In Adelaide in June the average daily solar insolation onto a horizontal plane (i.e. with a tilt angle of zero degrees) is 2.3kWh/sqm.
At different tilt angles, the June daily solar insolation is:
3.3kWh at 20deg, 3.6kWh at 40deg, 3.6kWh at 50deg, 3.6kWh at 60deg, 3.5kWh at 70deg, 3.4kWh at 80deg, 3.3kWh at 90deg.
http://rredc.nrel.gov/solar/calculators/pvwatts/version1/International/inputv1_intl.cgi
The average daily solar insolation for each month is shown in the following Chart:

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The value 3.6kWh/sqm per day for the June solar insolation is used in the following calculations.
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SOLAR PV:
The purchase price for solar PV panels, without rebates, without installation and ? without an inverter is ? $1.50/Watt.
Say ? $2250 for a 1.5kW system with 8 panels of mono-crystalline PV covering 10sqm.
Per sqm this is 2250/10 is $225/sqm.
The amount of electrical energy that is collected from mono-crystalline panels is ~12% of the solar insolation.
The average June daily electricity collection from one sqm of PV panel in Adelaide is
0.12 x 3.6 is 0.43kWh/day per sqm.
If this solar electricity replaces grid-electricity bought for 30cent/kWh it is worth
0.43 x 30 is 13cent/day per sqm
If the PV system is not grid-connected, batteries with capacity to store one daily cycle of 0.43kWh per (sqm of PV) are needed so that the electrical energy can be used at the times and in the locations that it is needed.
If CALB (previously Sky Energy) LiFePO4 batteries are cycled between "Full" at 95% and "Re-fill" at 30% they will last for 3000+ cycles (~8 years at one cycle/day).
http://ev-power.com.au/-Sky-Energy-Batteries-.html
To deliver 0.43kWh/cycle, requires LiFePO4 batteries with a storage capacity of
0.43kWh / (0.95-0.30) is 0.67kWh/(sqm of PV).
At 12Volts this is 670W/12V is 56Amp.hours per (sqm of PV collector)
For Lead Acid batteries, the Chart below shows that using a DOD of 70% the battery life is 780 cycles (about 25% of the 3000+ for LiFePO4).

By choosing Lead-Acid batteries the required storage capacity would exceed 100Ah per (sqm of PV) and the life of the Lead-Acid batteries would be less than half that of LiFePO4 batteries.
Instead of installing an excess capacity of batteries, it is cheaper to use a 2.4kVA (petrol) generator (? $1000) to charge the batteries on each cloudy day or whenever additional electricity is needed.
The cost of LiFePO4 batteries is about $500 per kWh.
At 12V one kWh is 1000Wh/12V is 83Amphour.
In summer the daily return from solar PV is at least double the winter return.
A battery comparison with CALB notated as "SE" is at
http://www.evpower.com.au/IMG/pdf/TSvsSE_comparison.pdf
After investing in a CO2 heat pump (a reverse cycle air-conditioner or a heat-pump hot water system), one kWh of electricity can be used to provide up to 4kWh of solar heat.
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COMPARE SOLAR THERMAL:
A purchase price for solar thermal Evacuated Tube (ET) collector panels, without rebates, without installation and without an insulated tank is $1550 for 30 tubes covering 3.8sqm.
i.e. 1550/3.8 is $408/sqm from
http://www.runonsun.com.au/runonsun/Retrofit_or_complete_split_system.html
Alternatively, for an ET collector area of 3.8sqm with 30 tubes (? different tube quality) and including the frame
the price for supply only is $907 or $238/sqm from
http://www.fxlarkin.com.au/page119775.cfm
In Adelaide, in winter (June) the amount of solar energy collected as heat by ET is ? 70% of the solar insolation.
http://www.energymatters.com.au/renewable-energy/solar-power/solar-hot-water/hills-collector-efficiency.pdf
The typical daily heat collection using ET from one sqm in Adelaide in June is
0.70 x 3.6 is 2.5kWh/day per sqm.
If this heat replaces heat from an electric resistance heater using night-tarrif electricity bought for 14cent/kWh it is worth
2.5 x 14 is 35cent/day per (sqm of ET)
If the heat from the ET collector replaces heat from a CO2 heat pump with COP of 4.0,
http://www.ata.org.au/forums/topic/4384
then the heat is worth 14/4 is 3.5cent/kWh so
2.5 x 3.5 is 9cent/day per (sqm of ET)
An insulated tank is needed to store the solar heat energy so that it can be used when and where it is needed.
One kWh of heat is needed to heat 20litres of water by 40degC, e.g. from 20 to 60degC.
If the water is heated by 40degC, the volume of water that is needed to store 2.5kWh of heat is 2.5 x 20Litres is 50Litres of water.
This suggests needing an insulated tank volume of 50Litres per sqm of ET collector, or 200Litres for a typical 30tube ET system that covers ~4sqm.
The cost for a Chinese insulated stainless steel tank is $2.50 to $3.00 per litre.
An Everlast (made in Victoria) ? 327 litre insulated stainless steel tank including a stainless-steel heat-exchanger tube costs ? $1000.
In summer the additional heat that can be captured by solar thermal typically is wasted unless it can be used to heat a swimming pool.
Other links:
http://www.ata.org.au/forums/topic/3253#post-25940
http://www.ata.org.au/forums/topic/3253#post-26134
http://www.ata.org.au/forums/topic/3253#post-26175
Posted Saturday 15 Jun 2013 @ 11:53:15 pm from IP
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