Tuesday, August 21, 2012

Handymans solar installation; some tips and recommendations.

I am NOT a fan of the harbor freight Solar panel package.   IT uses a type of very low grade solar panels that will not last for more than 5 years and they are delicate sheets of glass.    But, they are readily available and Harbor Freight has made them easy to use for the typical handyman kind of person.

IF you wanted a low capacity Solar electric system for a cottage or micro home,  Here is how to get started.

First I recommend buying 3 of their solar kits to get started,  if you are really low on cash,  then two will  work for now, but you will not have enough solar panels.  You also need their Solar expansion hub, a couple of batteries and a Power inverter.

http://www.harborfreight.com/45-watt-solar-panel-kit-68751.html is the solar kit.
http://www.harborfreight.com/8-panel-universal-solar-connector-68689.html is the solar hub.
http://www.harborfreight.com/30-amp-solar-charge-controller-68738.html the higher capacity charging controller.

You need to get  1 or more batteries for power storage.   They must be Deep cycle type of batteries,  you want to size the battery to be 10X to 12X that of the solar output.   a single Harbor freight kit will put out 3 amps at PEAK power generating.  so you want a 30AH battery to pair with it.   we will be putting together 3 kits to get a max of 9A of power so we want around 100AH of battery storage.  One battery will work if you don't want to use two. Don't even think of using car batteries, they will not last more than a couple of months as they are not designed to be drained down to empty and recharged.  Deep cycle marine or backup power type is what you need.

Now your run time for the inverter is going to be low.   1000Watts at 12 volts is 83.3amps This means you will use 83.3Amp Hours of battery capacity in one hour.  While your charge rate is 9amps into a 100AH battery will  recharge the same amount of power in 10 hours.  This is assuming that you can have 10 hours of 100% output.  In reality, it will recharge the battery in 20 hours on a sunny summer day,  or about 2 weeks in the winter on a partly cloudy day.

This means we cant run that inverter very much, this is the problem with really cheap solar.  But let's work around this.   Let's eliminate any 110Vac capability.  Sorry, no hair dryer or microwave oven.  A typical small 800 watt Microwave will use about 5Amp Hours of Battery storage for every minute it is running and the inverter is running.  That means for every minute you run it, you will have to have about an hour of strong sunlight to replace the power that it used.  That bag of microwave popcorn you want that cooks for 3.5 minutes will use up all the electricity your solar system made for 1/3 the day.

The charger and controller that comes with the solar kits support 12V lighter ports, so everything you own will need to be for use in a car or run on 12 volts.  you can easily wire to the battery larger gauge power cables to wall plate 12 volt power ports to support your cellphone charger, a laptop charger, or a fan.   In fact look at RV shops or Truck stops for a ton of appliances that run off of 12 volts.   just don't get the silly things like the frying pan, coffee maker, or other high amperage devices.

You can use regular home light switches to put in 12 Volt lights, and wire them just like a home light.  but you only need 2 wires.  Ground and 12V,  have the switch wired to the 12V and ground runs through.

Run all the solar panels to the 30 amp solar charge controller.  with multiple panels you are going to not use the controllers that come with the solar panel kits.   Yes, I wish they just sold the panels.  then hook up the battery to the charge controller.   You can use one of the 45 watt kit charger controllers as a power supply and voltage meter, just hook up only the battery side.

You are all done now,  you have a basic solar power setup that has a couple of CFL 12 volt lamps, and two charging ports with a controller and a volt meter.  Plus enough capacity to go all night with lights or your basic low power needs.

If you want it ran to more convenient locations, you need to run low voltage wiring and add in fixtures and outlets.  That means getting a bit more advanced.

You need to also get a fuse panel if you are going to go any further,   Either a boat or car fuse panel and run all power runs to the panel.  a Ground buss bar is also a good idea.
http://www.the12volt.com/Default.asp? is a good website that is car specific and audio specific but has a lot of good tips on how to run and wire 12 volt systems.  http://www.examiner.com/article/how-to-wire-your-off-grid-cabin-with-12-volt-lights is a nice article about 12 volt wiring as well for cabins.

RV and marine shops have 12V lighter outlets for power outlets you can use.   fuse each one at 10 amps and run good quality 12awg wiring to each one and home run it back to the fuse panel.

Want to generate more power?   think about adding a small wind generator.


Sunforce has a nice little wind generator that is only 400 watts at 12 volts, but it's a LOT stronger than the solar panels we just talked about.   400 watts = 33Amps.   Now this is at peak,  you almost never get peak except during a hurricane.  Assume 1/5rd the power output on average.  so 3-4 amps when the wind is blowing.

This coupled with the solar install will give you a very nice off grid power system.   Granted it's not the best, but it's all readily available to most people by driving to their Harbor Freight and Northern tool stores.  About $1500 in parts total to give you off grid power.

This is not how I would go.   Except for the sunforce wind generator.   I'd get two of those.   Next time I'll detail what I am buying and using.

Here is a hint,  it's more like this.....


Except not sold by sunforce.

What I would actually use is very close to what is sold here .....

http://www.amazon.com/Go-Power-Solar-Elite-Complete/dp/B0015398PE/ref=sr_1_2?ie=UTF8&qid=1347551114&sr=8-2&keywords=200+watt+solar+panel is a complete kit of what I would install.  it is a starter kit at 310 watts and by adding a 3rd panel bring it to 470 watts  and stays manageable for the mobile micro home.   all three panels and their stand can be disassembled and put inside for transportation.  Plus generating 470 watts an hour will charge up the system quickly on winter days when you only have on average 2-4 hours of direct sunlight (non overcast)  during the summer sunny months or southern locations it will be more than enough to supply the power needed.   470 watts will deliver enough to charge and run two laptops at full tilt, run a stereo, charge your cellphones as well as have some power left over to charge the batteries with what is left over.  In a micro home I can not see needing more than this for electricity.   Now if you want to do something extreme like spend the winter in Nome Alaska with your micro home,  you will have some power issues.

I do recommend having a battery storage bank of at least 600 amp hours.  That will deliver around 3600 watt hours (at 50% discharge)  of power for extended stormy days.   I recommend you build a box for your batteries. Put the batteries in it with nothing else but the connection cables on the terminals and a fuse. No electrical devices in the box at all. Install a flue in the top to allow the fumes to escape out the top and outside of the building. Never ever put and inverter or charger or controller in the same space or box with a lead acid. The fumes will ignite.

Do the math on how much battery power is required to run your load for 24 hours in watts. Divide the watts by DC voltage (12 volt battery, 24 volt battery..) and you have the amps you need. Double that for 50% rate of discharge and you have the battery size in amp hours. Size the inverter to cover the heaviest load you will put on it at any one time. Extra solar batteries and solar panels are always of use.

Monday, August 20, 2012

Getting Closer to smaller living: Stage 1.7 - Ventilation

Ventilation.  This is HIGHLY important in any home, and triple important in a micro home.   You need to change the air,  draw out spells and moisture from cooking, as well as the bathroom moisture and smells.    Problem is your choices in a micro home are limited,  Full sized home vent fans are far too large for a micro home, and they require 110Vac to run.  If you are planning on being off grid, this is a problem.  They also will draw more air than you really want for the smaller spaces.   yes a bathroom fan that will suck all the air volume that the house has every 5 seconds would be great on bean chili night.  but it will be really noisy and difficult to install in a smaller space.   RV vent fans are another option,  they are designed for smaller spaces, but are horribly expensive for what they are.    My vent fan of choice is the boat bilge blower.

These fans are very small and easily ducted to where they are quieter and they run on 12 volts using a small amount of power.  you can use one in the bath to vent the bathroom,   one in the kitchen, and another at the peak of the house to draw hot air outside during the summer. The nice part is that you can mount all of them in one location where they are screwed to blocks of rubber to isolate the noise and vibration and are accessible for easy servicing.  If you put a filter or filter material over the intake inside the home, you can make sure the fans don't get caked with dust and lint, as well as keeping he ductwork clean.  the duct can be PVC pipe or flexible pipe.  Most of these fans will move 240CFM or cubic feet of air a minute.   240 CFM is a 6 foot by 6 foot by 6 foot cube of space.   Meaning one of these fans will change over ALL the air in a 12X24 micro home every 4 to 5 minutes.   That's plenty!

Now If you think about this,   you don't need a LOT of fans.   one in the bathroom and placing the kitchen outside the bathroom will take care of moisture and smells.   The problem with kitchen cooking is having a real vent hood that will take smoke out and handle the high heat of cooking.   This is where a RV store will come in handy.   I strongly suggest getting a steel or stainless RV stove vent hood and fan and putting it in your kitchen.  over the stove is best, but if you are only going to have a hot plate, then where you will cook with the hot plate is a good idea.    Yes it takes precious space,  but if you have a kitchen mishap, it's nice to be able to draw all the smoke out fast and not worry about the vent hood.

Consider a hot summer day,  if you fired up the loft vent fan and opened the windows in the house on the opposite side of the loft ladder, you will have a constant breeze coming in of cooler air. from the windows.

but let's get clever.  if we had controlled vents UNDER the house that drew air from near the ground outside,  we would draw in even cooler air into the home.   This is why a lot of old homes  had basement windows.  you open the upstairs attic windows, open the doors to the attic and basement and then open the basement windows.   Hot air leaves the roof while drawing in the coolest air from near the ground.  You can cool a house significantly this way.  It will feel cooler than what it feels like outside.   Even cooler if you are in a shaded area and are pulling air from a shaded grassy area.

Problem is you will need air filters to keep dust from coming in the house, just cut some filter material and stick it over the vent holes or roll up some and stuff it in the pipe.  check it and clean it often, every couple of months, just like your home furnace filter.

Quickie: visualizing size

Trying to visualize sizes of space and furniture will give a novice in Smaller living a better idea as to why most  people choose custom furniture or better yet built in's for their micro home.

http://www.urbanbarn.com/Room-Planner is a nice little room planner,  if you specify a custom room of 10' by 12'  you can see how conventional furniture is all over sized and waste a LOT of space.

Just a way to help you visualize the space and how to start thinking how to save that space.