Off Grid Solar Cabins
Off Grid Homes
Off Grid Solar
Off Grid Solar Cottages
Off Grid living
Stand Alone Solar Systems
PV Panels, Led Lighting, Solar Domestic Heating, Solar Heating, Solar On Demand Water,
Inverters and Batteries
Off-Grid Solar-Electric Systems
Although they are most common in remote locations without utility grid service, off-grid solar-electric systems can work anywhere. These systems operate independently from the grid to provide all of a household’s electricity. That means no electric bills and no blackouts—at least none caused by grid failures. People choose to live off-grid for a variety of reasons, including the prohibitive cost of bringing utility lines to remote homesites, the appeal of an independent lifestyle, or the general reliability a solar-electric system provides. Those who choose to live off-grid often need to make adjustments to when and how they use electricity, so they can live within the limitations of the system’s design. This doesn’t necessarily imply doing without, but rather is a shift to a more conscientious use of electricity.
Off Grid living
Stand Alone Solar Systems with Generator backup
If you would like a free design contact us with a description of your project firstname.lastname@example.org
Checkout $897 Sale Price
Let us do a free design analysis for your cottage
To do a solar design and financial analysis of your home or building
If you would like a free design contact us with a description of your project email@example.com
WSE has been involved with several off grid applications like the one below on a remote island in northern Saskatchewan.
Each application is a bit different but the concepts are much the same
WSE is also partnered with Vereco Net Zero Homes and would be happy to design and build your your next net zero off grid cottage or cabin
Below is some examples of a cabin on a remote island in Northern Saskatchewan
This particular design was for summer usage only
The cabin is about 150 feet from shore and about 50 feet above the water.
The first pump is placed as close to the water as possible. A 12 volt deep cycle battery is positioned near the pump. The battery to connected to the main battery source with 12 gauge wire. An on/off switch is required to turn off when not requiring water.
The battery is connected is connected to the solar panels using 12 gauge wire to trickle charge the battery. In some cases a small 20 watt PV panel could be used to charge the batter instead of stringing the 12 volt wire.
The second pump is at the cabin supplying the cold water supply and the WSE47-20 solar hot water heater. The pump is connected to the main battery supply thru an on/off switch.
The WSE47-20 incorporates a float valve which turns off the water supply when the 140 liter tank is full.
The WSE47 -20 supplies the hot water for your hot water needs
The third pump supplies the hot water to the cabin.
25 Watt 12 volt Thin Film Panels
WSE can do free analysis to determine your PV and battery requirements
Please check the WSE Polysun analysis of a cabin in La Ronge Saskatchewan using 2,000 watts a day
Ensures battery doesn't overcharge from Solar panels
Includes battery gauge
Charge current and wattage
The Aluminum Strip Light is a 12VDC unit and is available in both warm white and cool white, as well as 50cm and 100cm lengths.
Off-Grid System Sizing
Be Energy Conservative
Cooking, Heating and Cooling
|Living off the grid is a romantic ambition for some, a practical necessity for others. But whatever your motivation for off-grid living, cutting the electrical umbilical cord from the utility shouldn't be taken lightly.
Before you pull out the calculator, size up the realities and challenges of living off the grid. Then, once you're stand-alone system.
Designing a stand-alone PV system differs substantially from designing a batteryless grid-direct system. Instead of meeting the home's annual demand, a stand-alone system must be able to meet energy requirements every day of the year. The PV system must be able to keep the battery bank charged-or include a generator for backup-because once the last amp-hour is drawn, the lights go out (see "Backup Generators" sidebar).
Efficiency first! This long-standing mantra for PV system design still holds true and is especially important for offgrid
systems. Every $1 spent using energy efficiently is estimated to save between $3 and $5 on PV system costs. As a system designer, it's virtually impossible to mandate wise energy use by the end user, but we can specify efficient appliances, such as Energy Star refrigerators and clothes washers, and strategies, such as shifting loads to non-electric sources during times of low solar insolation. For more on efficiency and load-shifting.
Energy Consumption and the Solar Resource. Carefully comparing the home's daily and seasonal energy usage
with the daily and seasonal availability of the sun will help prevent energy production shortages. This important
step involves a careful analysis of the home's changing seasonal load profile and the corresponding solar resource
throughout the year. Paramount to this analysis is the presence or absence of a backup charging source, such as a
generator. If a backup charging source is not incorporated, the designer should choose as the design target the time of year when energy consumption is expected to be highest and the solar resource at its lowest-usually during the
depths of winter.
Without a backup generator, a PV system must produce every watt-hour required, at all times of the year. This is
often a tall task during the winter months and typically results in a costly system that is oversized for the rest of the
year. For this reason, stand-alone systems without a backup charging source are often limited to smaller, nonresidence applications, such as seasonal cabins.
For systems with a backup charging source, more design flexibility means designers can use average consumption
numbers and peak sun-hour values. For example, they can choose to size the system at a time of year when
energy consumption is not at its highest or lowest, but in the middle-say, a typical day in the fall or spring. In
addition, they might use the specific location's average solar resource. Using the average for both consumption and
sun-hours will strike a good balance between an affordable array size and generator run time. If minimal generator run time is desired, the array and battery bank may need to be upsized based on more conservative consumption and sun-hour values. a prerequisite to energy design and production.
Size it Up: A Case Study
Who: The Ackerman-Leist family
Where: Pawlet, Vermont, approximately 3/4 mile from
Solar window: 8 a.m. to 4 p.m.
Average daily solar resource: 4.6 peak sun-hours*
System backup: 4 kW backup engine generator
System voltage: 24 VDC
Projected energy use (AC and DC): 2.2 kWh per day
Expected avg. ambient temperature for batteries: 60°F
Record low temperature: -35°F
Desired days of autonomy: 3
Desired battery depth of discharge: 50%
Battery: 6 V nominal, 225 Ah, deep-cycle flooded lead-acid
PV modules: 12 V nominal, 80 W STC , array tilt equal to the
Charge controller: MPPT, 60 A
Array mounting: Pole-mount
*Peak sun-hours are based on Concord, New Hampshire,
values, which more accurately reflect the site's latitude and
Step 1: Estimate Electric Load
Determine the amount of energy (kWh or Wh) that will be consumed on a daily basis. If it is for a home not yet built, thiscan be a very involved and time-consuming step. A designer will need to work closely with the homeowner/builder to realistically estimate the daily and seasonal energy requirements.
The power (W) of individual loads and their estimated energy consumption (Wh) can be tallied to calculate the
household's average daily load. This step will help identify opportunities for efficiency improvements and pave the wayfor sizing the system components. The table below lists the electrical loads found in the Ackerman-Leist household. The family heats their home with wood, cooks with wood and propane, uses a propane refrigerator, and heats their water with a solar thermal system and a backup propane boiler, so
those are not factors in the load analysis.
According to the table, daily household loads average 1.8 AC kWh and 0.36 DC kWh (from the chest freezer), totaling almost 2.2 kWh a day.
Battery Bank Sizing
The average daily load is then used to calculate the battery requirements. The batteries must be able to store the total daily load, in addition to the extra energy lost by inverting from direct current (DC) to alternating current (AC). Dividing the AC average daily load by the inverter efficiency (90% standard), inflates the average daily load that the batteries must store to account for efficiency losses from the inverter.
While inverter manufacturers will commonly list "peak efficiency" (generally ranging from about 92% to 95%), we
use a more conservative 90% to account for the fact that the actual operating efficiency depends on the AC load, which is constantly fluctuating. Hence, an inverter will rarely operate at the load level which results in peak efficiency.
The battery bank's ambient operating temperature is also taken into consideration, since temperature affects a flooded lead-acid battery's internal resistance and ability to hold acharge. As temperatures fall below 80°F, battery capacity is reduced. A battery temperature multiplier table can be used-check with the battery manufacturer for their specific correction factors.
Days of autonomy is also an important design criterion, as it dictates how many days the battery bank will need
to sustain the average daily load when there is little or no sunshine to recharge it. It's a compromise between having
energy during overcast spells, how much time the generator will run, and the added cost of a larger battery bank. The more days of autonomy desired, the larger the battery bank.
Generally three to five days of autonomy provides a good balance. Keep in mind that the larger the battery bank, the larger the PV array will need to be to recharge the bank sufficiently on a regular basis-or the more the generator will be needed to pick up the slack.
The last major design criterion for sizing batteries is the depth of discharge (DOD). While deep-cycle lead-acid
batteries are designed to discharge 80% of their capacity, the deeper they are discharged on a regular basis, the
fewer charge/discharge cycles they can provide over their lifetime. When choosing a DOD, strike a balance between longevity, cost, and the significant hassle of replacement.
Many system designers will specify a 50% DOD to be used in the worksheet. Because several days of autonomy areaccounted for, which increases the battery bank size, the actual depth of discharge during sunny weather will often be less than 20%. The DOD design value can greatly affect the cost of the battery bank. (For simplicity, the numbers from the load table have been rounded in the following equations.)
(1,800 AC Wh Avg. Daily Load ÷ 0.9 Inv. Eff.) + 360 DC Wh Avg. Daily Load = 2,360 Wh/day
2,360 Wh/day ÷ 24 DC System Volts = 98.3 654.7 ÷ 225 Ah individual battery capacity = 3 parallel
battery strings (rounded up from 2.9)
24 V system voltage ÷ 6 V battery voltage = 4 batteries in
3 parallel strings x 4 batteries in series = 12 total batteries
The battery calculations indicate that a battery bank made up of 12 of the chosen 6 V, 225 Ah, flooded leadacid
batteries will provide adequate storage to meet daily energy requirements, inverter efficiency losses, operating
temperature effects, days of autonomy, and the desired average depth of discharge. The number of batteries or series strings of batteries connected in parallel should be kept to a minimum, preferably three or less. This minimizes the chance of unequal charging from one battery or string to the next.
While using higher-capacity batteries would have resulted in fewer parallel strings, the Ackerman-Leists chose lowe rcapacity batteries for budgetary reasons.Avg. Ah per day 98.3 x 1.11 battery temperature multiplier x 3 days
autonomy ÷ 0.5 DOD = 654.7 total system Ah
Batteries are rated by their capacity in amp-hours and at the rate that they are charged/discharged. In most PV systems, the appropriate Ah rating to use is based on a discharge over 20 hours. Unlike shallow-cycle vehicle batteries, deep-cycle batteries in PV systems are charged and discharged over 24 hours, and the weather, level of solar irradiance, and energy usage patterns all influence the charge/discharge scheme.
In this system example, the battery could provide 225 Ah of stored energy-if discharged 100% over 20 hours. If it were discharged faster, the capacity would be less, and vice versa. Be sure to check with the battery manufacturer, as they provide battery-specific Ah capacity values based on different charge/discharge rates. Choose the 20-hour rate when sizing and selecting batteries, unless a specific load profile dictates otherwise.
Solar Panel Array Sizing
Dividing the Wh required by the location's peak sun-hours leaves us with the initial PV array watts needed. For this sizing example, the solar data for Concord, New Hampshire (at 43.2°N) provides the closest estimate of the solar resource for Pawlet, Vermont (at 43.3°N) at an array tilt angle equal to latitude. Since this system is using a backup generator, the average daily peak sun-hours can be used (4.6), as the generator can cover energy shortages during periods of low insolation or high energy consumption-or both. If less generator run time is desired, the array size must be increased or daily energy consumption must be reduced appropriately (or both).