•Screwdriver, flat bladed for medium slotted screws
•Wrench, box end or open end, 7/16", two required •Wrench, box end or open end, 9/16", two required


Mounting structures are usually made of angle steel or aluminum rails and feet with stainless steel hardware. There are many sizes of mounting structures; from single module size up to 16 or more modules. All roof and ground mounting structures are designed for mounting on a flat surface and are adjustable to various tilt angles, usually 45 to 60 degrees from horizontal. In addition, you may choose to mount your modules on a pole mount. This will allow your modules to be higher, keeping them out of harm's way, and possibly exposing them to more sun. You may also choose to mount your array on a tracker, increasing the amount of power that your modules will produce each day.


Mounting structures should face true south (true north in the southern hemisphere) and be located where nothing will shade the solar modules between 9:00 AM and 4:00 PM. Be sure to correct for local variation in compass readings.


A secure foundation should be provided for the four legs of each mounting structure. When using concrete as a foundation material, four bolts should be inserted in the wet concrete with 1" of threads exposed to attach mounting feet. Mounting bolt locations can be determined from the mounting rack installation instructions.


Lay modules face down on a flat surface side by side with all of the junction boxes at the same end.

Place the two side rails along the ends of the modules so that they line up with the outer edges of the modules.

Using four 10-24 x 1/2" machine screws, nuts and lock washers for each module, attach each module to the rails, and hand tighten.

After hand tightening, make sure the assembly is squared and tighten with a screwdriver and 7/16" wrench.


Attach optional array combiner box to the side rail closest to the module junction boxes.


Attach interconnects between modules as indicated in the specific instructions for the voltage of your particular system. See the next section for detailed wiring instructions.


Attach one mounting foot to the lower end of each rail with a 1/4-20 x 1" bolt, nut, and washer. Hand tighten only. Attach one foot to each of the rear foundation bolts. Attach one leg to the top of each side rail using the hole in the side rail for the desired tilt angle.


Place modules face up across foundation using nuts, flat washers, and lock washer. Lift top of rack into position and attach base of each leg to rear mounting foot with a 1/4-20 x 1" bolt, lock washer, and nut. Tighten All Hardware.


Most photovoltaic modules have one or two junction boxes on the back to facilitate wiring. A single junction box usually contains two positive terminals, two negative terminals, and other terminals that are not electrically connected to the module but are useful in making series interconnections in 24 and 48 volt systems. Dual junction boxes each contain positive or negative terminals. A bypass diode should be installed whenever three or more modules are connected in series, such as in 36 volt plus systems. Figure 1 shows the connections inside a junction box.




The following diagrams show wiring details for series and parallel connections of two and four modules. According to the National Electric Code, rather than actually wiring module to module, wires should run from each module (or set of modules in 24 and 48 volt systems) to a combiner box. This is the method that we recommend as well.











The following diagrams show series/parallel wiring to get a 24 volt set from 12 volt modules. See Techno Tip: How to make a quick 24 volt connection with one piece of #10-2 wire


















Safe battery installation requires care to prevent damage and personal injury. Batteries are generally filled with a sulfuric acid electrolyte which can burn skin and eyes, and damage clothing, concrete and almost anything else it contacts. Keep batteries upright. In case of contact with electrolyte, flush with plain water for 15 minutes. Batteries are supplied in a nearly charged condition, and they are capable of supplying hundreds of amps through anything that conducts electricity between their positive and negative terminals and between intercell jumpers. In other words use great care when tightening bolts on battery interconnects, so that wrenches do not contact more than one terminal. In the event of a short circuit between terminals, the tool, battery terminal or battery may be destroyed. Batteries are wired in series to increase voltage. Batteries are wired in parallel to increase the amperage. (See series and connections in the glossary) Common wiring combinations are shown in the following diagrams:






The easiest way to determine the "footprint" of the battery bank is to start with all series connections. Line up the number of batteries that it will take to get the desired voltage, so that the "longer" sides touch each other. Connect them in series. This is a set. To connect the rest of the batteries, place the next set directly against the first so that all of the "short" sides touch all of the first set's "short" sides. Repeat for each set. Wire the sets together in parallel. Battery interconnecting cables should be tightened to approximately 10 foot-pounds with a box end wrench. Once all connections are made, battery terminals should be coated with a corrosion preventive or petroleum grease, such as Quick-Cote. The positive connection to the battery should go directly to a fuse with an amp rating no larger than the maximum ampacity of the smallest wire between the battery and any other fuse panel or circuit breakers. A battery can deliver thousands of amps into a short circuit, causing even very large gauge wires to burn. The table on the back cover lists the maximum current recommended for various sizes and lengths of wire.



The installation of a solar electric system starts with decisions about the location of each component. All aspects considered, it is a fairly complex proposition but when done correctly will provide years of trouble free service.

The physical location of each piece of equipment can greatly affect the operation of the system. First, consider that batteries need to be vented to the outside and be kept away from the living space but they also need to be protected from freezing. Furthermore, the NEC requires a fire wall around the batteries. This can be common sheet rock.

Second, the batteries, power center and inverter are grouped together, usually within five feet of each other. A common place for this equipment is in the utility room or garage. This can be a good choice as long as there is an exterior wall for battery ventilation. In colder climates this option offers the advantage of keeping the batteries a bit warmer.

Another option for equipment placement is a shed separate from the house. It could be a larger shed that is also used for other purposes or it could be just big enough to hold the power equipment alone. The "power house" can be quite a distance from the home if all loads are AC. If there are DC loads in the house the distance is more limited.

If you have yet to build your home the power house idea has a unique advantage. You can build the shed first, then install the equipment in it. This allows you to use the sun as a solar generator to run power tools for your construction projects.

The location of PV modules is even more crucial. Many people assume that solar modules should be installed on the roof of the house. Sometimes that may be the best place but often it is not. Consider that if your roofing material is already a few years old you may face the job of moving the modules before re-roofing.

Shade trees are great at keeping the house cool but even one tree will greatly reduce the output of the solar array. If cutting those trees would be unthinkable, consider putting the array out in the sunny part of the yard. If your house has no roof area facing south the modules will be awkward to mount so again consider moving them to a pole mount. The extra distance may mean higher wire cost but that will often pay for itself by providing more power.