DIY Solar Power System Offers Easy Emergency Power Supply


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How can I build a small solar power system for backup power during emergencies? 

Putting together a system that provides enough solar power to run a few key appliances during a power outage is certainly possible — and it’s also a fun and educational project.

Small backup solar power systems consist of a photovoltaic (PV) panel or two to generate the electricity, a battery to store the energy, a charge controller to keep the PV panel from overcharging the battery, and an inverter that converts the battery voltage into regular 120-volt alternating-current (AC) house power. All of these parts are easy to find, and connecting them is simple and safe as long as you follow the instructions. (You can also tap into easy, DIY solar-powered lighting — read more at Easy DIY Solar Lighting.)

Many variations of DIY solar power systems are possible, but the table below will give you a starting point. The equipment brands I chose are just examples. The batteries in these systems are oversized to allow for poor sun conditions, and you should only drain the batteries to their minimum capacity if you are confident that power will be restored promptly. Some off-grid folks who are careful about power consumption live year-round on systems no larger than the “Larger system” outlined below.

One good way to find a set of components is to search online for RV or cabin PV systems. Many suppliers sell kits of compatible components in various sizes.

You should keep the system’s batteries fully charged at all times, both to keep the batteries healthy and to have as much stored power as possible at the start of an outage. You can also find packaged systems that come assembled and wired except for the battery, which you can buy locally. This saves you the job of putting the system together yourself, but the price can be quite steep. And be careful — these systems are often advertised by the size of the inverter they use. Knowing the size of the PV panel and battery is much more important, as these determine what you can power and for how long, so be sure to look at the actual size of the PV panel and battery storage that any system supports.

1/6/2014 7:24:47 PM

How can I design a system to power a 220 volt water well?

Perry Fletcher
3/29/2013 9:07:39 PM

insulate the battery compartment to keep out moisture,cold but ventilate for battery offgases.

Virginia Gardner
3/29/2013 2:59:22 PM

I purchased a Sunforce system which is four 15 volt panels. I connected it to three connected 12 V deepcycle batteries. We built a cart out of marine ply, with storage under the panels for the batteries, and I can wheel it where I want it to be. Will winter weather (25-45 F) affect the batteries inside the compartment?

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