Photovoltaic (solar power) system
Sixteen BP3165N solar panels are mounted on the roof. Each can generate a maximum of 165 watts, for a total capacity of 2.64Kw peak.
They are attached to a SMA SB2500E inverter in the car port, which converts the direct current output from the panels to normal 240V Ac and synchronises the frequency with the grid. It also takes care of safety issues, and will disconnect from the grid if it does not sense any grid voltage (so we don’t shock linesmen when the grid voltage is turned off).
A new meter was fitted so that Country Energy could measure the power exported as well as our usage, and we payed them for the difference between the two. When the NSW feed in tariff was introduced we needed to install a new cable from the inverter to the meter box, and a different meter was installed. We now are paid 61 cents for all power we generate which means our bill is in credit of over $150 each quarter. We still pay for the fixed daily charge which is about $70.00 per quarter.
The system was designed to generate as much power as we use over the course of a year, but we had a problem with our inverter ever since it was installed. After thinking we had wrongly estimated the amount of power we would generate, we eventually asked the installer to test out the system and he arraigned for a new inverter. This has been generating 20% more power than the old one for the last 4 months, which will definitely cover our usage. Over the last year we have generated 7.6KW hours per day and used 7.3KWHr.
Power generation varies quite a lot, from 13.4 KWhr on a cloudless summer day (with the old inverter), to about 9 KWhr on a clear winter’s day, and almost nothing on a very overcast rainy day (Our lowest reading for a day was 0.18KWHr) . The panels are less efficient when they are hot so the ideal is a long cool cloudless day.
The system was installed by Brian England of Self Sufficiency Supplies (02) 6562 7704 who is highly recommended.
Yes it’s me …. My SMA is down about 20% on projected (ave is 18Kw/day – should be 25ish) … I’ve got 100ms of panels … But orientation / tree shadow is an issue
How hard was it to test the inverter
looks like your having fun
Linden (Sitting at Dickies for another month) ROTH
Its tricky to test the inverter, I was lucky in having a neighbour with the same inverter and panels 1km up the road, so we tested at midday for peak power on a few occasions and corrected for the number of panels – daily figures are just a guide.
Orientation is not a great issue as long as its close (from north to east or west would be about 15-20% loss), but shading is with a single inverter. You would have similar issues to us – we have shading in morning and evening but not during the day and it looses us about 15%.
The only option for persistent shading is to drive the panels independently or in smaller groups, either by putting on panel level inverters or by using separate MPP (Maximum power point) trackers. Both are expensive after the fact.
Hope this helps.