Off Grid Cabin

Project Overview: Our client reached out to us while they were in the design stages of building an off grid cabin located on Storm Mountain. In the short term, the cabin will serve for weekend getaways. In the long term, they would like to spend weeks at the cabin. Their system consists of solar panels, micro-inverters, battery energy storage, and backup generator. The system has been designed to meet the demands of their longer stay durations.

We are incorporating the following high end system components in their design:

• Generac off grid generator. https://www.generac.com/all-products/generators/home-backup-generators/ecogen/15kw-7034-wifi-enabled

• SimpliPhi Power batteries.https://simpliphipower.com/product/access-phi-sol-ark/

• Sol-Ark 15k hybrid inverter: https://www.sol-ark.com/sol-ark-15k-all-in-one/

• Extreme weather rated solar panels. https://qcells.com/us/get-started/complete-energy-solution/solar-panel-detail?slrPnlId=SRPL220817160809064&look=001

The most important factor with this project, and any off grid project is to have enough reliable power from solar + batteries so that the generator runs as little as possible. Our load analysis, which accounts for variables including surge loads and low power factor loads determined that we needed 16 panels and 15kw of battery storage for 2 days autonomy when sunlight isn't available. Some clients like to have a longer duration of autonomy, but this site has a backup generator hard lined to a propane tank so our client was comfortable with 2 days autonomy.

Wind and snow loads at 9,200ft present very real design challenges. Many racking systems simply did not meet the rigid structural design requirements of 167mph wind gusts and 100psf snow loads. We ended up selected the MT Solar raised ground mount system. This design has two 6" schedule 80 steel poles set 3 feet in the ground, braced with rebar and over 50 cubit ft of concrete per pole. The angle of the panels can be adjusted in April and October, to provide maximum production. Here in the Greater Denver area, we are at 40 degrees lattitude. In April the panel tilt will be reduced to 25 degrees (40-15) to better capture the sun rays high in the sky. In October, the panel tilt will be adjusted to 55 degrees (40+15) to better capture the sun rays low in the sky. The panels will be raised so that the lowest edge of the panels sits 5' above grade. This design feature allows our client to arrive at their property Christmas week, and not have to plow snow to clear the area in front of their solar panels when they arrive.

This project was the culmination of electrical engineers, structural engineers, electricians and solar design specialists working together. We are proud of the end result.