Jon and Mary are installing an off-grid power system to complement their newly constructed cabin in the Idaho Panhandle. They built their new home using a diesel generator as power source, but wish to move away from fossil-fueled electricity. Building their system in manageable stages, they elected to put their electronic components in a remote "power station" that sits away from the house. This keeps the distance short from solar array to batteries, adding to system efficiency and saving money on copper wire. It also keeps the batteries and other components out of the living space, so there is no special construction required for solar power. The generator will be housed in a small annex on the back side of the building. As a bonus, the power station will also serve as a greenhouse, with an interior wall to divide the plant area from the power components. Jon is currently in the process of interior finish work, but has all of the components on site and ready for installation.
Jon plans to start solar electric production with a smaller array of 4 Sharp 180 watt modules that will mount on the South-facing wall above the sliding door, using General Specialties S-Rails. A larger array will be added next year on a General Specialties UPM post mount.
Conduits are already placed for the AC wire that will deliver electricity to his home. A second conduit runs to the location where the post mount will be installed. A third conduit was added for future expansion if another array becomes part of the plan. Always smart to think ahead...
Although Jon and Mary will be initially getting most of their power from their diesel generator, their Magnum Energy MS4024AE sinewave inverter will provide 105 amps charging power to store electricity in their battery bank. This means much higher overall fuel efficiency from the generator, and the convenience of having power available 24 hours a day. The Sharp solar panels will give a nice 720 watt boost to the system, as well as providing the lower-current charging needed to "top-off" the batteries on a daily basis. This will further reduce generator run-time and make a healthier daily charging profile for the batteries. This array will connect to a Blue Sky Solar Boost 50 charge controller. The Boost 50 is a genuine MPPT (maximum power point tracking) controller which can boost the array output by up to 30%. Altogether, a sound plan for getting started with solar power and keeping it within a reasonable budget.
Here we have the HUP SolarOne SO-6-85-23 deep-cycle battery set, in 24 volt configuration. Jon chose SolarOne batteries for their heavy-duty construction and 10-year warranty. This is a hefty, 1160 amp/hour battery bank that is well-matched to Jon and Mary's generator and inverter output capabilities, to stay within recommended charging rates. Jon will be building an enclosure for these batteries, and a vent fan will be connected to the Outback FM80 charge controller to exhaust battery gasses from the building.
The "big" array will be approximately 2500 watts, bringing the total solar input to more than 3200 watts. This will be enough for robust battery charging, nearly eliminating use of the generator during most of the year.
HUP_SolarOne batteries consist of 6, 2-volt cells arranged in a heavy steel container, so each container is a 12-volt battery. This makes it easy to configure for 12, 24, or 48 volt systems. Each battery ships complete with interconnecting bars to tie the cells together (not installed in the photo) and the required hardware. Cell caps are a hinged, "snap open" type for easy maintenance.
February, 2010: Here are a couple of photo updates sent by Jon. You can see that their small array has been installed on the face of the power station. The four, 180 watt Sharp solar panels are mounted to simple S-RAILS roof/wall mounts that can be adjusted for seasonal tilt. The winter season at this latitude makes a near-vertical adjustment appropriate.
Although 720 watts of solar array isn't enough for most households, Jon and Mary can rely on their diesel generator and Magnum inverter to do the lion's share of battery charging in the winter months. This array is large enough to keep their batteries at a healthy state-of-charge when they choose to be away from home for an extended period, supporting an energy-efficient refrigerator or freezer, for instance. Their longer-range plan is to add a 2500 watt array on a General Specialties pole mount during the summer of 2010. The conduit for this proposed array extends to the North, behind the building at a sufficient distance to be clear of long winter shadows. The Outback FM80 charge controller is pre-installed on their Midnite Solar power center, so installation of the new array can be completed quickly.
As of this date, the system has been operational for more than 2 months and has been trouble-free. Jon has been obsessively educating himself about his new power system... a very good plan for long-term success.
Check back here for more photos as this installation progresses...