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Best energy (solar really) for 8x8 tiny 'home'

 
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IDK all the basic info you need to answer so ask if I missed a vital part.  'House'= 8x8.  Insulation= good but I might shore it up if needed.  No access to hydro; not much wind.  Geothermal (underground aspect) is out.  We get a lot of sun but a generator is part of my plans, preferably a solar or other natural input type.  In winter I kept my room around 60 degrees and was fine and on very cold nights I kept it around 50 or 55 and the heater ran a whole lot less during the day or night than I expected; except in the very cold (it was .  This is E TN so it is very rare to get into the single digits.  The summer I keep around 78 but could probably deal with it hotter but if I can cool it without paying a crapload more for solar/etc then why not.  At night it is still in the 60s and this entire month (July) it isn't supposed to get over 70 at night.  On that note, any heaters or air conditioners that are best for this size.  Also NOTE that this is on my mom's property so if the temperatures got crazy I can survive in her home.

So the easy choice is solar panels/generators/etc.  By my calculations it seems about 500 watts would be needed for heating which should be enough to keep it cool enough for me since I can deal with heat better than cold.  I just don't know what is good or not (whether brands or sizes or anything) in this field and what will work or not so do you have any recommendations?  I need just a laptop (30W).  I rarely have my phone (5W) even on.  I use cold water.  I mostly eat raw but I sometimes use a slow cooker (about 108-162 watts from what I looked up).  And I might add a Nintendo Switch (18W to charge).  The initial idea was to get enough to run all I wanted (laptop/etc) and then add more later but perhaps it is cheaper to buy 'bulk' solar.

I love the idea of a bike generating energy but IDK if that'd be easy to build.
 
pollinator
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I recommend adding R-50 insulation to the roof, floor and walls. That way you will need alot less energy for air conditioning/heating.
I like the idea of recharging a 24v or 48v battery pack at work or your mom's house every few days. This battery pack could be part of your ebike. So you could even power it by pedaling.

Your 8ft x 8ft structure can fit 1500W of solar panels (3x 500W). Generating about 5KWHr per day.  This ac unit
 
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Here's a link to a local Craigslist seller that has inexpensive panels. They look like they might be a good deal.  Whenever I buy panels off Craigslist, I always bring a voltmeter with me so I can test each and every panel before it gets placed in my truck.  Look for numbers within 10% of what the Voc is documented as.
https://nashville.craigslist.org/mat/d/knoxville-solar-panels-from-60-on-up/7633080224.html

A good rule of thumb is to have twice as many watts as whatever your biggest load is.  So, if your biggest load is a 500W air-conditioner, get at least 1000W of panels.  Maybe four high-voltage grid-tie panels like what this guy is selling (he says 6 minimum?)

Don't stick with 12V.  24 or 48V is a better choice for anything that does not have wheels.  Four 6V golf-cart batteries, such as Trojan T-105, would be good.  CostCo also has a 210Ah golf-cart battery for 110$.

If you bought four or six of his panels, wire them at least two in series.  For four panels, that would be written out as 2S2P, meaning you have two parallel strings of two panels in series.  Feed that into a controller like Epever's Tracer AN 4210.

For running your air-conditioner, get a quality sine-wave inverter.  Cheaper MSW inverters will quickly kill anything an electric motor.  Take a look at Samlex's PST24-1500.  It's UL-listed.
 
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Link to search a/c specs: https://www.energystar.gov/productfinder/product/certified-room-air-conditioners/

How to install a window air conditioning unit through a wall:  https://m.youtube.com/watch?v=dJm2ajwdbHs

The average electrical power used by an a/c can be calculated as: 5000 (BTU/hr) / 12.2 (EER) = 410 watts seasonal average. The surge power when the compressor starts is at least 2.5 times more.  (inverter output needs a minimum of 1000 watt surge rating, 1500 w may be more typical).

There is a newer type of a/c with EER of 15.  https://www.tcl.com/global/en/blog/what-is-the-difference-between-inverter-and-non-inverter-ac  It costs about $160 more but uses 80 watts less, or $2/watt saved.  $2/watt is near the same cost as solar panel installation.  So, if you’re running an a/c only on sunny days, any type of a/c can work. However, if running overnight on batteries, the cost of the more efficient a/c is justified by the savings of needing fewer batteries.

The cost of all this equipment adds up, and seems to quickly go north of $2000. A cheaper solution might be to build some kind of earth berm, or otherwise use passive ground-source geothermal, eg as used in a greenhouse “climate battery”.  It’s a few inch diameter pipe buried underground with a fan to circulate air.
 
pollinator
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What does IDK mean???

With such a small home you could experiment greatly with it to get great results.
As S. Benji suggested look at your insulation and look at the underfloor.
Look at my Safari double roof if temps are hot.
Think about creating air movement when you need it with air towers.
I think heat from solar panels is hard, but what about a good wood stove. or Rocket Mass Heater?
I have solar air heaters that work well.
 
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John - IDK = I Don't Know

E Tennessee is really humid, so desert-mode cooling towers don't really work there. But if you could catch a breeze and at least stir the air up that would be something. Fans don't take much juice and in a small space that could be enough.
 
pollinator
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Interesting suggestions so far. I would not waste my time on an inefficient wall mount ac if the budget allows go straight to the heat pump options. There are lots of self install options out there and it's a 1 inch penetration through the wall not a 2 square foot one and it will heat and cool... Powering it will mean a strong inverter and a good battery bank but your small home can become a battery. A cement slab is a great heat sink, drywall on walls can offer hundreds of pounds of mass, ceramic tiles same thing. You can over crank the cooling or heating while the sun is out and coast through the night mostly. That in itself is a battery. You have more winter sun than I do here so you might be able to make it all work year round without additional heat. Build you power system for growth and skip the 12 volt gear from the beginning to avoid an expensive switch over later ...
Some things to think about.
Cheers, David Baillie
 
Benjamin Abby
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Sorry, I haven't answered as quickly as I wanted.  I've been researching these things but I've been very busy and didn't expect it.  I wanted to have a better clue but I'm taking it slow to make sure I do it right the first time.  Thank you so much and every response was great and I seriously took ideas from every single one of you so I gave you all thumbs up.

Luckily, the heat and AC isn't a big issue.  The hottest it gets is usually 90 with rare 100+ days which I can handle.  I'm out working in it a lot so sitting there isn't so bad and the fan should be enough; sometimes I just go deep into the forest or I'll hit up a friend or family nearby (half my neighbors are family for now but with prices skyrocketed who knows).  At night it usually cools down enough I don't need anything to sleep so I'll probably get some solar just for a little extra push (IF I go the mass rocket heater or woodstove route for a main source of heat).  Geothermal is something I'm very ignorant in so I'll be checking that out but that suggestion seems very simple.  The insulation is a big one and I'm hoping for a natural one and I'm trying to source it locally BUT that is part of the research.  One thing I'm checking on is if it is better to get all this upfront or if I can piece it together slowly and get better deals due to patience because I think it is better to have extra power if needed so in the long run I'd want about 1,500 watts of solar like suggested (at least 1K like Michael suggested).  Charging the battery with the Ebike is definitely something I want to include.  I didn't know golf cart batteries were good for this; I was just going to get a generator.  I'm guessing the quality sine-wave inverter is necessary for the heater also, I just want to be sure.  I have never even heard of the Safari double roof but I love the look and I was already thinking about building a lean-to around the sides but I've also thought about a greenhouse due to extra windows.  Maybe I can make it a lean-to/safari double roof thing.  and I'll definitely check into the solar air heaters.  I also thought about an outer layer room built of cob and strawbales since I have lots of clay and a bit of straw.  I've experimented with cob bricks but never made a structure like this so I'm playing around with cob but don't exactly trust it and I don't know anyone local that does it.
 
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While you're researching, may I suggest you also research "thermal mass"? (our new forum would be a good place to start: https://permies.com/f/504/ )
I don't know exactly what your small house looks like - is it moveable, could you put some insulation like an apron around it so that the ground beneath it becomes the mass etc... Your comments about cob bricks fit with this concept.

We travelled in a travel trailer in the past - granted in a colder climate and it wasn't well insulated - but the issue was that with no mass, there was nothing to hold heat and no mass to gradually heat back up if we'd used the air conditioner. In other words it was a yo-yo bouncing from too hot to too cold, and the fans doing this were very noisy which drove me whacky in a relatively small space, although larger than 8x8.
 
John C Daley
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Benjamin
Look for adobe, mudbricks or earth compressed bricks [ ECB ] that should show you heaps.
They may be the oldest building material known so they do work.
 
John C Daley
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Wool from cross bred sheep is not used for clothing and makes good insulation.
https://havelockwool.com/
 
Mike Philips
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I think sometimes a great engineer might not be a great salesman, and the merits of each could be lost on a sea of ideas.
 
Benjamin Abby
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Mike, you make a great point but I like having plenty of options personally to look at.  I don't have to rush but I should be fine until mid-October but really November is when it starts getting frost level cold more regularly.  With that much time I'll look for sales and hopefully find exactly what I want but if a great secondary option becomes crazy cheap or even free I can jump at it with more confidence than if I had never heard then researched it a bit.  

The sheep wool I checked into a bit.  Excellent stuff.  The "why wool in 100 seconds" (https://havelockwool.com/) from the site John suggested is exactly why I wanted to simplify and build as much as possible myself (too many toxins otherwise).  And I assumed the durability was bad but looking into that surprised me when some sites said this should last 60 years or so: this is just like cob which I bought into as poor people's buildings and thought it meant it was cheap and wouldn't last.  I was going to try Jon Jandai's mudbrick making.  I like a lot of his stuff.  The hemp wool insulation is very appealing after researching it a bit and is my current favorite.  Anybody ever tried it?  I was very surprised the price was astronomically more expensive than fiberglass.  

I can't move it personally but it is moveable by a huge truck.  It has 4 cinder blocks underneath about 2 feet in from the edges which holds it up and the ground has a lot of rocks/slate under that.  The apron should work around it.  I thought about the concrete slab between the house and rocks or even cob since some say it regulates indoor air better than concrete/bricks (which release heat quickly).  Due to inexperience I have no clue if that would work.  I know I'd have to make sure water doesn't collect around the cob.  Perhaps a thin slab of concrete would work to make sure the cob is elevated off the ground.  I can tone things out amazingly well so a fan won't (most likely) bother me.  
 
John C Daley
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even cob since some say it regulates indoor air better than concrete/bricks (which release heat quickly).  


From the Thermal mass topic, cob, concrete and brick all have similar properties with regard to heating and cooling times.
 
Jay Angler
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John C Daley wrote:

even cob since some say it regulates indoor air better than concrete/bricks (which release heat quickly).  


From the Thermal mass topic, cob, concrete and brick all have similar properties with regard to heating and cooling times.


I have heard that cob can have an effect on humidity - it will absorb moisture during damp parts of the year, and give it off during dry periods.
That said, how well that works may be dependent on exactly what your climate averages are.
 
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