Off Grid Kits

Off Grid Solar System Info

The term off-grid refers to not being connected to an elctricity grid. There are many different reasons to have an off grid electrical system. Off grid systems can be used in areas where it is not economically feasible to run power lines, in places where it is impossible to run power lines, or in places where the owner simply does not want to be connected to the grid. It can be any kind of electricity generation, but we will be focused on solar electricity generation.

An Off Grid solar system consists of: solar panels, charge controllers, batteries, inverters, combiner boxes, breakers, surge protection, cabling, grounding equipment, and racking.

A solar panel is a set of solar photovoltaic modules electrically connected and usually mounted in an aluminum frame. A photovoltaic module is a packaged, connected assembly of individual solar cells. The solar panel can be used as a component of a larger photovoltaic system to generate and supply electricity in commercial and residential applications. Each module is rated by its DC output power under standard test conditions (STC), and can ranges from 5 to 400 watts. The efficiency of a module determines the area of a module given the same rated output - an 8% efficient 230 watt module will have twice the area of a 16% efficient 230 watt module. A single solar panel can produce only a limited amount of power; most installations contain multiple panels.

A charge controller may be used to power DC equipment with solar panels. The charge controller provides a regulated DC output and stores excess energy in a battery and also monitors battery voltage to prevent under or over charging. There are typically two types of charge controllers, PWM and MPPT. PWM (pulse width modulated) charge controllers are mainly designed to regulate voltage in situations that the open circuit voltage of the panels are matched with the controller, such as 12 volt panels with 12 volt controllers and 24 volt panels with 24 volt controllers, and so on. MPPT (maximum power point tracking) charge controllers are designed to take a higher open circuit voltage panel and regulate the voltage to safely charge a lower voltage battery bank, such as a 44.5 volt panel using an MPPT controller to safely charge a 12 volt battery bank. Generally, PWM charge controllers are much cheaper than MPPT's, but their limitations rule them out as a choice for many larger systems.

The Battery Bank is one of the most important components of an off grid solar sytem. All excess energy that is not consumed from the panels is stored here.

Historically, installers have favored using low- and medium-capacity 6 V or 12 V batteries wired in series and parallel to form a larger battery bank. This is often easier and less expensive upfront than using higher-capacity industrial batteries. Low- and medium-capacity batteries are often available off the shelf and locally in stock, which eliminates the shipping costs that the higher-capacity models incur. In addition, these lower-capacity models usually weigh 100 pounds or less and feature durable cases with handles that make them very easy for one or two people to move.

There are different types of batteries - gel, lead acid, lithium ion, etc.. The choice of batteries is usually dictated by personal preference, space constraints, or budget.

A solar inverter converts the direct current (DC) output of a solar panel into alternating current (AC) that can be fed into a commercial electrical grid or used by a local, off-grid electrical network. It is a critical component in a photovoltaic system, allowing the use of ordinary appliances. Solar inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking and anti-islanding protection.