Solar Power

 
Solar panel array from RPC manual (photo by RPC 2006) 
http://www.rpc.com.au/catalog/bookenergyfromnature140pcd3000pages-p-981.html .

Solar power has the potential to reduce CO² emmissions and reduce the amount of greenhouse effect on the earth. Development is ongoing in the equipment needed to create and store electricity from solar energy. Solar panels have gone from generating 20-40watts of power to creating 130watts over the last few years. The significance of solar power is that it has minimal interference on the environment of the earth.

Electricity is a complex topic but below are some simple ways to think about electricity. Consider electricity like water to understand the terminology¹:

Current (rate of flow of electricity)
If a water pipe is securely stopped at the end there is still pressure in the pipe. This pressure in the pipe is similar to the current in an electrical wire and only flows when circuit is completed in a similar way to the water tap only works when the tap is opened to allow the water to flow through. Something creating power like a solar panel or generator is like a water pump. The pressure created in the circuit is called voltage. The higher the volts the stronger the current of electricity.

Electrical Storage (batteries)
It is necessary to store power generated by solar panels because the sun doesn't shine at night. If power could be generated all the time then no batteries would be required. (So a diesel generator or a wind turbine will work at night and less or no batteries are required for this type of system.)  A higher voltage is required than the voltage of the battery so that electricity will flow into it in a similar way that water needs to be higher than the outlet to create a water flow. So 15 volts or higher of power is needed to charge a 12 volt battery.

Flow Rate (amps)
Even with good panels and a large number of panels the amount of charge in the batteries is effected by the wiring and connections to the batteries. In a similar way if there are leaks in pipes or inadequately sized pipes in a water system all of the water supplying the water tank doesn't get through. The amount of electricity than can pass along a wire is measured in amps.

The Formula
To work out the relationship of the rate of how much electricity can flow into the storage(watts) there are 2 variables, the current (volts) and the flow of the cable (amps). So rate of flow equals the pressure times the diameter of the outlet, or W=V x A. (Watts = Volts multiplied by Amps) Therefore the amount of watts can be increased by increasing the current and/or increasing the flow of the cable.

Battery Charge (amp-hours)
Power flow multiplied by time charged = Number of amp hours
Eg, One amp charging for 100 hours = 100 amp hours, or,
10 amps charging for 10 hours = 100 amp hours.
For the example of an electrical appliance that uses 10 amps and it is left on for for 10 hours then 100 amp-hours have been taken out of the electrical storage system (battery).

Battery capacity is usually rated in amp-hours. The amount of charge left in a battery is determined by the amount of charge in amp-hours minus the amount of discharge in amp-hours.

A common measure of power is watt-hours. Watt-hours = amp-hours x volts.

Batteries are developing all the time but still need considerable increase in capacity. One way to overcome this is to have the battery in the device attached to the solar power source. Similar to electric razors, electric toothbrushes. mobile phones, electric cars, etc which all have their own batteries. There is scope in the authors opinion to develop batteries for use by all our commonly used appliances which directly store energy from solar power.

Estimating Power Needs

Check out the appliances ratings for the amps and voltage needs. Multiply the amps by the anticipated hours of use and add up all of the appliances needs. Also if appliances need to run at 240 volts then there is an 85% efficiency rating (energy is lost) in the power inverter.

Example (12 volt system)

Note: Watts and voltage may vary depending upon the appliance used. Efficiency of inverters and any system also requires checking. The hours each appliance is used also depends upon personal preferences and demands. This table is an example only. The above table is also working on 2 types of wiring, ie 12volt and 240volt (with an inverter). For a larger list of wattage and different appliances check the rating on the individual appliance on the compliance plate or stamp or check RPC's lists at http://www.rpc.com.au/products/efn/efnextracts/estima_rating.html .

Some examples of panels are 12x200watts of panels which will supply 2400watts of power of 200 amps and supply about 1000 amp-hours per day (northern NSW). So in the above example this would run the dishwasher but with everything else turned off. Dishwashing could be done in the day or a bigger system installed. The notebook computer, some lights, TV and CD player plus other appliances could all work at once in the above example. A quote for this type of system, supply only, with inverter, mounting brackets, wiring supply only, batteries, regulator, etc in 2006 was $A30000 plus GST. Installation was extra to this cost. It may seem expensive but considering the concrete in a house would probably cost more than this and give no financial benefit during the life of the building then it is cheap. The resale of a property with alternative power sources could also be higher than conventional power systems. The saving of CO² emmissions is considerable and greatly reduces the warming of our planet.

Some appliances can run on other alternative power services, eg, a refrigerator and stove can run on gas which is still low cost. 

Sell Back to the Electrical Grid

There is also the option of selling back to the electrical grid. I enclosed some examples from RPC of costs to install electrical supply systems which sell electricity to the power grid. Grid option current in 2006 (Australia). Again the returns are not high but higher than other building components including concrete, timber, roofing, etc which pay back nothing during the time a building is owned and occupied. Greenhouse gases are again reduced.

The Future

Scientists are considering the way plants store and use solar energy to see if this can be used to store energy for our solar systems. Solar panels, batteries, etc are increasing in efficiency all the time and have minimal effect on earth.

Reference 1, Peter Pedals, Energy From Nature, self published, http://www.rpc.com.au/catalog/bookenergyfromnature140pcd3000pages-p-981.html .

Electric Barbecues

The Greenplate electric barbecue can be connected to a solar array or mains power and is an option to reduce greenhouse gases. Please refer to http://www.cosmossolar.com.au/mains-electric/products.php .

Angle For Solar Panels

The optimum angle for tilting solar panels is the lattitude of the building, facing north or south (facing the sun depending upon whether northern or southern hemisphere), +15 degrees in winter and -10 degrees in summer. Please see http://www.yourhome.gov.au/technical/fs67.html.