790 likes | 963 Views
Truth, Lies. And Off-grid Systems. A lberta S ustainable H ome. Jorg Ostrowski. EVS early days!. Leaders of Tomorrow Youth Conference. Off the Grid. What does “Off-grid” mean?. Self reliant Not connected to municipal water supply, sewer, natural gas or electrical power grid
E N D
Truth, Lies And Off-grid Systems
What does “Off-grid” mean? • Self reliant • Not connected to municipal water supply, sewer, natural gas or electrical power grid • In our climate, most sites still require a fossil fuel generator for winter backup
Off-grid Advantages • No monthly bills • More reliable than the grid • Sense of security in isolated areas • Lower emissions and fuel costs than generator “prime power”
Off-grid Disadvantages • Maintenance: battery levels and equalization, generator maintenance • Education: understanding of system highly recommended • Responsibility for any repairs • Higher emissions than BC grid during the winter months
Emmissions Comparison with Grid Power in the Kootenays • BC daytime production 86% hydroelectric • BC nighttime 100% coal and gas plant generated power (from Alberta) at 33-50% efficiency plus 7% transmission losses • Gasoline generator 25% efficient, diesel 40% • Battery charging/conversion efficiency 65%
Off-grid System Basics • No big resistive loads such as electric hot water tanks, stoves, dryers, hot tubs • 24VDC minimum system voltage recommended • Efficient LED or CFL lighting • Energy star rated appliances • Have a backup for your backup
Site Selection • Find a beautiful spot • A clear unobstructed view of the southern sky from the end of February until the end of October is sufficient • Peak charging hours are from 10am-4pm • Gravity water source with 70’ of head pressure an asset • Try to view your property through all seasons prior to building if possible
Microhydro Requirements • Head in ft x flow in gpm = output in W x 10 • 1500W or more could be a good candidate for a direct AC system • 250W or more will run an off-grid home using a DC generator coupled to a battery bank
Generators “Both the bane and the beginning of the off-grid system”
Gasoline Generators • Suitable for small to medium systems • “inverter” type units are the quietest, most fuel efficient and produce the cleanest power • Usually possible to connect an external fuel tank. • Can be sensitive to cold weather without some kind of “cold climate technology” ***
Diesel Generators • More efficient and longer life than gasoline generators • Good for large systems • Longer maintenance intervals • Difficult to cold start – generator shed with aux heat recommended or a Combined Heat and Power system • Possible to obtain bio-fuel
Propane Generators • Avoids the use of a second fuel if propane is already onsite • Increases propane use significantly • Can be problematic in general … • NG units designed as suburban backup units are NOT suitable for off-grid applications
Battery Selection Guide • Flooded “motive power” batteries best value • AGM (sealed) for remote applications • 2V “building blocks”
Function of the Inverter/Charger • Converts stored energy to household power • Charges batteries from a backup generator • Manages the operation of the backup generator • Monitors quality of produced and incoming power
Solar The best thing ever
Solar Module Selection • reputable manufacturer • 5 year material and workmanship warranty • 25 year 80% performance warranty • 60 cell “grid tie” 220 – 250W module currently best price point • Strong frame • Best quality currently are ON FIT compliant modules
Mounting Options • Roof mount • Ground mount • Solar tracker
To Track or Not to Track? • Solar trackers can increase summer yields by up to 35% but make little difference in the winter • Add roughly 35% to array cost • Introduce potential reliability issues • They are often cost effective on larger grid tie applications or where space is the limiting factor
Locating True South for Cranbrook • Solar noon method: position of the sun in the sky at 12:55 MST (13:55 during DST) • Compass method: make correction for declination of 15 deg W from magnetic S • Google Earth method: check the orientation of your home or landmark on your property
Solar-Friendly Roof Design • Orient building due south • Ideal fixed angle for our latitude 50 deg from horizontal • Consider snow loading • Consider eventual replacement of roof • Install wire during construction • Roof mounting can reduce costs • Partial shading detrimental to production
Pros Independent of home orientation/design Easier to change angle seasonally Easier to remove snow Cons Less elevation for shade avoidance More costly Potentially longer wire run More prone to theft/vandalism Ground Mounting
Power Shed vs Mech Room • Power shed can house array, backup generator and power system • Power shed can be built ahead of home to provide power for construction
Home Design Philosophy A: Build a standard new home with all the trimmings but in the bush Home Design Philosophy B: Build a “cabin in the woods” with the benefits of select modern conveniences
Heating System Considerations • Forced air furnaces, wood boilers and hydronic systems all use significant amounts of power to distribute heat • Minimize heating requirements of home by super-insulating • Adopt passive heating mechanisms • Investigate non electric options
Should you Install an Off-grid System Yourself? Maybe … or Maybe Not!
DIY Advice • Do your homework and read all manuals • Buy local or from a dealer who has technical knowledge of the equipment • Beware of “plug and play” claims • Locate generator away from home!
Notes on Buying a Used System • Prices have come down in recent years, especially on solar • Quality inverters (Trace, Xantrex, Outback, Magnum, Schneider) are very long lasting • Golf cart batteries last 7-10 years, high end 2V cells; 15-20 years • Solar 30+ years • Balance a good deal vs warranty