Planning an off-grid solar system.

Estimating Energy Generated by your PV System

Using the equation below, you can estimate the annual electricity production and electric bill savings for a grid-connected home solar electric system with a net metering arrangement.

Determine the PV system’s size in kilowatts (kW).

A typical range is from 1 to 5 kW. This value is the “kW of PV” input for the equation below.
Based on your geographic location, select the energy production factor from the map below for the “kWh/kW-year” input for the following equation.

Electricity production from the PV system

kWh/year = (kW of PV) × (kWh/kW-year)

Calculate the watts if you know the voltage and amperage of a device.

Watts = Volts x Amps

If your T.V. plugs into a standard 120 volt receptacle and uses 4 amps, the total watts is calculated by multiplying 120 volts x 4 amps. That equals 480 watts.

120 Volts x 4 Amps = 480 Watts

Diagram of a simple solar stand-alone PV system

Meagle Sun

Some simple examples of rural off-grid power provision.

Masonry heaters & stoves


Many people currently cook in a microwave oven. It’s called “micro” because the high-frequency radio energy used to jiggle the food’s water molecules has a very short wavelength. We call our stove the macrowave because, even though it utilizes radiated infrared energy (heat) which has a much higher frequency and even shorter wavelength, the stove itself is so much larger.

Read more about masonry stoves, and homesteading in general at the Geopathfinder ( site.

A collection of straw bale resources

Straw bale building guidelines for wet and humid climates
Climate and Straw bale construction
Five tips for keeping straw bale walls dry in a wet climate
Yes you can! Build with Strawbale in Wet Climates
Moisture and straw bale walls.
Sun Plans
Strawdio Template
Straw Bale Futures
Passive Solar Design
Lime paint, lime wash and paint lime wash in Edinburgh Scotland
IronStraw – Calculating How Many Bales of Straw You Need
Harvest Homes: Straw Bale Material Calculator
Green Building: From the Basement to the Roof
50 straw bale house plans
Descriptions of solar homes from the owners
International Straw Bale Registry Project
Straw House – Home
Straw Bale Articles |
Magyar Szalmaépítők Egyesülete
Solar Haven – self sufficient living without utility costs or a big mortgage … straw bales resources [Austrian/German site]


Common-Sense Compost Making by the Quick Return Method

by Maye E. Bruce


This book describes a way of making compost, i.e. humus, which is simply, labour saving (no turning) and quick, both in ripening the compost and in getting results in the soil. It is adaptible to all conditions and to every size and type of garden, allotment or farm, the process being based on nature’s own methods.

Miss Bruce tells how to make use of the natural heat of disintegration, which liberates the vitality of the plants; how to retain that vitality within the heap, and how to quicken both the disintegration of plants and the energizing of humus by treating the heap with a simple activator. This is a herbal solution which contains in living plant form the chief elements necessary to plant life; formulae are given.

From Vegetable Waste to Fertile Soil affirms a belief in the universality of Life, this Life being manifest in varying ‘rhythms’ in the mineral, vegetable, animal and human kingdoms. Health, productivity and perfection of growth in the vegetable kingdom, says the author, can best be achieved by feeding plants within the ‘rhythm’ of this kingdom.

Common-Sense Compost Making by the Quick Return Method

Rainwater harvesting calculator.

One millimeter of rain on one square metre of roof equals one litre of water run-off

To calculate the approximate amount of rainwater you are likely to harvest, use the following formula:

Estimated Net Runoff from an Impervious Catchment Surface Adjusted by its Runoff Coefficient

catchment area (m2) x rainfall (mm) x runoff coefficient = net runoff (litres)

Run-off (litres) = A x (Rainfall - B) x Roof Area

A is the efficiency of collection and values of 0.8-0.85 (i.e. 80-85% efficiency) have been used (eg Martin, 1980).

B is the loss associated with adsorption and wetting of surfaces and a value of 2 mm
per month
(24 mm per year) has been used (eg Martin, 1980).

Rainfall should be expressed in mm and Roof Area in square metres (m2)


In an area receiving 600 millimetres of rain a year with a rooftop catchment surface that is 11 metres long and 4.55 metres wide, and you want to know how much rainfall can realistically be collected off that roof in an average year. You want a conservative estimate of annual net runoff, so you use a runoff coefficient of 80% or 0.80.

catchment area (m2) = length (m) x width (m)

2 x (length (m) x width (m)) x rainfall (mm) x 0.80 = net runoff (litres)
2 x (11 m x 4.55 m) x 600mm x 0.80 = net runoff (litres)

100m2 x 600mm x 0.80 = 48,112 litres

48,112 litres = net runoff

A realistic estimate of the volume of water that could be collected off this 11 meter by 4.55 meter roof in a year of average rainfall is 48,112 litres.

A 1-acre self-sufficient small-holding


We’re shopping for land in Hungary and while prices are relatively low, when compared to those in Scotland, it’s possible that our budget will only stretch to a 1-, or 2-acre plot. Ideally we’re looking for 4 or 5 acres minimum however 1 or 2 acres will be suitable.

With this in mind I’m collecting information and learning how to “survive” on smaller plots.

Download: Start-a-1-acre-self-sufficient-homestead

Optimum orientation of solar panels

To get the most from solar panels you need to point them in the direction that captures the most sun. But there are a number of variables in figuring out the best direction. This page is designed to help you find the best placement for your solar panels in your situation.

This advice applies to any type of panel that gets energy from the sun; photovoltaic, solar hot water, etc. We assume that the panel is fixed, or has a tilt that can be adjusted seasonally. (Panels that track the movement of the sun throughout the day can receive 10% (in winter) to 40% (in summer) more energy than fixed panels. This page doesn’t discuss tracking panels.)

Solar panels should always face true south if you are in the northern hemisphere, or true north if you are in the southern hemisphere. True north is not the same as magnetic north. If you are using a compass to orient your panels, you need to correct for the difference, which varies from place to place. Search the web for “magnetic declination” to find the correction for your location.

The next question is, at what angle from horizontal should the panels be tilted? Books and articles on solar energy often give the advice that the tilt should be equal to your latitude, plus 15 degrees in winter, or minus 15 degrees in summer. It turns out that you can do better than this – about 4% better.

Optimum Tilt of Solar Panels

Equation: If your latitude is between 25° and 50°, use the latitude, times 0.76, plus 3.1 degrees.

Solar panel pitch for Budapest (47.4547N, 19.0498E)

Winter: (47.4547 * 0.89) + 24 = 66.2347ᵒ
Summer: (47.4547 * 0.92) – 24.3 = 19.3583ᵒ
Spring/Autumn: (47.4547 * 0.98) – 2.3 = 44.2056ᵒ
Full year (no adjustment): (47.4547 * 0.76) + 3.1 = 39.1656ᵒ

Solar panel pitch for Mezőszentgyörgy (46.9969N 18.2752E)

Winter: (46.9969 * 0.89) + 24 = 65.8272ᵒ
Summer: (46.9969 * 0.92) – 24.3 = 18.9371ᵒ
Spring/Autumn: (46.9969 * 0.98) – 2.3 = 43.757ᵒ
Full year (no adjustment): (46.9969 * 0.76) + 3.1 = 38.8176ᵒ

Tools to assist in sun calculations

Solar panel pitch for Daruszentmiklós (46.8363N, 18.8594E)

Winter: (46.8363 * 0.89) + 24 = 65.6843ᵒ
Summer: (46.8363 * 0.92) – 24.3 = 18.7894ᵒ
Spring/Autumn: (46.8363 * 0.98) – 2.3 = 43.5996ᵒ
Full year (no adjustment): (46.8363 * 0.76) + 3.1 = 38.6956ᵒ

Heat your home using energy from the sun

Radiant floor heat has become increasingly popular and it’s easy to understand why. This type of heating system works by pumping hot water – or water and propylene glycol (antifreeze) – through a system of tubing under the floor. This means houses using this heating system get warmer from the floor up. In the winter there are no cold floors underfoot – instead the floor is the warmest part of the home.

Heat Your Home With Solar Hot Water Read the article

A simple off-grid electricity system

Prepare to evaluate the current system

Buy a multimeter. A £10 – 15 will do.

Check the current system

Check for 10.5 – 15 volts supply from the current system components.

Buy new system components

  1. a 300W DC Inverter,
  2. a 700VA Uninterruptible Power Supply (UPS). This should have it’s own battery,
  3. a 12V DC inline Fuse Holder,
  4. 35 Amp fuse and sufficient 12V cable to connect all components.

Set up the new system

Run the cable from the panels/turbine to the fuse to the inverter+UPS. Connect the multimeter in-line in Amps-mode and connect to the inverter. Plug the Inverter into UPS. Plug all the appliances into the UPS.


  1. Build It Solar
  2. Simple Solar homesteading
  3. Off-Grid Forums
  4. Bright Hub Engineering
  5. Build Green Energy

Using Passive Solar Energy to heat your straw bale home.

Passive Solar Energy

Passive Solar Energy as a free heat source for your straw bale house. Read the article

A rule of thumb for installed window area

East side of the house 4%, west side 2%, north side 4%, and south side 7-12%. So if you had a floor plan of 1000 square feet, on the east side of the house you would allow for a total square footage of 1000 SF x 4% = 40 square feet of glass and so on.

Read more: