Off Grid Cost w/ Design Considerations

Off grid cost

 

Off grid cost is dependent on system requirements and expectations. The low cost of solar power is competitive with utility cost. However, solar is only produced during the day so energy storage is required for off grid systems. Energy storage is what makes off grid solar more expensive than utility power in urban areas. Off grid solar becomes cost effective when power poles are a half mile or more away.solar-icon

Understanding the difference between off grid solar and grid tied solar is important before requesting pricing for an off grid solar.

  • Off grid solar: This is what the average consumer thinks of when they see solar. The customer is completely independent from the electric companies and owns their own power. Off grid solar is a great power solution for energy demands in rural areas. Off grid power should be considered before paying an electric utility to set power poles.
  • Grid Tied Solar: is the most common system installed in areas with electric utilities available. The solar power first feeds the customers loads. Excessive power is then fed in to the grid where it powers neighboring loads.

Pricing requires an appropriate design. Designs typically require the following:

  • Load Chart: Every off grid load will need to be identified. If you are still in the pre-planning phase, then provide as much information as possible (Example: 1500 square foot house with gas appliances)
  • Peak Demand: Peak Demand is the total draw of power at any given second on your electrical system. Surge loads must also be accounted for in Peak Demand.
  • Daily Usage: Usage is the amount of energy being used. Occupancy and behavioral patterns are common factors.
  • Autonomy: This is the amount of days that the off grid system can provide power without it’s primary power source (solar). The battery bank will determine the autonomy of the off grid system. In typical system scenarios, solar power will feed loads and charge the battery bank during the day so that the battery bank can feed loads at night. But on cloudy days the solar power will not be available. Battery banks can provide power on cloudy days depending on their capacity. In a system with a 2 day autonomy, the battery bank can provide power for 2 days without the help of solar power. Systems often utilize generators to reduce the size of the battery bank while maintaining a comfortable autonomy.
  • Voltage: The following voltages are readily available 120v, 120/240v, 120/208v 3P.

How much does off grid solar cost?

It must first be understood that off grid systems can vary considerably. To better understand the cost, we will break down the cost into 3 categories: Solar Photovoltaic Installation, Off Grid Equipment, and Battery Bank.

Solar Photovoltaic Installation

Solar Modules

The solar module can vary in color, material, size, and origin. Black-framed modules are slightly more expensive than silver-framed modules. Polycrystalline and Monocrystalline technology are available and differ in looks more than production and cost. The main factor in solar module price is dependent on who makes the module. Where is the module made? How long has the company been in business? Is the module UL listed? These are all question that should be asked.

The origin of the module should be recognized by the consumer before they approve a contract. American made modules cost about 25% more than Chinese modules. It is often argued that American modules are of higher quality and manufactured under more ethical business practices.

Special attention should be paid to the brand of the module and who will be supplying the warranty. Solar companies have gone out of business in the USA and overseas, so choosing a well-known brand is a safe bet when relying on the 25 year production warranty.

Solar modules should be listed as UL1703 and solar inverters should be listed as UL1741.

SOLAR MODULE LOCATIONS

The placement of the solar array can be the leading difference in how much the solar installation costs.

ROOF-MOUNT

Roof-mounted solar is the most common application in the USA and usually the lowest prices are achieved by placing solar on the roof of a building. However, the cost is dependent on roof conditions:

  • Slope – Low slopes are easy to work on and reduce the cost in labor. Slopes more than 35 degrees typically cost more as the increase in steepness.
  • Material – Asphalt shingles and standing seam metal roofs are easiest to work on usually represent the generic price when looking at average solar rates. Tile, wood shake, and other materials can increase the price of installation because extra considerations must be taken and less common material may be requested. Note: In some areas, installers may be used to installing on a certain type of material and this can decrease the price of installation.

GROUND-MOUNTED

Ground-mounted solar is a great method of attachment when roof attachment isn’t an option. There are many options for ground mount framing systems and the price can vary depending on a few factors:

  • Soil-conditions – The price can vary depending on the work-ability of the soil in your location. Concrete foundations are used in most cases. Ground rings are also used if the soil conditions allow for this application.
  • Distance from interconnection point. Trenching and increased price of wire can increase the price of the solar installation.

SOLAR STRUCTURES

Custom designed solar structures usually cost more than the average cost of installation. The additional cost can sometimes be factored into the savings from using solar as a building function (ex. carport, pergola, canopy).

The cost of solar photovoltaic installation in off grid systems often vary from $2.00 – $4.00/watt depending on the location and method of application.

Off grid Equipment

The equipment used in off grid systems can vary in price and efficiency depending on the type of system.