solar mooc off grid solar pv system design ryan light...
TRANSCRIPT
Solar MOOC Off Grid Solar PV System Design
Ryan Light, IRIS LLC
� Scenario � Load Analysis � Battery Sizing � Array Sizing � Charge Controller Sizing � Inverter Sizing � Lifestyle Changes
Welcome to Client A. In this scenario our clients are a retired couple who have built a 460 SqFt “Tiny Home” on a large acreage located outside of Ames, Iowa. Your site assessor has determined that the area is clear of obstructions and will have a daily access of 5.4 sun hours/day. They will live here year round as their primary residence.
� First and most important step in designing an off grid system.
� Take the time to learn/research the energy usage of each device.
� Take the time to learn/research the energy usage of the clients.
� Pay attention to phantom loads and seasonal usage.
� Measured Usage: 11.2kW/h per day � This gives us a starting point for the
batteries, solar panels and balance of systems components.
� Always attempt to talk the client into greater energy efficiency rather than a larger system.
� Determining Type of Battery to be Used: • Lead Acid Vented • Lead Acid Sealed • AGM • Gel Cells • Li-Ion, Nickel, and others
� Battery Voltages • 2V • 6V • 12V • Others
� Battery Amp/hours • Size Increase=$$$$ • Size Increase=Less Batteries
AC Ave Daily Load ÷
Inverter Efficiency +
DC Ave Daily Load ÷
DC System Voltage =
Ave Amp-‐hours per Day
11200 ÷ 0.9 + 0 ÷ 48 = 259 Ave Amp-‐hours
per Day × Days of
Autonomy ÷ Discharge Limit ÷ BaLery AH Capacity =
BaLeries in Parallel
259 × 3 ÷ 0.5 ÷ 350 = 4 DC System Voltage ÷ BaLery Voltage =
BaLeries in Series ×
BaLeries in Parallel = Total BaLeries
48 ÷ 12 = 4 × 4 = 18
� For this scenario the clients found a good deal on bulk Kyocera 240W Panels
� From the Battery Sizing Sheets we can determine the Array Sizing
Average Amp-‐hrs/day ÷
BaLery Efficiency ÷
Peak Sun Hrs/day =
Array Peak Amps
259 ÷ 0.8 ÷ 5.4 = 60 Array Peak
Amps ÷ Peak Amps/module =
Modules in Parallel
Module Short Circuit Current
60 ÷ 8.23 = 7 8.91 DC System Voltage ÷
Nominal Module Voltage =
Modules in Series ×
Modules in Parallel = Total Modules
48 ÷ 29 = 2 × 7 = 12
Total Daily Load Wh/
day ÷ Peak Sun Hrs/day ÷
BaLery Efficiency ÷
PV Temp Losses ÷
Derate Factor =
PV Array WaLs
11200 ÷ 5.40 ÷ 0.80 ÷ 0.90 ÷ 0.90 = 3201 PV Array WaLs ÷
STC WaL RaZng =
# of Modules Needed
3200 ÷ 245 = 13 Array
Nominal Volts ÷
PV Module Nominal Volts =
# of Modules in Series
150 ÷ 29 = 5
� Controller Types • MPPT (Max Power Point Tracking) • PWM (Pulse Width Modulation) • Single Stage & Shunt Controllers • Diversion Controllers
� For Controller Sizing we need information from the Panels and the Battery Bank
� Battery Bank info from earlier worksheet � Panel Info
Model Max Power
Voltage at Max Power
Current at Max Power
Maximum System Voltage
Open Circuit Voltage
Short Circuit Current
Series Fuse
Rating
Dimension (LxWxD) Weight
KD245GX-LFB
245 Watts
29.8 Volts
8.23 Amps 600V
36.9 Volts
8.91 Amps 15 Amps
65.43"x39"x1.8"
44.1 lbs
Module Short Circuit Current ×
Modules In Parallel × Safety Margin =
Array Short Circuit Amps
Controller Array Amps
8.91 × 3 × 1.25 = 33.4125 60 DC Total Connected WaLs ÷
DC System Voltage =
Max DC Load Amps
Controller Load Amps
÷ =
� Inverters are greatly varied � Stand alone inverters are selected by AC Watts,
System Voltage (Batteries), and Surge Watts
AC Total Connected WaLs DC System Voltage EsZmated Surge WaLs
11200 48 13000
� Clients must understand that they cannot live as if they are on Grid Power
� A backup system such as Wind, Generator, or Hydro is recommended.
� Install monitoring systems throughout � Understand the monitoring systems and
what they are telling you. � Decision for the night? What kind of
popcorn with the movie tonight…microwave or stove top?
