Tiny is Huge!
Tiny Houses are a big success these days.
Cutting back your possessions to the bare minimum and fitting your new life into a tiny house has become a dream for many. With tiny houses generally comes tiny electric use. But how can you make your electric bill as small as possible?
Tiny Houses on Wheels (THOW) give you the added bonus of being able your life on the road. Where ever you are, you are already home. With this comes the question of how do I power this new found freedom?
Solar power is the answer to both of these questions.
Whether you are permanently attached to the electric grid, or travelling around with intermittent access to the grid, there are solutions available to add solar panels to your tiny house.
Grid-tied Tiny House
If your tiny house is in a permanent location that has access to the electric grid, and has a sunny spot available, grid-tied solar is the most affordable option for you. The solar panels can go on the roof, or if you prefer, out in the yard on a pole or ground mount. If you are already connected to the grid, figuring out how much solar you need is easy as can be. Simply look at your electric bill and see how many kWh (kilowatt hours) you buy from them.
Electricity Supply $0.08963 x 200kWh $17.93
In this example, the house is using 200kWh a month. From here, you have a few simple options. You can enter that 200kWh in a grid-tied calculator to see how much solar you need in your area.
In the picture to the left, we selected Cleveland, Ohio as the location. To make 100% of our energy, we would need about 2000W, or 2kW, of solar panels. If we used 300W panels, seven solar panels would provide all of the power we need. A grid-tied inverter would convert the DC power from the panels to AC power for your tiny house. You’d make solar electricity during the day, use what you need, and sell the rest back to the grid for your neighbors to use. Then at night, you simply buy the power back, same as usual. Your utility meter would spin backwards and forwards, depending on if you were selling or buying power. This is known as NetMetering. At the end of the month, you may have a credit to use in a less sunny month.
A very nice advantage of grid-tied solar is that you don’t have to make all of your power with solar. If you don’t have the space or budget for seven solar panels, no problem, just install as many as you can. You’ll make less electricity with solar and have to buy more from the grid. But that’s no big deal, you still will have all the energy you need.
Off-grid Tiny House
If your tiny house is on the move, or is in a remote location without access to the electric grid, or you just don’t want to depend on the grid for your power, an off-grid solar system is for you. With off-grid solar, you make all of your power during the day, and store it in batteries to use whenever you need it. If you are in an area that has a bad season for solar, like winter in Vermont, you will want to have a generator available to charge your batteries when needed.
Many off-grid solar systems can actually connect to the grid if it is available, and charge up the battery bank if solar isn’t enough. But the big difference is that you don’t sell extra power back to the grid, you store it. This can be convenient if you are staying at an RV park during a stretch of bad weather.
Sizing an off-grid solar system requires more due diligence than a grid-tied solar system. As we mentioned, if your grid-tied solar system is too small for all of your loads, you just buy what you need from the grid. With off-grid, you are on your own. If you didn’t make enough electricity during the day, you may have to postpone vacuuming your rug until the next sunny day.
Sizing an Off-grid Tiny House
So how big of a solar system do you need for your tiny house? That all depends on the loads. If you are cooling the house with a ceiling fan, it will need a heck of a lot smaller system than if you are using air conditioning. Likewise with heating with a wood stove versus an electric heater. It also depends on where you are. A system in the southwest will often generate twice as much energy annually than in the northeast.
If you aren’t already on the grid and able to check your energy use by looking at your power bill, the first step is to create a loads list. This will list out everything you’ll be powering; how many watts it draws and for how many hours a day.
Below is an example of some common household items, and how much energy they can use a day. Actual mileage may vary, so take some time to create a loads list using our online calculator to get an accurate number. That will get you your daily energy used. Multiply it by 30 to get your monthly use.
Ensuring that you use very efficient appliances will also help you minimize the size solar system you need. EnergyStar’s website can give you the annual use of rated appliances, divide by 12 to get monthly use.
|Device||Power in watts (W)||Hours On Each Day||Energy in watt hours (Wh)|
|LED lights||6W||4 hours||24 Wh|
|Incandescent light||60W||4 hours||240 Wh
(Note that this used ten times the energy as the LED light. It is worth every penny to replace your incandescent lights with LED lights if you want to power it with solar)
|Cell Phone||5W||3 hours||15Wh|
|2 hours charging
6 hours running
|Internet router||6W||12 hours (turn off when not accessing the internet)||72Wh|
|Full size fridge||83W||24 hours (actually on half the time)||1000 Wh (1 kWh)|
|Ultra energy efficient fridge||180W surge||24 hours (off most of the time)||168 Wh|
|Space heater|| Low/ Medium/ High
|8 hours at Medium||8000 Wh (8kWh)|
|Solar booster pump (for water pressure)||100W||½ hour||50Wh|
|Well pump – 1HP||750W||1 hour||750Wh|
|Blender – Powerful (Ninja)||1500W||5 minutes||125Wh|
|Blender – Conventional||500W||5 minutes||41Wh|
|Window air conditioner||500W to 1500W (depending on size)||8 hours||8000Wh (averaging)|
The most accurate way to know how much energy your appliances are using is to actually measure the use with a Kill A Watt meter. It measures the Wh used over a period of time, giving you precisely the information yo need to properly size your solar system.
Example Off-grid Sizing
Let’s go back to that house in Columbus, OH. We’ve now decided to take it off-grid. If I use the 1800W Tiny House Kit, I can potentially generate 81kWh a month with it. That’s 2,700Wh a day. So what will that power? Quite a bit, as long as I’m only using what I need and not wasting any power. As you can see, I don’t have an air conditioner or electric heater in the list, that would use too much power for this system. But I can live quite comfortably in my tiny house, with all of the essentials.
If you need a bigger off-grid system than these, don’t fret, there’s larger off-grid home solar power systems available. All of the solar panels likely won’t fit on your tiny roof, but if you have some sunny space in your yard, a ground mounted or pole mounted solar system may be the perfect solution.
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