 Saw Kre Ka village, Tha Song Yang District

Installation error: Bad panel locations

“The Service & Support Department is like the guy in the parade who walks behind the elephant with a broom and a big bucket”

Existing linkages $ $ $ SHS Tax payers Ministry of Interior warranty PEA $ Installation company SHS End users

What happens when systems fail? Missing linkages Tax payers $ Ministry of Interior $ warranty PEA $ Installation company SHS End users What happens when systems fail? There is no feedback loop from the end users to installation company, PEA, government or taxpayers

Missing linkages $ $ $ SHS Tax payers $ Ministry of Interior $ warranty PEA $ Installation company SHS End users Feedback on status of systems, failure modes, successful interventions Warranty awareness Self-help: local technicians + user training

SHS Warranty Postcards with warranty and maintenance information could be distributed by Tambons Idea presented at meeting with DLA (Department of Local Administration)

BGET SHS trainings in Tak province