Tiny House - will it work?

[Isakura]

Hi folks, new to the energy forums. My SO and I are looking to move into a tiny house in the near future, but we'd like to be able to be self-sustainable if possible, even considering going off-grid. Does anyone have any experience or know anyone who has successfully used Tesla Powerwalls and/or solar with a tiny house? In addition, we currently have a model Y (LOVE IT), which would need to be charged as well (however, we may have a garage on our property that may or may not be hooked up to utilities which is where it would be housed/charged, that is pending). Thank you!

 

[jjrandorin]

Hi folks, new to the energy forums. My SO and I are looking to move into a tiny house in the near future, but we'd like to be able to be self-sustainable if possible, even considering going off-grid. Does anyone have any experience or know anyone who has successfully used Tesla Powerwalls and/or solar with a tiny house? In addition, we currently have a model Y (LOVE IT), which would need to be charged as well (however, we may have a garage on our property that may or may not be hooked up to utilities which is where it would be housed/charged, that is pending). Thank you!

I would not plan on powerwalls if you are thinking about being "off grid", which in the sense you are talking about is true off grid, with no grid connection. You could likely do solar, but I dont they do powerwalls in an off grid setup.

You will likely want to explore some other battery technology instead for your off grid usage. Also, unless you only drive local, you might need to really plan for how much power that model Y uses (which will almost assuredly be more than the amount your home uses each day). You will likely need to have your solar ground mounted and have a decent amount of land to put it on to achieve charging that Y off of energy from PV. It will probably use twice as much energy even driving it around town as you would likely use in a tiny house.

 

[gpez]

I'm a bit disappointed that Tesla hasn't fully enabled off-grid Powerwall operation. That said @Isakura the Powerwall + PV is very doable for self-sufficiency but as @jjrandorin mentions it does need a grid connection even if you don't actually use the grid. That may actually work in your favor if you have net metering with your local utility and end up getting utility to the garage for your Y because then you don't have to run a line from your home to the garage and then any excess solar production would then go to the grid which would offset the grid usage for charging the Y.

 

[Isakura]

Thank you for your responses! As it is we are still looking for land to purchase and because the other half would like a workshop of some sort, the grid probably will end up being a necessity anyway. However knowing we can use solar plus the powerwall with a grid hookup and use that to cut down grid usage and assist during g outages will still be worth it.

 

[Patrick66]

Best to have the Powerwall in a permanent structure rather than a tinyhouse. The garage sounds like the right place, and much easier to put additional PV on the roof.

 

[BrettS]

There’s really little disadvantage to being connected to the grid. Even if your solar is meeting 100% of your needs about the worst thing would be the minimum monthly connection fee, which is usually only about $10-$15 per month. And if your garage or shop is going to be grid connected anyway then you’re already going to be paying that fee.

The grid connection also has the advantage of being able to supply power if you do wind up needing more than your solar can provide at some point, or if you have a solar or battery system failure.

It also can be cost effective because the solar will produce much less power in the winter than the summer, so you will have to pay more to have a larger system to cover your winter power needs and that means that you may have excess power in the summer. Instead if you try to size for somewhere in the middle you might have to pay a little for some grid power in the winter, but it would probably be considerably less than you would pay to get a system large enough to meet 100% of your winter needs. Additionally, if your utility offers net metering, then you can get credit for any excess production in the summer and use that power in the winter.

 

[wjgjr]

There’s really little disadvantage to being connected to the grid. Even if your solar is meeting 100% of your needs about the worst thing would be the minimum monthly connection fee, which is usually only about $10-$15 per month. And if your garage or shop is going to be grid connected anyway then you’re already going to be paying that fee.

The grid connection also has the advantage of being able to supply power if you do wind up needing more than your solar can provide at some point, or if you have a solar or battery system failure.

It also can be cost effective because the solar will produce much less power in the winter than the summer, so you will have to pay more to have a larger system to cover your winter power needs and that means that you may have excess power in the summer. Instead if you try to size for somewhere in the middle you might have to pay a little for some grid power in the winter, but it would probably be considerably less than you would pay to get a system large enough to meet 100% of your winter needs. Additionally, if your utility offers net metering, then you can get credit for any excess production in the summer and use that power in the winter.

And to add to that, the grid hookup also means rather than wasting solar power (which is virtually inevitable with an off-grid setup when trying to be fully self-sufficient) you are now supplying that clean energy to the grid, which in principle helps reduce the use of less clean generation methods.

 

[Vines]

Powerwalls do work off grid, and can be setup to control a generator that functions as the grid connection, so this is possible.

Whether its a good idea depends on your situation, but around here even if a house runs a net of zero energy from the grid, it maintains its connection for all the reasons posted above.

 

[jjrandorin]

I didnt even know it was possible, but of course you would know one way or another . not like I would ever do it, but in your above setup (powerwall setup to control a generator) does that mean the generator is "always on" functioning basically as the "grid" to the powerwall?

 

[Vines]

Running the genset 24/7 would be pretty inefficient.

Fortunately, there are a set of pins in the GW2 board that will control a generator circuit. This is only enabled in off-grid mode.

 

[Darmie]

I bet it's a great feeling to be off the grid. I'd love to one day but still need high speed internet. maybe starlink will kick in soon enough.

 

[jjrandorin]

Running the genset 24/7 would be pretty inefficient.

Fortunately, there are a set of pins in the GW2 board that will control a generator circuit. This is only enabled in off-grid mode.

Gotcha... so in that scenario, the genset generator basically becomes "the grid" for the gateway / powerwall setup, and the gateway turns on and off " the grid:" as needed with "the grid" in this case being the generator?

Very interesting! Not like I would ever do it (I want the best of both worlds, so I want to be grid tied, but net zero energy usage from the grid or as close as possible, anyway), but very interesting to know "it can be done, given the correct set of equipment".

Thanks, learned something new!

 

[jrweiss98020]

My SO and I are looking to move into a tiny house in the near future, but we'd like to be able to be self-sustainable if possible, even considering going off-grid. Does anyone have any experience or know anyone who has successfully used Tesla Powerwalls and/or solar with a tiny house? In addition, we currently have a model Y (LOVE IT), which would need to be charged as well

A Tiny House is nominally 8x12'. A 335 Watt solar panel is nominally 4x6'. That means if you have a single-slope, south-facing roof, you can get 4 panels for about 1.2 KW AC on the roof. The Powerwall would have to be placed outside the house, or else take up space you probably don't want to give up inside. It would take 2+ days (11 hours of full sunlight equivalent) to fully charge a Powerwall, even if you used NO power in the house during the sunny period. You would have to estimate your overnight power usage to find whether the 13 KWh available in the Powerwall would be sufficient overnight (as an example, a single 1000W space heater would fully deplete the Powerwall overnight if run continuously).

Charging a car on that system would be impractical, unless you only used the 120V charger and could operate on the 4-5 mi/hour of charge it would take at that rate. Since the charger would draw about 1.4 KW, it alone would deplete the Powerwall in about 9 hours.

 

[gpez]

A Tiny House is nominally 8x12'. A 335 Watt solar panel is nominally 4x6'. That means if you have a single-slope, south-facing roof, you can get 4 panels for about 1.2 KW AC on the roof. The Powerwall would have to be placed outside the house, or else take up space you probably don't want to give up inside. It would take 2+ days (11 hours of full sunlight equivalent) to fully charge a Powerwall, even if you used NO power in the house during the sunny period. You would have to estimate your overnight power usage to find whether the 13 KWh available in the Powerwall would be sufficient overnight (as an example, a single 1000W space heater would fully deplete the Powerwall overnight if run continuously).

Charging a car on that system would be impractical, unless you only used the 120V charger and could operate on the 4-5 mi/hour of charge it would take at that rate. Since the charger would draw about 1.4 KW, it alone would deplete the Powerwall in about 9 hours.

It's a good call out about the limited roof space. I know some tiny homes are designed to be able to be towed but if it's intended to remain stationary and you have more real estate one could always install stand alone panel mounts in the yard. Plus there is the workshop roof.