Draft a power budget to determine how much power your household needs, then use these tips for conserving energy on an off-grid solar power system.
We get quite a few inquiries about setting up off-grid power systems. Now, designing a home power system isn’t rocket science but it is time consuming. The first thing a person needs to do is figure up the amount of power that they need.
How Much Power Does Your Household Need?
If you’re on grid power the easiest (and quickest) way is to look at your electric bill. Each month the power company bills you for the power that you use. Not having purchased electricity from the power company for a good many years I have no idea what the power consumption is for the average home so I did some research. That yielded conflicting data depending upon the sources cited but the most reliable figures put it around 1,000 kWh per month. Keep in mind that this is an average and does not reflect regional differences. For example, those in the South use a lot more electricity (on average) than those in the north, (probably because there are few non-electric alternatives to cooling a house and many non-electric ways to heat one!). This puts the daily total around 32 kWh (kilo-watt-hours equal 1000 watts per hour). That’s 32,000 watts per day. That sounds like a lot (and it is), but keep in mind that the average air-conditioner uses 3,500 watts per hour (3.5 kWh).
What this means is that if you’re thinking about converting to solar power you’ll need to produce, on average, 32,000 watts of electricity per day to power your home.
Solar panels produce their maximum output in direct sunlight. Unless you have a sun tracking system that means you’re going to get between five and six hours per day of maximum power from your solar panels. Your solar panels will need to generate 32,000 watts of electricity in that six hour time span which translates into 5,3333 watts per hour. Add another twenty-percent due to losses in the system and the total generating capacity required jumps to 6,400 watts. That’s thirty-two, 200 watt panels. The best price I found on a quick internet search yielded a $7,000.00 price tag for those 32 panels. (That, incidentally, is a very good deal.)
Remember, that’s for the solar panels only! It doesn’t include mounting hardware, wiring, charge controllers, batteries, inverters, legal permits or the cost of installation. It’s very easy to spend $25,000.00 or more on an off-grid power system for the average household.
Planning for Peak Usage
Now, that’s the estimate for average energy use. Off-grid systems must be able to handle the power needs during peak use and when solar power is at a minimum. In our case we have long days of consistent summer sunshine but in the winter we have very short, often cloudy days. We need power in the winter to run lights, laptops, television/VCR (we do most of our writing and watching movies during the winter season) and other electrical devices in the mornings and evenings at the time of year when we have the least amount of sun available. Our system is sized to provide the power we need in the winter so in the summer our battery bank is often fully charged by 10:00 AM.
When you plan for peak use or reduced outputs your initial investment often doubles or triples so that $25,000 system now cost upwards of fifty to seventy-five thousand dollars.
It is at this point (while the sticker shock takes hold!) that I learn how serious they are about living life off the grid. People have a tendency to waste plentiful resources. Grid power is virtually unlimited for most people so conserving electricity it isn’t something many seriously pursue. In other words, the majority of households could greatly reduce their energy consumption if they put their mind to it.
Conduct an Energy Inventory
The best way that I’m aware of to reduce energy consumption is to begin by conducting an energy inventory. So … once they’ve recovered from the initial estimate for going off the grid, I recommend that they go through their home and write down the watt ratings on every electrical device in their homes and provide an estimate of how many hours it’s used. Since these numbers are located on the back or bottom of most appliances this is going to take some effort.
Next, take a sheet of paper and divide it into five columns. At the top of the first column write in “name” which means the name of the appliance. On the second write “watts” which is the amount of power used by the appliance. (Note: some will have the number of “amps” instead of watt rating. Multiply the amps and volts to arrive at the number of watts an appliance uses.) On the next column write, “hours used.” In this column estimate the number of hours the unit in question is used per day. If it’s only used three days a week then total the hours for those three days and divide that number by seven to get the number of hours it’s used per day. In the fourth column, record the “daily energy use” in watts, (multiply the number of watts by the hours used.) In the fifth column write “notes.” In this last column you can put down ways to cut the energy requirements of this appliance. This might include using the item less or purchasing an appliance that’s more energy efficient, etc.
For example, replacing four, sixty-watt, incandescent light bulbs with four LED lights that put out the same amount of light, may reduce your energy use from 240 watts to less than 30 watts (a ninety-percent reduction in energy use). That’s a “savings” of 210 watts. Think about that for a minute; that’s the potential output of one, 200 watt solar panel!
Check the power needs of your refrigerator, television, computer (and monitor), gaming systems (X-Box, Wii, etc.) water heater, hair dryers, washer, dryer, air conditioner and heating system, and everything else in your home that uses electricity. Be aware of “ghost loads.” Many appliances use power even when turned off. We use outlet strips and shut power off completely to our television, Blue-Ray, Wii and other appliances when they aren’t being used.
Keeping to an Energy Budget
Once you have an idea on where your electricity is being “spent” you can begin to work on an “energy budget.” Just like trimming a financial budget, you begin by cutting out frivolous expenditures and reducing use whenever possible. As big ticket items need replaced, replace them with energy efficient models.
When thinking about off-grid living I recommend that people use other energy sources like selling their electric range, water heater, dryer, etc. and purchasing replacements that use propane. But even then a person should make his goal conserving resources rather than just switching to a different energy source.
For example: We use less than 100 pounds of propane per year running our propane cook stove and that includes many hours of pressure canning. Some of the ways we accomplish this include putting only the amount of water we need in the teakettle before heating it up. There’s no sense spending four times the energy needed to heat a quart of water when you only need one cup. We shut off the pilot light to the top burners. We light the burners as needed using a long reach butane lighter like those used to light charcoal grills. When the lighter runs out of butane we can still light the burners using the spark at the tip. We’ve used the same lighter for over a year that way. We do a lot of cooking on the wood (heating) stove when it’s in use (which is a lot in our climate). We use a solar cooker as much as possible.
Note: You may not be able to use a solar cooker for every meal but if you can average one meal a day using it you’ve cut the energy used cooking by thirty-percent.
The clothes a person wears can reduce energy usage. For example: We wash all of our laundry by hand and it didn’t take long to realize that we could wash three pairs of shorts easier and in less water than one pair of blue jeans. Ankle high socks are easier to wash than full length socks. Sweaters are easier to wash than sweat shirts. Some types of fabric are easier to wash as well. What you accomplish is putting more changes of clothing in each load so you run the washer fewer times. You save water, electricity, detergent, drying times, and your appliances last longer.
Consider Passive Solar Energy
“Passive solar” energy used to be seen as a great way to tap into the sun’s power. The problem is that in most cases passive solar can’t handle all of our energy needs. For example, on cloudy days, passive solar water heaters don’t get the water temperature hot enough. But even if passive solar water heaters can’t raise the water temperature as high as your hot water heater they raise it some and every degree the water entering the hot water heater is increased is one degree less the hot water heater needs to heat it. The same holds true for passive solar heating. It may not keep your home toasty warm but if it raises the air temperature a few degrees it’s just that much less the home heating system has to work. Even skylights reduce the need for artificial lighting.
Be creative! Many passive solar heating devices can be built very cheaply and are virtually maintenance free. Take advantage of the free energy. If you’re building your own home or remodeling an existing one plan to make use of passive solar energy and/or ways to make your home less dependent upon air-conditioning in summer. We have a friend in Texas who carefully designed her home to be cool in summer. In an area where most homes depend on air-conditioners in the summer hers is cool and breezy without artificial aids.
Again, be creative!
We operate on the principle that many small changes can yield big results. My book, Creating the Low-Budget Homestead, has an entire chapter with more details on how to set up a low-budget, off-grid power system. It’s also loaded with other ideas that will save money in your daily life whether on or off the grid.
Note: While the focus on this series of posts will be on solar power and off-grid living, if you put these tips to use while on the grid you may be able to put enough back to take the plunge and break free of the power company altogether.
