Home Solar Power Basics: Part II
In Part I of Modern Enviro’s Home Solar Power Guide, we looked at the three basic types of systems available to homeowners. In this section, we’ll explore some of the specific features and technologies needed for a home solar energy system.
Not All Solar Panels Are Created Equal
Take a look at solar panels currently available on the market, and you’ll frequently see a couple terms that make a big difference in price and power-producing ability.
Amorphous silicon solar panels are relatively inexpensive to manufacture, although they are not the most efficient ones available. One advantage is that they can be constructed using just a thin coating of the energy-absorbing silicon material, resulting in a thin and lightweight solar panel.
Crystalline silicon solar panels (most commonly using Polycrystalline silicon) are more expensive to manufacture, but they are also more efficient than amorphous silicon – meaning more power can be produced from a panel with the same size surface area.
Both types of panels will get the job done – so the choice will usually come down to a homeowner’s budget and the amount of available space for positioning a solar array.
Where Does The Power Go?
Systems that send power directly into a home’s existing electrical grid connection are the most straightforward, because they simply add more electricity into the existing infrastructure. But for off-the-grid applications like a vacation cabin, or a home that needs backup power independent of its grid connection, there are a few other essential components for the system.
Deep Cycle Batteries
In an off-the-grid setup, power from solar panels feeds into an array of batteries. And not just any batteries will do: since a home solar energy system will require many charge/discharge cycles over its lifespan, and since the amount of electricity flowing into and out of the batteries is extremely variable, specialized batteries known as deep cycle batteries are a must. WindSun.com features an excellent fact sheet about the features to look for in a solar battery system.
Similar to a tank that collects rainwater, batteries that collect electricity from solar panels will “overflow” if they aren’t regulated, causing serious damage. The voltage from a panel can vary wildly too depending on the strength of the sunlight, so it needs to be regulated to match the voltage of the battery that will store the charge.
The solution is a charge controller that adjusts the voltage of the current and functions like a shutoff valve, sensing when the batteries have reached their full capacity. A charge controller can also prevent batteries from discharging too far, since completely exhausting their charge can cause damage.
Since the electricity that flows from a solar panel is DC power (direct current), an inverter is needed to convert it to alternating current (AC) power so it can be used in a home. Even grid-integrated systems require an inverter so the current from the solar array is compatible with the current that comes from the utility company.
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For more information about the different types of solar panels available, check out Part III of our Home Solar Power Guide.