Remote (Off-grid) Solar/Wind Systems

How They Work

Remote solar & wind systems provide AC & DC power where the electrical grid is not available. Solar panels or wind turbines charge batteries, the batteries store DC power and provide power for DC & AC loads. If 120VAC/240VAC is required a DC-AC inverter is required, inverters take DC power and convert it to usable AC power.

System Components

Solar Panels
Charge Controllers
Wind Turbines
Batteries
Inverters
System Sizing

On-grid

Solar panels convert energy from the sun to DC power for charging batteries. Solar panels come in a wide range of sizes, voltages, and wattage. Solar panels need to be located in direct sunlight with no shading facing dew south mounted at an angle between 45 and 60 degrees. There are many different mounting options, roof mounts (flush or tilted), pole mounts, and ground mounts.

A charge controller is a device that is used to regulate the charging of batteries. There are two different types of charge controllers, MPPT (Maximum Power Point Tracking) and conventional charge controllers. In ideal conditions you will gain up to %30 off your solar array by using a MPPT charge controller. This is possible because MPPT controllers continually calculate the solar panel maximum power voltage. The MPPT controller operates the solar panel at its maximum power voltage to extract the maximum power. The higher power extracted from the solar panel is provided to the battery in the form of increased charge current. Conventional controllers cannot increase the power because they connect the solar panel directly to the battery when the battery is discharged and don't calculate the solar panel maximum power voltage.

Wind turbines convert the potential energy in the wind to DC power for charging batteries. When the wind blows the blades stop a percentage of the wind, the larger the turbine the more power it will produce. Wind turbines can be a great battery charging source if they are located in the proper area with good wind conditions. A good guideline is a minimum 12mph average wind speed and the 20/250 rule, 20 feet above any surrounding object within a 250 foot radius. Using this guideline will allow a wind turbine to perform very well.

Batteries in remote solar/wind systems are used to store the energy from the sun or wind. The energy in batteries is measured in amp hours, amp hours refer to how many amps can be used from the battery over a period of time. There are three battery types used in remote solar systems, deep cycle flooded, Gel, and AGM. The most common battery used in a remote system is deep cycle flooded because of cost and durability.

Inverters also come in different models for different system needs. Some inverters are very simple, DC terminals on one end and AC plugs on the other end for plugging in something simple like a toaster. Common inverters for larger remote systems are hard wired, these inverters are designed to be wired into AC distribution panels and also have built in battery chargers that require power from a generator. A generator can be used for providing power for the battery charger when there is not enough sun or wind and for running large loads like power tools that will drain the batteries fast.

To size a system a couple things are needed. Will solar or wind work best for the system, how often will the system be used, and how many watts will be used daily. When Clear Power Solutions design a system the first thing we do is determine the battery/batteries capacity. We design the battery/batteries to be discharged %50, this extends the life of the battery and depending on the customers needs we will size the battery to provide power for 3 days with no sun/wind. When sizing the solar/wind Clear Power design the solar/wind around the customers needs. Some customers will require recharging faster the others. For example one customer might only use the system on the weekends, this way the batteries have all week to recharge. One thing to remember is no two systems are the same, every system is designed around the customers needs.