One of the first considerations when you explore going off the grid is how much electricity do you need to generate. Regardless of whether you are exploring solar, wind, water or any combination thereof you don’t have to generate what you don’t use. New technology has significantly reduced the power usage of many common appliances.
Many off-gridders consider central heat and air to be incompatible with most energy generation devices. Conventional split hvac units use 25+ amps of current and surge to 50 amps or more during start up. If you are using solar and/or battery backup this will typically exceed the capacity of the inverter.
Conventional hvac units are an all or nothing proposition. A single thermostat turns the unit off or on based on the temperature in that immediate area and runs until that area reaches the desired temperature regardless of the temperature elsewhere in the home.
Newer inverter based air conditioning units utilize a low speed startup that eliminates surge. They also vary the speed of the compressor to match the load needed to heat or cool the dwelling. They can serve several rooms via one larger unit or mini-split units that serve an individual indoor unit in each room allowing temperatures to be set to the comfort level desired for that room. This allows a south facing room to get more cooling than a north facing room and unused rooms can be turned off.
Still, if you live in a high heat, high humidity area in the south or southwest air conditioning requires a substantial amount of energy. I live in Texas and need about fifty solar panels at two hundred and fifty watts each and one inverter that produces thirty five amps at two hundred forty volts to operate just hvac. An investment of about fifteen thousand dollars just for air conditioning. Of course copious mounts of insulation in six inch walls can mitigate that.
You’ll notice I’m discussing ovens separately from cook-tops. Simply put, technology has not reached the oven yet. They still rely on a radiant heat source and as such are energy hogs. Convection ovens do heat more quickly than conventional but use an electric motor to do so. Some of what can be done in an oven can be achieved in a microwave but chocolate chip cookies are not part of that capability. Get the smallest oven you can and use it sparingly. If we have a big cooking day planned i.e. Thanksgiving I start up the generator and we plan it all for a 3-4 hour period.
Your Grandma’s electric stove with the curly elements was about 74% efficient, a radiant is about 77% while induction is about 84%. One of the easiest ways to maximize your cook-tops efficiency is to match the pan size to the burner. Putting a small pan on a large burner drops it to as little as 44%. Another advantage of induction is instant on instant off. The heat is generated in the pan by a magnetic coil, not in the coil. This makes it safer and easier to clean.
If you still have the old tube type TV you know they create a lot of heat and heat is energy. Typically they use about 400-700 watts depending on size. I have a 42″ plasma and it uses about 240 watts and our main TV is a 55″ LED that uses 135 watts. You can improve slightly that by adjusting the brightness lower if it’s in a darkened room.
Computers, Tablets and Cell Phones
Unless you have a compelling need such as video or photo editing you may want to forego a desktop computer. Ours is commercial grade, has multiple monitors and multiple hard drives. For those that understand these things I have two SSD boot drives in a Raid 0 configuration for speed and three 10K RPM drives in a Raid 5 configuration for data integrity (I had a drive fail on me once and I lost everything). This comes at a price of about 275 watts when it is in use. To mitigate that I liberally use sleep modes when not in use. I also use a newer Speed-Step CPU that only goes as fast as necessary.
My recommendation for the average use is a laptop, at most (75-100 watts), or a tablet (30-40 watts) if all you do is e-mail and net surfing. I also have an older smart phone (10-20 watts) that is no longer active on a voice network but it works fine on wi-fi and I use it as a camera, calculator, mp3 player, quick e-mails and lite duty web surfing.
Everyone is aware of LED lighting so I don’t need to sing their praises highly but I would like to recap so you know the numbers. The old fashioned 60 watt light bulb used just that, 60 watts. Compact fluorescent’s use about 12 watts to give you the same amount of light and an LED will use about 9 watts. What many don’t know is that the bulb color plays a key role. The warm white color we are used to in our homes will use 9 watts in an LED while a daylight or bright white will use as little as 6 watts.