We recently invested in a basic 1500WPV array on our roof in Victoria, Australia. Due to generous rebates and a premium feed-in tariff (basically middle class welfare) we had a 1.5kw grid connected array installed on our roof for $2900 (AND it was 5% down, 12 monthly payments interest free, FREE money).
It seems to be working out as a good investment.
From my spreadsheet :
Meter Read 08/09/2011 (roughly one billing cycle)
Total Generated 348 kwh
Exported 123 kwh
Consumed 225 kwh
Peak Tariff c/kwh 26.367 $59.32575 (this is saving because of what we did not buy from the grid)
Off Peak Tariff 15.763 (sun doesn’t shine when OP rate applies)
Premium FIT c/kwh 66c $81.18
Total Credit $140
This is the actual reading off the meter :
03 Imported Total 723
04 Imported Peak 476
05 ??? 2
06 Imported Off Peak 247
13 Exported Total 123
14 Exported Peak 82
16 Exported Off Peak 41
Total Consumed 948 kwh
Old Tariff 22.869 c/kwh
Old Cost $216
New Cost $83
Net saving $133
There is a slight difference between the top ‘Total Credit’ figure and the ‘Net Saving’. I put this down to discrepancy (or efficiency losses) between what the inverter reports and what is metered. Probably worth keeping an eye on though as it could be a skim by the distributor.
So we are saving $133 on this quarterly bill, and this is winter, it will be more during the sun months. The depreciation on the plant is estimated at 5% so about $150 per year. I extrapolate that we will generate only 1.5 times the winter rate so lets say we will save $200 in the spring/summer quarters.
By my calcs the return on investment is about net $666, subtract depreciation and we are around $400. So conservatively, about 13.8% return on investment. This will only improve as energy prices rise.