So, after 12 months, what do the numbers say?

Well first a quick reminder of what I have running. A Steca Grid 300 from mysolarshop.co.uk, fed from two Evergreen ES-180RL 180 watt PV panels on the roof of the shed.  They are fairly flat on the shed and not in an ideal location. There is about 5-10 degree of tilt on the panels.  One of them is ‘facing’ South East, the other North West. So a very non-ideal situation, but useful nonetheless.

I’m using rrtdool to graph the output from an Envi CC128. The CC128 is measuring the output of the Steca grid-tie inverter.

So for the last 12 months rrdtool is saying an ‘average’ of 35 watts is produced every day. So from the back-of-an-envelope, we get 0.035*24*365 or approximately 306 kWh produced, with a value of approximately €55. Not a whole lot really.

Looking at the ‘average’ consumed by the house. It is now showing as 391 Watts (down from 455 the last time I looked). Giving 0.391 *24*365 or approximately 3425kWh (approx €620).

In short, its knocking about 10% off the electricty bill at present, not a lot, but given the panels don’t receive any direct sunlight in mid winter, it isn’t bad at all.

The experiment continues.