Going off the electrical grid can begin as an environmental or political ideal, but in practical terms, 2017 is the year to turn ideas into reality. For those brave pioneers who tried to free themselves from utility companies in years past, the available options today will seem like Utopia. While many details must be considered, your off-grid plan needs two major components: the photovoltaic (PV) panels and the storage batteries.
When deciding to make the leap to off-grid power, plan carefully. Calculate your power consumption needs, how many PV panels you will need to meet those needs and how many batteries (and of what type) you will require to store power for sunless days and overnight use. The first consideration is how long you expect batteries to sustain you and your family:
- Overnight and cloudy days?
- Through a snowstorm of three or four days?
A 24-volt battery bank could help you along through overnight or morning cloud cover, but if you are hoping to stretch batteries out to three or four days, you will need greater capacity.
You can find load calculators online. Take into account future growth in your family, so if now you have adorable toddlers, you can plan to have enough electricity to meet the needs of power-hungry teens.
The power consumption calculation guides you to battery selection. You have many choices in solar batteries these days, and prices are falling:
- Tesla Powerwall — using lithium-ion batteries for maximum efficiency
- Iron Edison — using nickel-iron batteries
- Adara — lithium-ion energy storage systems
Plan carefully, because batteries are still expensive, though environmentally far friendlier than using a gasoline-powered generator to keep the lights on when the sun is off duty.
Solar storage batteries work best when kept warm (80 ℉), so if you know you are going off-grid for your mountainside winter vacation home, expect to need more batteries than if you were planning an oceanfront installation for summers only.
PV panels can power your home’s entire ongoing needs and are the source for power storage sent to the backup batteries. In off-grid systems, the PV panels need to maximize energy collection, so you may find that rooftop panels are only a start. You may want to consider additional ground or pole mounts, or even panels that can rotate to capture as much sunlight through the day as possible.
Solar Charge Controller
Getting the power from the PV panels to the batteries requires a solar charge controller. The controller acts as a sort of one-way valve, preventing battery power from running out to the panels on cloudy days and keeping the batteries fully charged by the panels during sunny days.
A solar charge controller can either be a Maximum Power Point Tracking (MPPT) or Pulse Width Modulated (PWM) controller. The MPPT is superior, but more costly since it matches PV panel output to the battery bank’s capacity. A PWM controller is the more traditional, less expensive, solution.
Though called “solar batteries,” the technology behind power storage is not exclusive to solar energy. All batteries store and deliver power as Direct Current (DC), rather than the Alternating Current (AC) our everyday appliances, computers, and devices demand. This means the flow is not directly from batteries into your home; you need an inverter, or possibly even two.
North American electrical current is 240 volts that are stepped down to 120 volts; some appliances (a stove, a clothes dryer) may use 240-volt AC, while everything else in your home requires 120-volt power. While some inverters can be ganged to provide 240 volts, you may find a simpler solution by creating two separate power feeds from the batteries.
Before embarking on an exciting adventure in off-grid living, partner with seasoned solar professionals. Contact Golden Solar today to learn more about the many facets of off-grid solar power. You can avoid costly mistakes by tapping the knowledge and experience of the experts at Golden Solar.