Transcript Solar Energy 20 October, 2010 Monterey Institute for International Studies Chris Greacen, Palang Thai.

Solar Energy
20 October, 2010
Monterey Institute for International Studies
Chris Greacen, Palang Thai
Outline
• The sun’s energy
• Passive solar, cooking, water heating, electricity
• Photovoltaics (PV)
– 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
– Components
• Lead acid batteries
• Charge controllers
• Inverters
– System sizing overview
World power
consumption:
15 TW
Thermal
Home heating/cooling
Cooking
Water heating
Electricity
Solar thermal electricity
Photovoltaics
COMMON GROUND:
“Zero Net Energy” Community
LOPEZ COMMUNITY LAND TRUST
Lopez Island, WA
Solar water heating
Generating electricity from sunlight
• Solar thermal electric
• Photovoltaics (PV)
How solar thermal electric works
www.greenterrafirma.com
Concentrating Solar
Power (Solar Thermal
Electric)
Solar Energy Generating Systems
(SEGS)
Kramer Junction, CA
www.greenterrafirma.com
How PV works
Current/Voltage (IV) curve for
solar cell
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
Pico-PV (small DC systems) Barefoot Power
0.5W
1.0W
1.5W
2.5W
5W
10W
15W
3.6V
12V
Off-grid system with AC & DC loads
Image source: Solar Energy International SEI
Small (300 Watts):
Solar Nexus
Bigger (3 kW):
Trace
Grid connected (AC)
Image source: Solar Energy International SEI
Net metering
Image source: Real Goods
Image source: Solar Energy International S
Image source: Solar Energy International SEI
Photovoltaics
Net Metering in the USA
www.dsireusa.org / April 2009
WA: 100
ME: 100
MT: 50*
ND: 100*
OR: 25/2,000*
VT: 250
MN: 40
WY: 25*
NV: 1,000*
CO: 2,000
CA: 1,000*
WI: 20*
IA: 500*
co-ops & munis: 10/25
UT: 25/2,000*
NM: 80,000*
AZ: no limit*
MI: 20*
IN: 10*
IL: 40*
MO: 100
OH: no limit*
WV: 25
KY: 30*
NC: 20/100*
OK: 100*
AR: 25/300
GA: 10/100
HI: 100
KIUC: 50
LA: 25/300
FL: 2,000*
State policy
Voluntary utility program(s) only
*
NH: 100
MA: 60/1,000/2,000*
RI: 1,650/2,250/3,500*
CT: 2,000*
NY: 25/500/2,000*
PA: 50/3,000/5,000*
NJ: 2,000*
DE: 25/500/2,000*
MD: 2,000
DC: 1,000
VA: 20/500*
40 states
& DC
have adopted a
net metering policy
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.
Feed-in tariffs
• long-term contracts for the electricity
produced
• purchase prices that are methodologically
based on the cost of renewable energy
generation.
Thai feed-in tariffs
Fuel
Adder
Additional for Additional for Years effective
diesel offsetting 3 southern
areas
provinces
Biomass
Capacity <= 1 MW
$ 0.015
$
0.030
$
0.030
Capacity > 1 MW
$ 0.009
$
0.030
$
0.030
Biogas
<= 1 MW
$ 0.015
$
0.030
$
0.030
> 1 MW
$ 0.009
$
0.030
$
0.030
Waste (community waste, non-hazardous industrial and not organic matter)
Fermentation
Thermal process
Wind
<= 50 kW
> 50 kW
Micro-hydro
50 kW - <200 kW
<50 kW
Solar
7
7
7
7
$ 0.074
$ 0.104
$
$
0.030
0.030
$
$
0.030
0.030
7
7
$ 0.134
$ 0.104
$
$
0.045
0.045
$
$
0.045
0.045
10
10
$ 0.024
$ 0.045
$ 0.238
$
$
$
0.030
0.030
0.045
$
$
$
0.030
0.030
0.045
7
7
10
Assumes exchange rate 1 Thai baht = 0.029762 U.S. dollars
Tariff
= adder(s) + bulk supply tariff + FT charge
Solar tariff = $0.24 + $0.05
+ $0.03
= $0.32/kWh
Generating Capacity supply to Grid
from 2006 - August 2009
การไฟฟ้ าส่ วนภูมภิ าค
PROVINCIAL ELECTRICITY AUTHORITY
MW
(31 August 2009)
Wind
350
Hydro
MSW
300
Solar
Cogeneration
www.pea.co.th
call center 1129
250
Biogas
Biomass
200
รวม
150
100
50
Year
0
2006
การไฟฟ้าส่วนภูมภิ าค
2007
2008
34
2009
Grid-connected Solar PV
• System size: 3 kW
Grid-connected
PV
Bangkok
Solar 1 Solar
MW PV
• Bangkok
• Project size: 1 MW
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
Seasonal array tilt
36.6 degrees
in Monterey
Peak Sun Hours
San Francisco:
5.4 PSH annual
average, tilt at
latitude*
1200
Watts/m²
1000
800
600
Peak Sun
Hours
400
200
6:00
8:00
10:00
14:00
*Source: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/sum2/23234.txt
16:00
18:00
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:
• Simple Payback:
6.5 years
• 10-year IRR: 14%
Note: project is real. Financials are conjecture.
10% discount rate, 4% inflation
40,000,000
20,000,000
0
(20,000,000)
baht
– TOTAL:
$0.33/kWh for 10
years
Discounted accumulated cashflow
(40,000,000)
(60,000,000)
(80,000,000)
(100,000,000)
(120,000,000)
2
4
6
8
10
Off-grid systems
DC SYSTEMS
SYSTEMS WITH AC LOADS
Thai solar home systems
Solar for computer training centers
in seven Karen refugee camps
Thai-Burma border
•1 kW PV hybrid with diesel generator
•Each powers 12 computers
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
+
– Negative electrode
Lead (Pb).
– Positive electrode
Lead dioxide
(PbO2).
• Electrolyte
– Sulphuric Acid
(H2SO4).
• Sulfation, equalizing
H2SO4
-
Lead Acid Batteries
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.
• Deep cycle – e.g. golf cart and forklift
– Deep cycle: 60% to 80% DOD
– Thick plates or tubes withstand deep discharge.
Lead Acid Battery Cycle Life
Cycles to 80% capacity
• Number of cycles to a particular DOD.
• Cycle life decreases with increasing DOD.
• Sulphation is the main cause of failure.
4000
Deep cycle battery
2000
Car battery
0%
50%
100%
Depth of Discharge (DOD)
Off-grid system components
Charge Controller
Charge controller
Solar panel
Loads
Battery
Charge controller
• Ensures that battery is not overcharged
• 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
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
1. Load analysis
2. Specify capacity of solar panel, battery,
charge controller, and inverter (if
necessary)
3. Wire sizing
ITEM
Ceiling Fan
Clock Radio
Clothes Washer
Electric Clock
Iron
Sewing Machine
Table Fan
Refrigerator/Freezer (19 Cu Ft)
Refrigerator/Freezer (12 Cu Ft)
Refrigerator/Freezer (4 Cu Ft)
Blender
Coffee Pot
Microwave (.5 Cu Ft)
Electric Range
Incandescent (100W)
Incandescent (60W)
Compact Fluorescent (60W equivalent)
Incandescent (40W)
Compact Fluorescent (40W equivalent)
CB Radio
CD Player
Cellular Phone
Computer Printer
Computer (Desktop)
Computer (Laptop)
Stereo (average volume)
Stereo (Large Full volume)
TV (12 inch black and white)
TV (19 inch color)
VCR
Band Saw (14”)
Circular Saw (7.25”)
Disc Sander (9”)
Drill (1/4”)
LOAD(Watts)
10-50
5
1450
4
1500
100
10-25
1000 Wh/day
470 Wh/day
210 Wh/day
350
1200
750
2100
100
60
16
40
11
10
35
24
100
80-150
20-50
15
150
15
60
40
1100
900
1200
250
Load analysis
Watt
Watts Watts Hours per hours
each total
day
per day
Qty
Load
2
13
26
4
104
50
50
5
250
1
light
laptop
computer
tv (19 inch
color)
60
60
1
60
1
DVD player
30
30
1
30
1
circular saw
900
900
0.25
225
1
blender
350
350
0.25
87
1
Totals
1416
756
Inverter
Load analysis
Watt
Watts Watts Hours per hours
each total
day
per day
Qty
Load
2
13
26
4
104
50
50
5
250
1
light
laptop
computer
tv (19 inch
color)
60
60
1
60
1
DVD player
30
30
1
30
1
circular saw
900
900
0.25
225
1
blender
350
350
0.25
87
1
Totals
1416
756
Solar
panels,
batteries
Load analysis
Watt
Watts Watts Hours per hours
each total
day
per day
Qty
Load
2
13
26
4
104
50
50
5
250
1
light
laptop
computer
tv (19 inch
color)
60
60
1
60
1
DVD player
30
30
1
30
1
circular saw
900
900
0.25
225
1
blender
350
350
0.25
87
1
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
2 light
1 laptop computer
1 tv (19 inch color)
1 DVD player
1 circular saw
1 blender
Totals
Watts each
Watts total
13
50
60
30
900
350
Hours per day
26
50
60
30
900
350
1416
Watt hours
4
5
1
1
0.25
0.25
Solar panel derating
85%
Battery efficiency
85%
Wiring efficiency
97%
Inverter efficiency
90%
Total efficiency
63%
Total adjusted watt hours per day (= watt hours / total efficiency)
Nominal system voltage
Adjusted amp-hours per day (= adjusted watthours / system voltage)
Peak Sun Hours (average)
Amps of solar power required (=Adjusted amp-hours / PSH)
Imp (amps) per solar panel (Astopower PV120. 120 watt. Imp = 7.1, Isc = 7.7)
Number of solar panels (= amps solar required / amps per panel)
Rounded up…
Isc per panel
Minimum controller current (amps) = 1.25 x Isc
Maximum number of days of autonomy
Max allowable depth of discharge
Battery ampere-hours (= adjusted amphours x days of autonomy / allowable depth of discharge)
104
250
60
30
225
87.5
756.5
1,199
12
99.95
5.4
18.51
7.10
2.61
3
7.7
29
3
0.5
600
Wire sizing
• Voltage drop – how much power is lost to heat
V=IR
• 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
2. Battery over-charged.
Electrolyte level drops
and plates are exposed to
air. Battery fails.
1
2
User error: Controller bypass
leads to burned diode
1. Villager bypasses
broken controller
and charges battery
directly from PV
2. One mistake of
reverse battery
polarity blows up
bypass diode in PV
junction box,
melting junction
box.
2
1
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
Tax payers
$
Ministry of
Interior
$
warranty
PEA
$
Installation
company
SHS
End users
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
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
Thank you
[email protected]
This presentation available at:
www.palangthai.org/docs