Just like car manufacturers come out with a "design only" car that is meant not to drive but for conceptualization and to push the engineering team, I wanted to see how many incandescent light bulbs it would take to actually heat a home... in case that your heater goes out in the middle of winter and you find yourself with nothing but 500 illegal light bulbs and way too many power strips. 

Incandescent bulbs light bulbs only convert 10% of their energy use towards putting out actual light, the other 90% is wasted and converted to heat.  So let's say that a 60 watt light bulb puts out 54 watts of heat to a room per hour (60 x 90%). Here is a chart on how many kWh of heat is produced from different quantities of light bulbs

So to compare, a furnace produces 75,000 BTU of energy per hr for a mid-size home or roughly 22 kWh of energy. That means we would only need about 500 light bulbs to produce the same amount of heat as our furnace is supplying! At $1.50 per 60 watt bulb, it would cost an initial investment of $750 for 500 light bulbs. When we hooked up all our power cords in a fire safe manner and plugged in our lamps, 500 light bulbs would draw 30 kWh, which is 8 kWh MORE than our 75,000 BTU furnace.  Plus our furnace would last about 20 years longer than our bulbs. BUT if you are in a jam and have no heat, now you know how many bulbs you need to keep warm at night! 

It can seem like you can't go wrong with solar hot water heaters. Electric hot water heaters are the second biggest energy user in a home, always keeping the water hot and ready for your use... Did you catch that? Electric water heaters... not gas water heaters, your gas water heater is typically the largest gas appliance in a home if you have natural gas service. The thing is that in Arizona, our natural gas cost is relatively cheap compared to propane or even other cities like Chicago. Plus our winter climate does not demand a lot of natural gas usage from our furnaces... It simply does not get that cold during the winter in Phoenix.

You may get free hot water from a solar water heater but solar water heaters always have an electric water heater backup tank that WILL kick on if the water temperature doesn't reach it's 140 degree set point, which is happens more frequently than your rep may be aware of.  We have received lots of feedback from homeowners who had a solar hot water systems added to their existing gas water heater where their electric bills actually went up! 

By adding another water heater that is electric powered, your electricity use will unfortunately go up. It's an important distinction your solar hot water company rep may be blind to or may not disclose to you.

Solar hot water heaters use the sun to heat the water used for doing dishes, showers, laundry and in bathrooms and they are ideal for all electric homes with 3 or more occupants.  Solar tax credits and rebates make solar affordable for everyone but it may not be suitable for everyone.  Installing solar water heaters to homes may seem like a great idea but if your home uses natural gas for water heating, the old saying, "the grass is always greener on the other side" can apply to your water heater.  Do yourself a favor and stick with your existing gas water heater and put the money towards insulating your walls or sealing your ductwork instead.

If you are looking to upgrade your existing gas water heater, look into a tankless water heater instead. For larger families, a 20 gallon storage tank is available for reserve water.  Tankless water heaters are super efficient, only turning on when you turn on the hot water and instantly heating your water.