solar-powered homestead

One might be forgiven for thinking that tiny homes are generally for free-wheeling millennials looking to get out of the mortgage trap. After all, we do see a good amount of young people sharing their stories of tiny house bliss. But there's also a healthy contingent of more mature folks who have downsized and ditched large homes in favour of something that may be smaller, but offers more financial freedom.
Jody and Bill Brady are one such pair of intrepid people, who decided on a big life change. They describe themselves on their blog Simply Enough: "We're a couple in our 50s who decided we wanted to 'rightsize' our lives. We sold our big house and invested the profits in ourselves: we quit our jobs, did a lot of research and then designed and built our own 250-square-foot house in the Blue Ridge Mountains of Virginia." Or, as they tell Apartment Therapy, they once lived in a 3,500-square-foot house, and one day, while looking over their finances, they realized that "The house owned us." They made the switch by building their own smaller home.
© Simply Enough
© Simply Enough
In choosing to live more simply and sustainably, the couple chose to build with reclaimed materials whenever possible, which may take a longer time, but results in what Jody calls a more creative and "serendipitous design". Barn and pallet wood is used throughout their home, either on walls or for building furniture. Another good small space strategy: installing lots of windows and doors (this house has three leading to the exterior), so that light comes in and no one feels trapped in a small space.
© Simply Enough
© Simply Enough
© Simply Enough
© Simply Enough
© Simply Enough
The kitchen's storage drawers are made out of recycled pallet wood, while the IKEA pendant lamps also remix old colanders. The huge 30 by 18 inch sink has space for washing dishes, clothes and filling up garden pails. The stove is an alcohol-burning stove.
© Simply Enough
© Simply Enough
© Simply Enough
© Simply Enough
© Simply Enough
The couple's 12-foot-wide tiny house on wheels is situated on the side of a hill on a friend's property, and has been built to blend in with its surroundings as much as possible. When you live in a small space, it's important to have lots of time outdoors, so here there's a vegetable garden (their solar panels are placed here -- the home is 80 percent solar-powered), exterior deck, and a 160-square-foot screened structure that provides shelter while still being outdoors, perfect for entertaining or a pleasant cook-out.
© Simply Enough
© Simply Enough
© Simply Enough
So far, Jody and Bill have lived in their hand-built tiny home for a year and have no plans to return to a big home. To read and see more of their story, visit Simply Enough

Inverter String Design Calculation

How to calculate the maximum number of modules per series string when designing your pv system.

For many new to photovoltaic system design, determining the maximum number of modules per series string can seem straight forward, right?  Simply divide the inverter’s maximum system voltage rating by the open circuit voltage (Voc) of the module used and you’re good.  Well, that does get you in the ballpark, however you could be at risk of over-sizing or under-sizing the number of modules in a string depending on where you are located in the world.  So in order to spot check ourselves we can employ a couple of simple calculations to ensure that we do not encounter these set of problems.  There are a plethora of string sizing tools out there.  Some are from the inverter manufactures and others are intricate home-brew type tools.  These can be great to do the double checking for you, but often the module that we are using is too new, obsolete or simply not listed in the database of the tool that we are using.  Not to worry, these calculations are easy enough to do by hand or to input into a spreadsheet.
Let’s just dive in shall we?  I’ll set up a fictitious scenario with all the elements that we would need to be able to complete the calculations, including a module that is new enough that not many online string tools have it in their databases.
PV Module: SolarWorld Pro SW 320 XL Mono
The values that we need to collect from the data sheet is the Voc, cell temperature used for standard test conditions (STC),  temperature coefficient of Voc, maximum power point voltage (Vmp), and temperature coefficient of Vmp
Voc: 45.9, ºC @ STC: 25, TCVoc: -0.304, Vmpp: 36.7, TC Pmpp: -0.43

Inverter Model:  SMA Sunny Boy 7700TL-US-22

The two most important values to collect are the maximum DC input voltage and the start or strike voltage of the inverter.
600 Vmax, 150 Vstart
Now we need to dig up environmental data of the location.  There are two fantastic resources to use here and all you need to do is enter the zip-code of the location to find the weather data nearest to your location.  My next step is to go to SolarABC’s or SolarDesignTemps for the ASRAE data for Memphis, TN 38116.  I recommend the latter for areas outside North America for our international friends.
The important information to collect form either of these two sources are going to be record low, the 2% annual design dry bulb temperature and the expected rise in cell temperature due to mounting method (more on that here).
Let’s start by calculating the minimum number of modules that we should have in a series string.  This is a three part calculation.
Vmin = (Vmp + ((THigh + TRise - TStc) x (VmpCoef x Vmp/100)))
Vmin = 36.7V + ((35ºC + 32ºC - 25ºC) x (-0.43 x 36.7/100)))
Vmin = 36.7 + (42 x 0.158)
Vmin = 30.07 V
Next we should factor in system loses (de-rate factor).  We forgo this calculation for the purpose of simplifying this exercise and assume our derate factor to be 12% or 0.88
Vmin = 30.07 x 0.88
Vmin = 26.46
We can now take our result from the above calculations to determine the bare minimum number of modules we can expect to have in our system by dividing our DC start (strike) voltage by our Vmin.
150 / 26.46 = 5.67 rounded up to the nearest whole number.
The minimum number of modules in series can be a low as 6.
Now we can calculate the maximum number of modules that we can have in our system by doing a very similar type of calculation.
Vmax = Voc + ((TLow - TStc) x (VocCoef x Voc/100))
Vmax = 45.9 + ((-12ºC - 25ºC) x (-0.304 x 45.9/100))
Vmax = 45.9 + (37 x 0.14)
Vmax = 51.08
Now, divide our result by the maximum DC system voltage of the chosen inverter and round down to the nearest whole number.
600/51.08 = 11.74
The maximum number of modules in series can be as much as 11.
Now we have all the parameters that we need to design a system which will not go over the maximum input voltage of the inverter at record lows and will meet the minimum start up voltage of the inverter where cell temps are at their highest.
I like to keep a database of inverters and modules in a spreadsheet and populate the data needed in these calculations to save time, but you can simply plug these values into the formulas themselves if you are not too savvy with spreadsheets.

Support Topic: 

Solar panel

Inverter

Support Keywords: 

series string

string size design

open circuit voltage

9 Steps to Build a DIY Off-Grid Solar PV System

Day by day the price of solar panels falls gradually. But still, installation of a complete off grid solar system is costly. That’s why I decided to write this guide on how to get all the components of your solar system separately and assemble it all by yourself.
If you have decided to install a solar panel system to cover your home power needs, then this tutorial is for you.
I have tried my best to guide you step by step, from buying different components to wiring everything by yourself.
(Want to know about the 13 proven and best ways to generate power off-the-grid? Click to grab

The 13 Proven Ways to Generate Power Off-the-Grid)
You have to know some basic electrical and math for designing the entire system. I have also attached links of my other instructions to make the charge controller and energy meter.
For an off grid solar system you need four basic components

1. Solar Panel (PV Panel)
2. Charge Controller
3. Inverter
4. Battery

Here’s how all the pieces fit together:

How the solar system fits together

Besides the above components you need a few more things like Copper Wire, MC4 Connector, breaker, meter and fuses, etc.
In the next few steps I will explain in details how you can choose the above components according to your requirement.
Note: In the pictures I have shown a big solar panel of 255W @ 24V, two batteries of 12V @ 100Ah each, 30A @ 12/24V PWM solar charge controller and a 1600 VA pure sine wave inverter. But during the calculation I have taken a smaller solar system example for better understanding.

Homemade Medium size Biogas Plant for Kitchen waste

Homemade Medium size Biogas Plant for Kitchen waste

Final Product of portable Biogas Plant

 I always searching new techniques to produce biogas from animal and kitchen organic waste at house level in urban area, mostly biogas digester in the world are floating dome and fixed dome type biogas digester, these plant need large space and large quantity of organic waste. It can not build in urban area, I found on internet some portable biogas plant like ARTI biogas  plant and GREENTECH biogas plant these plant work fine, I inspired by ARTI biogas plant design so decide to make my on digester similar as ARTI plant.

See ARTI Biogas Plant Diagram  source Pakistan Science Club forum

ARTI Biogas plant is very simple and useful biogas plant can be made by plastic, steel tank, and bricks ARTI biogas plant consist on two part 1st is digester tank 2nd is Gas older tank, Digester tank also called fermenter where fermentation of manure takes place and biogas produces. Digester tank is made by 1000 liter water tank and gas holder made by 750 liter plastic water tank. PVC pipe also use as inlet and outlet.

Construction of ARTI Biogas Plant step by step Video Portal
Here a links visit http://paksc.org/pk/biogas-plant-design/...-tank.html

When I  was arranging material of digester I thought alternative of gas holder tank because it cost and extra working for cutting etc, so I decide alternate of gas tank to Old or used Tyre tube of tractor or large tube of Tyre. In this storage system I got two benefits, first I saved 3000 Rp and 2nd gas can be transfer.
Here is Photos of Step by Step Digester construction I hope you will learn and try to make.

 Components of the Bio-gas Plant.

The main components of the biogas Digester are a digester tank (Water Tank), an inlet (PVC Pipe) for feeding the kitchen waste, gas storage tank (Tyre Tube), an outlet for the digested slurry and the gas Pipe.

Material List Of Biogas Plant.

1. 700 liter water Tank ( used as Digester Tank)
2. 3 Inch Diameter and 3 fit in length PVC pipe (to be used as inlet pipe)
3. 3 Inch Diameter and 2 fit in length PVC pipe (to be used as out let pipe)
4. PVC Pipe adapter (to be used as funnel).
5. Iron nipple
6. Two PVC Pipe Caps
7. Two Elbow 
8. Plastic pipe 5 ft (to be used for delivery of gas)
9. Gas Valve
10. Supper glue (to be used for fixing of pipe)
11. Sand 

Tools required

 A hack saw blade for cutting the pipes and a soldering iron cutting holes on the tank

Step 1

Here are some photos of biogas plant tank and components. 

All Components of Homemade portable Biogas digester

700 liter water tank to be used as Digester Tank

700 liter water tank and other  Material for making of Plant

700 liter water tank and other  Material for making of Plant

Elbow, PVC Adopter Pipe, Glue, Valve

Step 2 Making of inlet Pipe.

I take PVC pipe and put on side of tank and make circle with the help of pencil it should be equal to PVC pipe diameter.

PIPe and Tank

Drawing a circle around PVC pipe on top side of the water tank

Drawing a circle around PVC pipe on one side of the water tank

Circle showing on top side of tank

making of hole with help of soldiering Iron

making of hole with help of soldiering Iron almost done

making of hole with help of soldiering Iron

making of hole with help of soldiering Iron

fitting of pipe inside the hole

Inlet PVC pipe fitted it shouldn't attach with bottom 

Cut the extra length of PVC pipe (should be equal to the tank cap)

making of hole with help of soldiering Iron side of the tank for outlet pipe.

PVC Pipe Adopter fix on Pipe

Inlet pipe and outlet pipe fitted in tank

fix the elbow with outlet pipe 

Make hole on cap of water tank and fix the iron nipple in it

Step 3  

sealed the joint of pipe with tank by supper glue and sand

Inlet system of biogas plant

Final Product of portable Biogas Plant 

(Note: Tyre tube not showing in this post it will be show on an other post with working of plant ) PVC cap will use at inlet and outlet pipe to hold back pressure of gas.

After two or three hours of wait to allowing all joints to get cured and become leak proof

Feeding Of Digester Tank

Initially, cow-dung mixed (with the ration of 50 % water and 50 % dung )will be fed in to the system, which anaerobically bacteria will start the gas formation . After a week gas tube filled with biogas, but this gas not burnable because of the quantity of methane gas has very low and other gases like carbon dioxide nitrogen and sulphide gas. afterward, you can use food waste, decomposable organic material and kitchen waste it should be diluted with water.

 You can get further information on kitchen waste based  Bio-gas plant at Pakistan Science Club'w website www.paksc.org/pk/biogas-plant-design