OffTheGrid

Ian Harrison
Synergineering Consultancy®
© September 2015
OFF THE GRID
ENGINEERING:
A Systems Engineer Approach
to building an Off the Grid
Home
As presented
 Engineers Australia
 ITEE Canberra Branch
 15 Sep 15

CONTEXT
Sep-15IAN HARRISON : SYNERGINEERING
• In 2013 we purchased 9.5 Hectares of Land at Manar.
• Half timber gentle slope, half level creek flat (cleared)
• One small (healthy) Dam
• No other existing structures etc other than fences.
• Services available
• Public Road frontage (front gate) of 10m.
• Telstra pit at front gate
• Power is 1.5km away (easement allocated)
• Abundant Natural Resources
• Rain
• Sunshine
• Wind
• Firewood
• Fresh Air
• Wildlife
• Fertile Soil

GOALS / NEEDS /CONSTRAINTS
• Build a new home for my Wife and I
• Comfortable
• Suit us for 20 years
• Lower our cost of living
• Future proof from many of those ever increase costs like energy, water etc
• Grow/raise a lot of what we eat.
• Enjoy the natural environment and quiet
• Constraints
• Budget (limited but not tight)
• Timeline (a few years)
• Local Planning

PRESENTATION
• Focus on the provision of Services
• Electric Power
• Heating
• Water
• Sewage
• The design interdependencies between the above and
• Us
• Buildings/structures
• Land Use
• External Influences
• Authorities

• $ 6,000 (PV panels @ 80c/W + mount)
• $ 3,000 MPPT Chargers
• $30,000 (German SLA @ 30% DoD)
• $ 6,000 (SMA Charger invertor)
• $10,000
• $15,000 (180kL storage)
• $ 1,000 (a pressure pump)
• $30,000 (part of house build)
• Electric Power
• 6kW Solar
• 21 kWh usable Storage (3 days)
• 6kW AC power generation with
• 12kW surge (few seconds)
• Sewage
• Potable Water (tanks/pumps)
• Irrigation Water
• Heating (Space, Water, Cooking)
QUICK LOOK / ROUGH COSTS
Requirement Rough Cost

COST DRIVERS (HEATING)
• Heating
• Half of cost is hydronic in slab heating with Buffer tank
• this was more a personal Decision (winter warmth etc)
• Alternative heat source to wood/solar was Ground Source Heat Pumps which
impacted on Power Generation.
• double PV array and AC Power Generation (+$12,000)
• Ground Source Heat pumps (+$6,000)
• Savings (-$13,000) from Wood/Solar system
• So Electric based heating adds $5,000, so not cost effective
• And noisy, and shorter life for some parts
• NB does not impact Battery as a Heat Storage Tank is used as a buffer.

COST DRIVERS (POWER STORAGE (1))
• Power Storage $25,000 (+- $10,000).
• Existing Technologies
• Seal Lead Batteries (AGM or GEL)
• 30% DoD to give 10 year life (so needs a 70kWhr Battery)
• Chinese @ $18,000 up to German @ $30,000
• Lithium Ion Batteries
• 80% DoD to give a 10 year life (so needs a 27kWhr Battery)
• Chinese @ $20,000 up to $35,000 for Western Suppliers.
• Water (pump Storage)
• Not viable, Over 800kl over 10m drop available.
• $100,000 just for tanks! (or a higher hill)

POWER STORAGE (2)
• Emerging Technologies
• Aquious Hybrid Ion
• Rechargable Zinc-Air (Zynth)
• Quoting target costs of US$0.8/kwHr in a few years ($16,800)
• At time (mid 2014) both were
• 100% DoD, life >>10 years
• Robust technologies
• Low Toxicities
• Compatible with many Chargers & Inverters
• Currently marketing to Grid Storage market (alternative to Peaking Power
Stations).
• No information of when available to Retail market.
• Then put on watch for changes in availability

POWER STORAGE ALTERNATIVES
• Alternatively reduce demand on Electric Power at night and overcast days:
• Target 3 days of poor weather
• Assumes no power gathered (conservative as cloudy day still produces)
• General Power Efficiency
• LED lighting throughout (no longer cost prohibitive and very effective)
• 12V Power was discounted due to 100m between Battery and House
• Induction Cooktops (only used in Summer, less critical)
• Source high efficiency appliances where possible
• Load Management
• Non critical loads moved to Sunny Days
• Water transfer (Header tank used with several weeks of water)
• Septic System pump out
• Heating Circulation Pumps (heat storage in tank and floor)
• Pool Filtration pump

DESIGN DECISIONS (FROM POWER SYSTEM)
• Heating (Space, Water, Cooking)
• Hydronic in slab (Concrete) heating
• 2000L Heat Storage tank (Hydronics and Hot Water)
• 20kW back boiler on wood stove (prime winter heat source)
• 30-40 Solar tubes on roof (prime summer heat source)
• Induction cooktop, two spot (summer cooking)
• Excess heat can be sunk into pool.
• High levels of insulation in house (windows, walls, ceiling, under slab).
• Solar Passive design elements.

• Potable Water (Rainwater)
• Header Tanks for water supply (6-8m head to house)
• 20kL tank means water transfer only once every few weeks
• When excess power (solar) available.
• Small transfer pump 300W, low impact on inverters.
• House plumbing needs careful design for low Head pressure.
• Larger Bore pipes (reduce flow looses)
• Irrigation Water (Dam water)
• Only used in Summer (mainly) when excess energy available
• Pressure pump used
• with pressure tank (reduced duty cycle)
• Lower cost (1 pump, no storage tanks or 150m piping 150m to elevated spot).

• Sewage (Onsite Sewage Management System (OSMS) in council speak
• Choice of Worm Farms vse 2/3 stage treatment type systems.
• Selected Worm Farm because
• Lower ongoing Power (2W monitor/Alarm vse a Fans)
• Same peak power for transfer pump
• Lower Maintenance (2 yearly inspection vse 3 monthly replenishment)
• No need for Chlorine
• Otherwise similar demands
• BUT
• Emergent ‘requirements’ from Sydney Catchment Authority meant
• Had to have its own Power Supply (PV, battery, Inverter, Gen backup!) (+$2,500)
• Treated Effluent had to be disposed into a soak/wicking system
• Could not be reused (ie to water fruit trees) (+ $7,000)

POWER SYSTEM MODELLING (1)
• Power Demand
• Excel Tables (several sheets on www.)
• Captured all Power loads, size, utilisation
• Enhanced to capture
• Summer vse Winter Utilisation
• Discretionary (off peak), controlled, uncontrolled
• Determined for Winter and Summer
• Peak Power (6-8 kW)
• Daily Power Consumption (typical and ‘reduced’) (typ 7kWhr/day).
• Compared with ‘typical’ from www. and in same ball park (generally lower).

• Power Generation Potential
• Solar PV
• www.PVoutput.org
• Actual outputs of real PV systems in area
• Selected a large PV with similar angles and several years data to feed into
a model of system to access battery DoD.
• Pvwatts.nrel.gov
• Data based on Canberra Solar levels
• Calculates kWh collected:
• Monthly (web or CSV)
• Hourly (CSV) assumes this is one year of real data

• Modelled a system with 6kW array and 75kWhr SLA Battery
• Used 3 years of Data from PVOutput (hourly)
• Correct for Tilt Angle and Array size
• Battery DoD went over 30% only a few time / year.
• Battery DoD did not exceed 50%.
• A good compromise
• Initial modelling was conducted 12 months ago and data since lost!
• Sorry, no nice graphs to show.
• Will rebuild when time allows.
• Repeated this model this month with final System configuration

FINAL SYSTEM
• PV Array
• 24 of Canadian Solar Poly CS6P 260W panels
• Plus two spares, currently on Sewage Power System
• PV Mount
• Custom Designed Ground mounted Frame
• Two arrays each of 2 rows of 6 portrait orientated panels
• Tilt about EW axis from 50° North to 50° South (for maintenance)
• Gal Steel Frame with Titan Solar rails.
• Flexibility to set optimum array angle
• Initially set for 45° for
• optimum winter collection (20kWhr per day) whilst
• adequate summer collection (32kWhr per day)
Selection Criteria
 Good $/W
 Good Reputation

FINAL SYSTEM (2)
• AC verse DC coupling
• Initially was going DC coupled for efficiency
• Changed to AC coupling for efficiency and convenience
• Solar Inverters can handle a string of 12 PV (vs most MPPT chargers can handle no
more than 6 PV panels)
• Doubles Cabling between PV and MPPT inverter/Charger (20-25m per array)
• AC couple provides increase instantaneous power (when sun shining)
• Solar Inverters (Grid inverters to those on Grid)
• 2 of SMA Sunny Boy 3000TL (each 3kW AC power)
• Each having one string of 12 PV panels.
• Battery Inverter/Charger
• 1 of SMA Sunny Island 8.0H
• 6kW Continuous, 8 kW (30min), 12kW (5 secs)
Selection Criteria
 Good Reputation
 Functionality
 Grid/interconnected

FINAL SYSTEM (3)
• Batteries
• Selected 48V battery bank (early decision)
• Lower currents than lower voltages Batteries → less losses
• Limited equipment available for higher voltages (like 96V or
120V DC)
• Excellent life (Predicted?)
• 12 of Aquion Energy S20-P08O AHI Battery Stacks
• They are now available in Australia
• Rev P with lower internal Resistance and lower cost
• Each stack is 48V @ 1.2kWhr to 2.4 kWhr
• 15 to 28 kWhr at 100% DoD
• More cost effective than Lithium or SLA
• Easily expanded… add stacks in multiples of 1 (2kWhr)
Selection Criteria
 Good $/kWhr/life
 Expandability

CURRENT STATE
• All Major Equipment on site
• Except Battery (in transit from USA, due November)
• Conduits in ground (20+m from shed to PV)
• Need to
• Weld A frames for PV mount, then assemble
• Clear shed for Batteries and Inverters
• Currently temporary workshop
• Find a electrician
• Connect it all together

FUTURE
• Once house is built and we are living in it (mid ‘16)
• Assess systems performance and Adjust
• PV array angle (move it twice a year is an option but unlikely)
• Battery Size
• Can we achieve 3 days over cast?
• Add more battery stacks
• Add a wind generator for power source diversity
• 2 to 3kW Vertical Axis Turbine (works better in dirty air)
• Can we deliver enough power
• Need 3 or 4 more stacks for 12kW peak of SI 8.0H
• Efficiency
• Controllers to automatically shed/control non critical loads
• Learning to live Off Grid

SEWAGE SYSTEM POWER SUPPLY
• Sydney Catchment Authority required a Separate Power System
• Because we are off-grid!
• Requirements
• Delivery 2W continuous and 400W for 2 minutes a day
• 61kWhr/day, 400W continuous, 600W peak (pump start)
• Mk 1 (el cheapo)
• 600 W Modified Sinewave inverter (Projecta)
• 7A 240V Charger (Projecta) for backup charging
• 12V x 165Ahr AGM Battery (594 Whr usable Capacity)
• 10W Solar Panel and Charger (part of Solar HWS) initially
• Failed because of
• pump change (750W) and
• Inverter standby current (480Whr/day)

Sewage System Power Supply (2)
• Mk 2
• 2 of CS6P 260W PV panels (only needs one)
• Victron Energy Blue Solar 100/15 MPPT
Charge Controller
• Victron Energy Multiplus C24/1600/40 Inverter
charger
• 1.3kW cont 3kW peak Inverter.
• 10W or 3W no load power
• 4 of 125Ahr AGM Battery (24V at 250Ahr,
1.2kWhr usable) (only need 2)
• Can run/charge from main Power system as
backup
• Now fully operational except backup

FINALLY
• Watch us produce and burn energy on PVOutput
• Name “WombatHollow”
• Once installed and we have Internet (after Xmas?).
Ian Harrison
Synergineering Consultancy
Synergineering@iinet.net.au

OffTheGrid

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