We are going to explore in a two part series some of the common mistakes made in developing residential solar power systems. Going to wind or solar power is a decision than can be a very good investment. But a lot of people make some assumption and have misunderstandings of what these green power sources accomplish.

Off-Grid vs Grid-Tied Solar System Design

Very few solar systems that are installed are truly off-grid systems. For an off-grid system you are usually located where no grid power is available and excess power is stored in batteries. Batteries are very costly. This allows you to draw power when there is no sun. But majority of solar systems installed are grid-tie systems. Your system generates power and sell it back to the power company. You then draw power and use the credits for when there is no sun. The utility power goes down so does your solar. Reason is most inverters supply stepped sine wave power not continuous sine wave like the power grid.

Solar Power System Considerations

Just taking your last months bill and installing panels to cover the power is not enough. Some factors are:
• Solar Panel Efficiency: Panels have efficiency ratings. They also suffer 0.5-1% drop per year. That means when in 20 years your panels will have dropped by 20-20% and are less efficient. You should design in some ‘headroom’ to cover this drop in the efficiency of the panels.
• Solar Energy Climate: Sun belt areas have more sunshine per year on average than other locations. But daylight and sun hours are not the same. Out of a 12-hour summer day you are only getting about 7 ‘sun’ hours or the peak efficiency of the power producing time. Sun hours depend on panel orientation of the panels. Also panels are tested, indoors under climate controlled conditions, something never experienced by panels in an actual outdoor installation. High temperatures of summer and actually serve to decline the efficiency of the panels.
• Solar Panel Voltage: Inverters and charge controllers are designed with maximum and minimum voltage input windows. Panels and batteries are also designed within these parameters. Your system must be designed to produce voltage within these specs of the inverters and charge controllers. Temperature can change the voltage output. If panels don’t serve up the right voltage to your system in might not perform as well or even worse, you can damage your equipment.
• Solar Battery Bank Sizing: Off-grid systems with batteries need to have the battery bank with the charging source is a common issue. Your panel array needs to be enough to charge the system without over charging. Too much current can damage your batteries from overcharging the system. Some batteries have a ‘memory’ and running at partial or full drain can damage the batteries. Operating at or full charge regularly is better.

Solar Panels Work when the Power Goes Out

Not so! Grid-tied systems store the excess power on the public grid. When the grid goes down so does your solar/wind system. The only way to prevent this is to install an expensive battery system. Batteries are mandatory in an off-grid system installation.

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Call Advanced Electric Solutions Corp to learn more about taking advantage of solar and wind power in your home or business today.