Off-Grid Homes

Solar Power for Off-Grid Living: A Comprehensive Guide

Choosing an off-grid solar power system can be a viable alternative to utility power, especially for new construction homes where grid connection is costly or impractical, and for homeowners and occupants who value self-sufficiency.

Designing, planning, and budgeting for a fully off-grid energy system requires significantly more planning than adding backup power to a conventional grid-tied home. Existing grid-connected homes can also achieve similar energy autonomy with a backup system.

This guide will provide you with the essential knowledge to help you navigate the requirements of off-grid living. You'll be better equipped to decide if this self-sustaining lifestyle aligns with your home-building goals and values.

Quick Facts:

• "Off-grid" means permanently off-grid (as opposed to backup for a grid-connected home).

• Planning must be done ahead of construction for the best results.

• Smaller, super-insulated homes achieve the best results.

• Off-grid living is not suitable for all lifestyles.

What Off-Grid Living Really Means

Living off-grid is about more than eliminating monthly energy bills. It represents a commitment to self-sufficiency, requiring you to understand energy management and system operation, and to take a hands-on approach to maintaining your power supply. It demands a shift in how you think about and use energy on a daily basis.

Our Approach to Off-Grid Projects

We take a comprehensive approach to qualifying off-grid solar projects and ensuring that reliable, long-term satisfaction is achievable. We help determine whether it is right for you; otherwise, we may recommend a grid power connection. Ultimately, favorability depends on the location, building characteristics, and overall energy needs.

Challenges to Consider

Off-grid living isn't for everyone. Discussing this decision with your household is essential, as it will affect everyone's day-to-day life. Battery charge can run low, and backup generators might fail—sometimes at critical moments—leaving you with a temporary power outage. Larger system sizes, careful energy-level monitoring, and periodic generator maintenance are keys to success.

When off-grid is appropriate:

• Locations where a grid connection is unviable.

• New construction of an energy-efficient home.

• Households that value independence and are committed to understanding and managing their energy supply.

When off-grid is not appropriate:

• For households that want limitless energy (no interest in hands-on energy management).

• If power outages are highly consequential.

• No interest in independence or self-sufficiency (dependency).

• Rentals or part-time residences.

• Merely to avoid the cost of a grid connection or save money.

BH Solar is committed to ensuring satisfaction by qualifying each project and educating our clients as to the pros and cons of their specific situation.

Key points to consider:

• Consult with us prior to beginning an off-grid project, finalizing the home design, or starting construction. We may or may not recommend or accept your project.

  
  

• A permanent internet connection is required for monitoring and troubleshooting. Starlink is the preferred option for remote locations.

  
  

• Space heating must be propane or biomass (e.g., wood), not electric.

• Your move-in date should be in the spring or summer, not in the winter.

  
  

• Homeowners/occupants must commit to learning about and managing energy use and to monitoring the battery state of charge daily. This is especially important during the winter or whenever sunshine is limited. You will be responsible for avoiding energy shortages, testing and maintaining the backup generator, and recovering from power outages.

  
  

• Ground-mounted solar panels require a location within 300 feet of the home that receives full sun exposure for >90% of the day in the winter. Forested areas, north-facing slopes, and locations shadowed by terrain may not be suitable.

  
  

• Ground-mounted solar arrays are strongly preferred over roof-mounted arrays so that snow can be easily removed. Exceptions may include detached structures such as garages with high-sloped roofs oriented directly south.

  
  

• The battery power system must be installed in a non-habitable indoor space, such as a mechanical/utility room or garage. The solar inverter and battery require about six feet of lateral wall clearance (typical), and the temperature must be maintained between 50 and 80 degrees.
  

• For supplementary/backup power, we will install a whole-home generator (typically 14kW to 26kW), such as the Kohler 14RCA. The propane tank and connections will be installed by others. We also recommend owning a 240V portable generator as an additional backup option.

  
  

• We highly recommend installing multiple heat sources. Air-to-air heat pumps are recommended as they are an efficient option for most heating and cooling needs, but during extreme cold, an additional heat source, such as a forced-air propane furnace and/or a wood/pellet stove, is necessary. Electric (resistive) space-heating options like baseboard, cove, and other resistive-element heaters are not advisable, as they will quickly drain the battery. Heat pumps equipped with auxiliary resistive heating elements may be used, though we will configure the heating element to be powered only by the backup generator.

  
  

• Water lines must not depend on power (e.g., heat tape) for freeze prevention. Water lines must not be installed in exterior walls or uninsulated crawl spaces.
  

• The home's battery system will not be installed or activated until construction is nearing completion and internet access is available. This is necessary to avoid any complications or liability. Building contractors must supply their own generators.
  

• We do not sell or service wind turbines. In most cases, small wind turbines are not a practical power source compared to solar panels, so we do not recommend them.
  

• We provide orientation and guidance and answer technical questions as you become accustomed to your new power system. We also advise reviewing the user manuals to become fully acquainted with the system's functions. For some technical issues, you may need to contact the inverter manufacturer directly.

  
  

• Please be aware that we cannot guarantee emergency response service to remote locations, especially during the winter. Our acceptance of your project and installation does not make us liable for any incidental inconvenience or damage resulting from a power outage or system fault.

Building Efficient, Sustainable Homes

A well-insulated and tightly sealed home greatly reduces the need for heating and cooling, which is especially important in colder climates since space heating is the largest energy expenditure. Energy efficiency of the building envelope leads to a more reliable and cost-effective power system, reduced reliance on backup generators, and an overall more dependable setup that will cost less in the long run.

Key elements for an energy-efficient home include:

• High insulation levels (R-40 for walls, R-60 for ceilings, plus under-slab and footing insulation),

• A tightly sealed building envelope, verified by blower-door tests,

• Energy-recovery ventilation (ERV) systems to maintain fresh air and manage humidity.

Depending on use and occupancy, a home built around these principles may consume as little as one-third the energy of an average home. Investing in energy-efficient construction and appliances enhances reliability and comfort and reduces maintenance costs over the home's lifetime.

Heating an Off-Grid Home

When designing an off-grid residence, it is crucial to consider the energy requirements for heating in the winter, as this is usually when the peak energy demand coincides with the lowest solar energy availability. We recommend installing two or more heat sources other than electric resistive heat (i.e., baseboard or cove heaters).

Air-to-air heat pumps are an excellent choice for heating during milder winter weather. A propane furnace or wood stove becomes necessary when the weather is especially cold.

Consult with an expert HVAC contractor to choose the best heating options for your building design. These options will vary depending on factors such as the building size and layout, exposure to sun and wind, and ducting and ventilation options.

How the power system works

An off-grid solar power system uses photovoltaic (PV) solar panels to transform sunlight into electricity, which is then stored in a battery. The solar panels supply power directly to the home while simultaneously replenishing the battery during daylight hours. The energy stored in the battery can be accessed for use whenever needed.

During increased power consumption and reduced sunlight (typically in winter), a backup generator kicks in to recharge the battery before it depletes.

A smart breaker panel can also be employed to enhance features such as usage monitoring and individual circuit controls via a mobile device.

System Sizing

Several factors need to be considered when sizing an off-grid solar system for a new home. These include the size of the home, the number of occupants, the quality of construction, the types of major appliances used, and individual energy consumption habits. The energy requirements during winter, specifically in December and January, serve as the baseline for determining system size. Ideally, the solar power system should be designed to meet at least 90% of the energy needs during the winter to minimize reliance on backup generators.

Winter months typically have the highest energy demands, with an average South Dakota home consuming around 12,000 kWh per year or approximately 30-40 kWh per day. However, energy consumption varies depending on the specific characteristics of each building and its residents.

The inverter's power capacity must be sufficient to handle peak electrical loads in off-grid homes. While an average home requires at least 8 kW peak power capacity, installing a 12 or 15 kW inverter for off-grid setups is recommended to ensure reliable operation with high-power appliances and well pumps.

A battery capacity of 30 to 40 kWh is generally sufficient for a typical household. Furthermore, the battery capacity should increase proportionally as more solar panels are added.

The solar array capacity typically ranges from 12 kW to 18 kW, equivalent to 20 to 40 solar panels, to ensure sufficient energy generation to recharge the battery throughout the year.

To learn more about kilowatts and kilowatt-hours, see our Power vs Energy post.

Appliances

Certain appliances, such as ovens and clothes dryers, require significant power and energy even when used only occasionally. On the other hand, appliances like refrigerators and dishwashers consume less power but are frequently operated. The major consumers deserve special attention for optimizing efficiency when selecting your appliances. LED lighting and 120-volt plug-in devices that are seldom used do not account for a significant portion of energy consumption.

Here are some important appliance and utility-related tips to consider:

Ventilation:

• A blower-door test, performed during the rough-in phase of construction, is recommended to assess the building's airtightness and address leaks.

• Mechanical ventilation is essential for high-efficiency homes with a tight building envelope. This includes energy-recovery ventilators (ERVs) that exchange indoor air with filtered outdoor air with minimal heat gain/loss.

• Whole-house fans (large exhaust fans) can be a good alternative to an active mechanical ventilation system, but the air is not filtered, and temperature/humidity is not recovered or controlled.

Heating, Ventilation, and Air-Conditioning (HVAC):

• Air-conditioning works well with solar power because cooling is needed most when the sun is shining.

• Air-sourced heat pumps are efficient for cooling and can be installed as part of a central-air ducted system/furnace or wall mount.

• Mini-split heat pumps are good for cooling individual rooms.

• High-efficiency central air conditioners are acceptable, but avoid oversizing.

• Ground-sourced heat pumps can be goo,d but expensive and sometimes inefficient. They should be used only when carefully planned, with expert guidance, and in the right locations.

• Electric (resistive or radiant) heat can be an auxiliary heating option for individual rooms, but its power demand for whole-home heating would be excessive and, therefore, not advisable.

Water:

• A large tank is preferred for water heating, and propane heat is usually favored. If electric, the heating elements may be downsized (to 3800W elements), and a daytime timer may be installed for optimization.

• An on-demand propane water heater is also a good choice; these can be used to supplement an electric tank as well.

• Do not install an on-demand electric water heater, as the required electrical power is too high.

• Well pumps require a high-power start and therefore need to be fitted with a soft-start capacitor (for smaller pumps) or a VFD controller (for larger pumps) to run efficiently and avoid overloading the battery system.

• For even greater resiliency, the well pump can fill a cistern for surface water storage during the day, and a small pressure pump (or gravity) can provide water pressure on demand with minimal power at any time.

Kitchen:

• Induction cooktops are the most energy-efficient option for cooking, but a standard electric range is acceptable as well. If using propane, ensure proper ventilation.

• Most modern refrigerators and freezers are energy-efficient and do not require special consideration. However, ice-makers use a significant amount of energy and can be avoided.

• Dishwashers are relatively efficient and represent a small share of energy use. They can even be more energy-efficient than hand washing, especially when using efficiency settings.

Laundry:

• Newer clothes washers are very energy-efficient. A high-extraction (fast-spinning) washer is recommended to reduce energy use for drying.

• Propane/Gas vented dryers are a good choice that requires little electricity. They are affordable, readily available, and easy to maintain.

• Electric, vented (hot-air, resistive electric-heating element) clothes dryers are highly energy-intensive, inefficient, and potentially damaging to fabrics. However, they are the most affordable and widely used. If used, a lower-powered option (under 5 kW) is preferable. Smaller dryers are not more energy-efficient, but they demand less power in exchange for a longer drying cycle, helping to avoid system overloads.

• A condenser dryer (typically called "ventless" or "unvented") is like a vented dryer, except that the extracted moisture is collected in a tank that must be emptied. These use slightly more power than a vented dryer, but dry clothes faster. Their efficiency is not significantly different from that of a vented dryer.

• Heat pump dryers are considered more energy-efficient than other types of electric dryers. This is because they use a heat pump to recycle heat from the dryer's air, rather than generating new heat via an electric heating element. This allows them to use less energy overall and can result in significant energy savings over time. Additionally, heat pump dryers tend to run at lower temperatures, which can be gentler on clothes and may help to preserve their color and shape. However, heat pump dryers tend to be more expensive than other types of electric dryers, and they may take longer to dry clothes.

Electronics:

• Most electronics consume power even when not in use. To reduce this, you can use power strips or smart switches to turn off power to home entertainment systems and gaming consoles when not in use.

• Reliable internet connectivity is crucial for monitoring and updating solar and battery power systems. Avoid rented modems/routers from internet service providers, as they may be outdated and inefficient. Satellite-based internet modems tend to use much more power than regular modems/routers; however, Starlink is a favorable, low-energy satellite system for locations where broadband is not accessible.

When it comes to appliances, investing in high-efficiency options can lead to long-term cost savings and greater satisfaction.

Thank you for taking the time to read through this guide! Having gained a better understanding of off-grid solar systems, you are now equipped to make well-informed decisions when planning your project. Don't hesitate to reach out to us at Black Hills Solar with any inquiries.