When nonprofits begin to explore going solar, one of the first questions is “How big does our system have to be?”. The answer to that starts with knowing how much energy you use.

How do you know what your annual energy consumption is? Most of us are more familiar with the price we pay for energy than we are with the amount of power our organization uses. The price of commercial power can often vary depending on the time of day, your rate plan, and the time of year. Decision makers including the Executive Director, the Chief Financial Officer, and the board can become familiar with your org’s power consumption by looking at your collected power bills for a year and reading your kWh. Many power companies and utilities are also making Green Button Data available to help consumers and institutions understand their power usage at a more granular level.

Before you calculate the size of your system, you can increase your building’s energy efficiency to reduce your consumption. Start with converting to LED light bulbs from fluorescents (both tube fluorescents and those “curly cue” kind.) Don’t wait for your bulbs to burn out. LEDs have a brighter, cleaner light, a longer life span and use as little as 1/2 as much energy as CFLs and only 1/10 as much as an incandescent bulb! Other significant gains in efficiency can come from a maintenance tune-up of your HVAC system. Find more ways to cut down your consumption at’s strategies for buildings and plant

Once you have reduced your consumption, you can get an idea of what your new baseline energy usage is. Collect bills for the next few months and track your kWh. To estimate the size of your system, use this rule of thumb according to Center for Sustainable Energy “Divide your annual consumption (kWh) by 1,700 kWh/year (1 kW of solar will generate about 1,700 kWh/year). This will give you an approximate system size.

For example, the Center for Spiritual Living, San Jose project called for a 24 kW system that was designed to meet all of their energy needs.

Their annual power consumption was akin to: 40,800kWh / 1700 kWh per year = 24kW system.

One major benefit of partnering with CollectiveSun is that you don’t have to guess what size your system needs to be. Our operations manager, Matt Brennan and our installer partners will use their expertise to determine the right size and the right equipment for your location and power needs.

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