1. 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

2. 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.”

3. 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’.

4. Photovoltaics

6. 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.

7. How PV works

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

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

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

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

12. Net metering
Image source: Real Goods

13. Image source: Solar Energy International SEI

14. Image source: Solar Energy International SEI

15. 40 states & DC have adopted a net metering policy
Net Metering in the USA
/ 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.

16. 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

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

18. 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?

19. Solar panel produces more power when it faces the sun

21. 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.

22. Seasonal array tilt
36.6 degrees in Monterey

23. 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.

24. 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:

25. annual average peak sun hours (PSH)

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

27. 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

28. 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)

29. 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

30. Off-grid systems
DC SYSTEMS
SYSTEMS WITH AC LOADS

31. (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.

32. 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.

33. 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.

34. Off-grid system components
Charge controller
Solar panel
Loads
Battery

35. Off-grid system components
Charge controller
Solar panel
Loads
Battery

36. 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

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

38. L-16 battery bank

39. 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.

40. 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

41. 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.

42. 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

43. 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.

44. 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.

45. 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

46. 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

47. 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

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

49. 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

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

51. Off-grid system components

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

53. Inverter Waveforms
Square Wave
Modified Square Wave
Sine Wave

54. 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

55. 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

56. 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

57. 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

58. 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

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

60. 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 PV 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

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

62. 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.

63. Wire sizing Typically aim for 3% or less loss

64. Ampacity table

65. PV system errors

67. User error: bypassed controller  battery overcharge1
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

68. User error: Controller bypass leads to burned diode1
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

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

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

71. Installation error: Bad panel locations

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

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

74. 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

75. 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

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

77. BGET SHS trainings in Tak province