With an off grid solar system, you'll have true energy independence, but you won't have the grid to fall back on. 100% of your electrical needs are going to have to be met by your solar panels and batteries, so you need to size your system properly.
But before you size anything, you'll want to reduce your electrical needs as much as possible. Swap out all your incandescent light bulbs for LED bulbs. Consider replacing older appliances with newer, high efficiency appliances. Use non-electric appliances if you can. Isn't this extra work and expense? Yes, but if you can shave a few hundred Watt-hours off your daily use, you'll save big on solar panels and batteries because fewer will be needed to support your electrical needs.
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Whether on or off the grid, using solar panels (also called solar modules, PV modules, or PV panels) is one of the simplest and cleanest ways to convert the sun's energy into electricity. Solar panels are clean, quiet, direct, and incredibly durable, with a maintenance-free lifespan of decades. And solar has declined in price by more than half in just the last 10 years.
Real Goods' legacy is directly linked to the practicality and reliability of off-grid solar panels - we sold the first off-grid solar panel in the U.S., after all. But we've also built solar PV systems for thousands of customers across the country since 1978, and most are still going strong decades later.
Deep cycle batteries provide the consistency needed for comfortable off-grid living. They are the center of every off-grid solar (or wind or hydroelectric) system. Most renewable energy sources produce electricity instantaneously - but intermittently. The sun sets, the wind stops, the stream dries up - so you need batteries to store what went unused of that instantaneous power so you'll have it for later.
Everything comes and goes from the battery bank, so your solar batteries will be working hard. You can help protect your deep cycle batteries by regulating their charge with a charge controller and overcurrent protection and keeping tabs on them with a system monitor, but they do wear out over time. Real Goods has built renewable energy systems since 1978 using all kinds of batteries, and today we carry what we consider the industry's best for deep-cycling, off-grid use.
Every battery-based renewable energy system requires charge control. A charge controller brings your batteries to optimum charge level by monitoring voltage and limiting battery current as appropriate. For solar arrays over 200 Watts, an MPPT charge controller is almost always more economical when the power system is considered as a whole.
With wind or hydro power sources, an additional PWM type controller is often used in addition to the MPPT. The MPPT (Maximum Power Point Tracking) operates the solar array at its best possible performance, while a PWM can be configured to divert excess power to a diversion load – water and air heating elements.
Temperature compensation is important – voltage requirements for batteries are different at different temperatures. To prevent overcharging in the summer and undercharging in the winter, use temperature compensation probes whenever possible, and if not available, adjust the charge controller's charge voltage setpoints appropriately.
Whether in an emergency situation or during some off-grid fun like camping or road tripping, access to at least some electricity is as close to a necessity as you can get without being a biological requirement. Keeping a cell phone, GPS, or radio, or flashlight alive can easily be the difference between life and death - or the difference between a great backpacking trip and an endurance test.
To keep those gadgets charged, you need some portable power. We offer portable charging via solar, USB, 12-volt DC (think car cigarette lighter), and rechargeable household batteries. Solar is typically the most versatile option since it requires no extra equipment to provide the charge, but whenever possible, it’s a good idea to carry another portable power option as well.
No! Unlike grid-tie solar systems, off-grid systems are (as the name suggests) completely independent of the electrical grid and are therefore not affected by grid outages.
Yes. A deep cycle battery bank is the heart of an off-grid PV system. Everything comes and goes from the batteries and your power needs will be completely reliant on what your batteries have stored up whenever your solar panels (or wind/hydro turbines) aren't producing.
Batteries are a bit like muscles - they need some exercise to stay healthy, but not so much that they get worn out at an early age.
We've found it's best to aim for 3-5 days' worth of storage capacity if using lead acid batteries. Fewer than three days and your batteries will be cycling too deeply too frequently. More than five days and your battery bank starts getting more expensive than a backup generator or secondary charging source.
If you live in a reliably sunny place and use LFP (or LiFePO4) batteries instead of lead acid, you can probably safely get away with 2-3 days' worth of storage since LFP batteries handle true deep cycling much better than lead acid.
Our Solar Techs have answers! Contact them at 800-919-2400 or [email protected]
Deciding to get off the grid can be intimidating, but our Solar Living Sourcebook is the perfect primer for it - chock-full of exactly the kind of advice and considerations you should have to make an informed decision about it.