When thinking about our place in society, I know a few folks who would like nothing else but to go “off the grid”-and most days, this is I as well. When one makes the leap they are confronted by the true essence of what is an actual “need” in their lives. Lifestyle plays a major part in this and without commenting on the morality of anything here, let’s jump straight to true “need” – one of which is electricity. There is a wide array of appropriate technologies for going off grid that come to mind. These include solar, wind, hydro, tidal, biogas, and geo thermal just to name a few. For the sake of this article we will look at photovoltaic electricity and it’s use as an off grid application.
For starters lets get some terminology down. The term grid tied refers to an energy system that is connected to the utility grid. These systems do not rely on battery storage. Off grid refers to energy systems that are independent from the utility grid and these systems rely on storage of some kind. With both types of systems the primary principle is the same. Light strikes a solar module and produces electrical current but where that current goes and how it is utilized is the major difference between the two types of systems.
Off grid solar electric systems are often more complex and in most cases more expensive than their grid tied counterparts. Also, they must be designed to meet 100% of the electrical demand because there is not a utility grid to pick up the slack. Off grid systems rely on storage of the energy produced so it is available at night and during times of less than adequate sunlight. These systems are sometimes referred to as battery based systems due to the fact that storage batteries are the key piece of equipment all the other components interact with.
Solar modules are just component of equipment that makes up an off grid energy system. Charge controllers, inverters, battery banks, system monitors and an assortment of breakers, fuses and disconnects are required.
The solar energy generated from the solar modules is sent through the charge controller and right into the battery bank. When a load such as a light or appliance is turned on, electrical current from the battery bank is drawn through the inverter to the breaker panel, which then distributes energy to whichever circuit demands it. The breaker panel in an off grid home receives its power from batteries through the inverter. Because batteries are the key to off grid systems, proper maintenance of the battery bank is essential. Protection from weathering elements is a must. Also, when installing a battery bank ensuring an equal charge and discharge, encourages years of battery life.
With off the grid systems sizing is extremely important and great care must be taken to ensure that the system adequately meets the applications energy demands. Unlike the infinite amount of power available to a traditional home connected to the utility grid, an off grid home’s amount of power is limited by the size of the battery bank, the size of the solar array and the energy conservation of its occupants. Because of this, energy efficiency is of utmost importance. Regardless of the type of energy you choose to implement, the most important step one should make when going off the grid is to minimize their energy usage. For every dollar spent on efficiency, the average homeowner is saving 3 to 5 times that amount off the cost of their renewable energy system. Efficiency really does make a huge impact.
Off grid systems are primarily used in remote areas when bringing in electrical lines is too expensive or impossible. These systems are also popular in developing countries where the utility grid is unreliable or non-existent. Off grid systems require care and attention to the little things, which is all part and parcel of the off grid life itself. Off grid PV allows for greater flexibility for those that require electricity in locations where “needs” are those you suffice yourself.
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