DESIGN & SELECTION
OFF-GRID BATTERIES
Txt me your questions: Glen Morris 0419 299 140
SMART ENERGY COUNCILBATTERYSURVEYMay 2017
WORKPLACE HEALTH & SAFETY
SOLAR + BATTERY DESIGN
1. WORKPLACE HEALTH & SAFETY
▸Solar PV high d.c. voltages
▸ELV battery high short-circuit currents
▸LV battery high d.c. voltages similar to a PV array
▸Explosive gases (hydrogen + oxygen from PbA)
▸Chemical hazards (ie. acid spillage)
▸Fire hazard (self-ignition possible with lithium batteries)
SOLAR + BATTERY DESIGN
BATTERIES ARE HEAVY▸ use appropriate lifting and moving
equipment
▸ ensure structural integrity of mounting
surface
▸ hazardous good regulations may
effect transport options
▸ use insulated tools on exposed
terminals
SYSTEM CONFIGURATIONS
Txt me your questions: Glen Morris 0419 299 140
SOLAR + BATTERY DESIGN
2. SYSTEM CONFIGURATIONS
▸A.C. Coupled
▸D.C. Coupled
▸Single grid-port
▸Multi-port (grid and stand-alone)
▸D.C. - d.c. converter
▸ “AC Battery” (ie. Enphase & Powerwall 2)
Txt me your questions: Glen Morris 0419 299 140
SOLAR + BATTERY DESIGN
A.C. COUPLE SYSTEMS
Pro’s
▸easy to retrofit storage
▸ scales easily
▸no co-location with solar
▸ simple to install
▸ suits daytime energy use
Con’s
▸may not provide backup
▸adds to IES capacity
▸no solar charge when grid
down
▸energy meter required
Txt me your questions: Glen Morris 0419 299 140
Txt me your questions: Glen Morris 0419 299 140
BATTERY CHARACTERISTICS
SOLAR + BATTERY DESIGN
3. BATTERY CHARACTERISTICS
▸Cell v’s battery v’s BESS
▸Discharge rate (kW or A)
▸Charge rate (kW or A)
▸Amp-hour or Watt-hour capacity
▸State of Charge (SOC)
▸Depth of Discharge (DOD)
SOLAR + BATTERY DESIGN
3. BATTERY CHARACTERISTICS
▸Nominal voltage
▸Cutoff voltage
▸Absorb (or Boost) voltage
▸Float voltage
▸Self discharge rate
▸Design life (years or cycles)
SOLAR + BATTERY DESIGN
VOLTAGE DROOP WITH DEPTH OF DISCHARGE
SOLAR + BATTERY DESIGN
C RATES FOR BATTERIES
SOLAR + BATTERY DESIGN
VRLA SONNENSCHEIN (LEAD-ACID)
SOLAR + BATTERY DESIGN
VRLA CYCLE LIFE (SONNENSCHEIN A600)
SOLAR + BATTERY DESIGN
CAPACITY VS DISCHARGE RATE (SONNENSCHEIN A600)
BATTERY TECHNOLOGIES
SOLAR + BATTERY DESIGN
4. BATTERY TECHNOLOGIES
▸Lead-Acid (VRLA v’s flooded)
▸Lead-Carbon
▸Lithium ion (LiFePO4, NMC, NCA, LTO etc…)
▸Flow battery (Vanadium Redox & Zinc Bromine)
▸Hybrid ion (Aquion)
▸Hybrid Supercapacitors (Kilowatt Labs)
▸Nickel alkaline (NiCd)
▸Molten salt battery (Na-NiCl2 & NaS)
SOLAR + BATTERY DESIGN
COMPARISON OF LITHIUM ION BATTERY CHEMISTRIES
SELECTING & SIZING SPECIFIC LOADS
SOLAR + BATTERY DESIGN
5. SELECTING & SIZING SPECIFIC LOADS
▸Customer load energy requirement
▸Customer maximum power demand
▸Period of autonomy (if any)
▸PV supplied v’s battery supplied energy
▸ Inverter power rating
▸Self-use v’s Peak lopping v’s Backup
SOLAR + BATTERY DESIGN
BEST RESEARCH-CELL EFFICIENCIES
SELECTING & SIZING BATTERY
SOLAR + BATTERY DESIGN
6. SELECTING & SIZING BATTERY
▸Daily load energy required
▸Battery system voltage
▸Load sub-system efficiency
▸Amp-hour demand
(typically daily except if blackout protection)
▸Days of Autonomy (≥1day if off-grid)
▸Amp-hour capacity required @ Cx
SOLAR + BATTERY DESIGN
BATTERY SIZING EQUATIONS
▸A - daily load energy (Wh)
▸B - battery system voltage (V)
▸C - load sub-system efficiency (0.xx)(wiring, battery round-trip, and inverter efficiency)
▸D - Amp-hour demand = A ÷ B ÷ C
▸E - Amp-hour capacity = (D x DoA) ÷ DoD max.NB. to convert to kWh = (Ah x V) ÷ 1000
SOLAR + BATTERY DESIGN
BATTERY SIZING WORKED EXAMPLE
▸A - daily load energy 10,000Wh
▸B - battery system 48V
▸C - load sub-system efficiency 0.74
▸D - Amp-hour demand = 10,000 ÷ 48 ÷ 0.74
= 282Ah
▸E - Amp-hour capacity = (282 x 1) ÷ 0.9
= 313Ah @C10
= 313 x 48 = 15kWh (total capacity)
SIZING THE PV ARRAY
SOLAR + BATTERY DESIGN
7. SIZING THE PV ARRAY
▸Daily load energy requirement
▸Peak Sun Hours (PSH) of site
▸Derating for shade
▸PV sub-system efficiency
▸Load sub-system efficiency
SOLAR CHARGE CONTROLLERS
SOLAR + BATTERY DESIGN
8. SOLAR CHARGE CONTROLLERS
▸D.C. Coupled
▸A.C. Coupled
▸Micro-inverters
▸PV String considerations
▸Co-location v’s distributed location
▸ELV v’s LV d.c. charge controllers
▸Combo d.c. + a.c. (aka “Black Start”)
SELECTING, SIZING & PROGRAMMING INVERTERS
SOLAR + BATTERY DESIGN
9. SELECTING, SIZING & PROGRAMMING INVERTERS
▸Power ratings (continuous, short term, surge)
▸Battery system voltage (12/24/48/120/300+)
▸Temperature derating
▸Grid/Generator support
▸AC pass-through current
▸Software feature sets
SYSTEM WIRING
SOLAR + BATTERY DESIGN
10. SYSTEM WIRING
▸Maximum inverter current
▸Maximum charge controller current
▸D.C. loads or a.c. only
▸Cable selection (maximum CCC)
▸Ripple factor (worse with 1∅ or unbalanced 3∅)
▸Overcurrent protection selection
SYSTEM EFFICIENCY & PV/BATTERY YIELD
SOLAR + BATTERY DESIGN
11. SYSTEM EFFICIENCY & PV/BATTERY YIELD
▸PV to load efficiency
▸PV to battery efficiency
▸Battery to load efficiency
▸Grid to battery efficiency (and cost)
▸Levelised Cost of Electricity (Cost/Energy)
SYSTEM PHYSICAL LAYOUT
SOLAR + BATTERY DESIGN
12. SYSTEM PHYSICAL LAYOUT
▸Co-location
▸Manufacturer’s minimum clearances
▸Australian Standards requirements
▸Ambient thermal load + emitted heat
DOCUMENTATION & SIGNAGE
SOLAR + BATTERY DESIGN
13. DOCUMENTATION & SIGNAGE
▸AS/NZS 5033 requirements
▸AS/NZS 5139 requirements
▸AS/NZS 4777.1 requirements
▸Shutdown procedure
▸Location of signage
▸Electrical system schematics and equipment location plans
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