# Forums

## Trying to estimate power need etc

Good evening folks... FYI i am a model s and 3 owner, but no energy products.
I am in the process of purchasing land (hopefully) that will likely be off grid. I am hoping to install solar and a powerball.
The only reason we need power is there MAY be a 40x20 metal build on the land. Inside will be a basketball/volleyball/tennis/whatever court. Maybe a bar and some storage.
Power need shouldnt be more than lighting, and some ancillary things.
My question is, would you expect 1 powerwall would be able to keep that building running (knowing its mostly lights, maybe a fridge) for 5-10 hours? Im pretty new when it comes to this stuff so I am trying to figure out how many panels id need (in iowa), if all i needed to do was top off the powerwall.
just starting this process.
thanks

Dsmtesla | 15 avril 2018

well, apparently tesla solar doesnt work in my state. they arent selling here yet. so if I did some other solar company id have to do a lot of research on what is good and what sucks :(
ive actually been doing a lot of research in to just doing some solar and a couple powerwalls at my house.
my monthly useage is about 2000kwh so 75kwh per day roughly.... not sure how all that math works out :(

deweyvt03 | 18 avril 2018

I have two refrigerators and a deep freezer along with some PCs and other devices that are always running. I average about 600 W in the background to keep those things running. When the lights, HVAC, water heater, etc, kick in, that is when I see jumps in usage up to 8,500 W.

So- if you are building this "butler building" (building style that is metal pop-up) and having a fridge and LED lighting (HVAC?) and your equipment runs around 400 W when idle, then that would take 4 kWh to run for 10 hours. But if you plan on occupying the space during the night, you can anticipate a larger draw.
[Basic math is that you look at the draw at a specific moment and multiply that by length of time. Also consider it the "area under the curve" if you are looking at usage graphs.]
PowerWall2 holds about 13.5 kWh of energy. So I imagine one would suffice to cover just that building, and you would need enough solar to power the appliances during the day and simultaneously recharge the battery that was used overnight. The battery can also supplement on shady days.

But, it is worth noting, that shady days reduce my solar generation by 75%. Have a couple days in a row and you may be out of power if you are not backed up by a grid source.