The process of of how solar installers design a solar energy system is often a mystery for most consumers. Because of this, we would like to give you some insight into how solar installers design a solar power system for your home or business. A solar power system is designed considering two important factors – the amount of space that you have available for installing solar panels and the amount of electricity you consume annually. Other factors, like shading analysis and the efficiency of solar panels and inverters also come into play.
Space to Install Solar Panels
Assuming that you are interested in installing solar panels on the roof, the amount of viable roof space determines the maximum number of solar panels that can be installed. An individual solar panel varies in size, but is usually around 16 square feet in a rectangular shape. The panels are affixed to racking systems that are more efficiently designed when installed in a contiguous space together rather than spread out all over the roof. The available roof space – limited by vents, chimneys, dormers and any required offsets from roof edges or roof-mounted equipment – may limit the system size such that a solar system offsets less than 100% of your annual electricity consumption. The average solar system in the US consumes about 300-400 square feet of space, so your viable roof space may limit the size of the solar system you are able to install. In this case, installers may recommend higher efficiency panels that generate more electricity per square feet than standard panels. These will also come at a higher cost, but is something you might consider depending on your personal goals.
An average solar panel system may generate different amount of electricity based on your location in the world and the orientation of your roof, so installers will use various tools to estimate the viable solar system size. These tools allow installers to use aerial imagery and to “draw” in system designs on your roof space in order to estimate the size of a system that will fit and how much electricity this system will produce each year given a number of assumptions. If you’d like to try this yourself, you can go to PV Watts, a tool developed by the National Renewable Energy Laboratories, to estimate your system size and annual production.
Annual electricity consumption
One of the first information a solar installer might ask for is twelve months of electricity bills. While this might seem like a lot of information right off the bat, this gives the installer a sense for how much energy you use throughout the year. Often an electric bill will include the last twelve months of usage history in a table or a chart, removing the need to fish around for past bills. Armed with your electricity usage information, the installer can determine about how big of a solar photovoltaic system would be required to offset 100% of your annual usage. This will vary by your location and roof profile. Typically, solar panel systems are designed to cover 100% or less of annual usage to maximize the financial benefits, but if you are planning to increase your energy use in the near future – for example, if you are planning to buy an electric car or converting from oil to electric heat pumps – you might consult with your solar consultant to estimate your expected energy demand in order to design a system that better matches that use profile.
The impact of shading
If your roof has shading – from neighboring trees, other buildings or large chimneys – installers may choose to leave these areas uncovered by solar panels to optimize the production of the system or may place panels in these locations with the understanding that these panels may produce less energy at certain times of the day. Installers may also suggest changes to system design to create separate solar panel strings that are designed to avoid power loss from shading or may suggest the use of micro-inverters or power optimizers to help mitigate the impact of shading of the production of the overall system. The latter two technologies may come at a higher cost, but these costs may be justified from the additional power they help your system to generate.
The above factors are taken into account when designing a solar system for your home or business. The process of providing an initial system design can be quite quick and can often be turned around within a day or so. Other factors – such as the structural integrity of your roof, the condition of your existing electrical system or the specific impact of shading – may require that solar installers visit your property to gather additional information in order to develop a system design and a price quote that they can stand by. To get started, get an instant estimate of your solar potential at EnergySage and register to get quotes from a network of pre-screened solar installers.
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