Sunday, 4 November 2012

Home-made Solar Panels - Part 2 - Operational Data, Costs & Economics

This is the promised second part of the Solar Panels post.  In this, we'll take a look at Operational Data, Costs & Economics.

Operational Data

The first panel was commissioned on 03 May and the fifth on 20 June.  Operational data was collected on a daily basis from the time the first panel was in place, and so at the time of writing we've exactly six months' worth of data. 

This summer has been very much a mixed bag in terms of weather - May wasn't too bad, June was very poor and the beginning of July only a little better, but since then it's been more typical of what we can generally expect around here.

Graph 1 below shows the total cumulative energy from the array since the time of hooking up the first panel.  The curve starts off rather shallowly and then gradually steepens as more panels become live, but the gradient is not as high as expected since the weather worsened through the commissioning period.  

Note that all of these graphs shown here represent net AC energy provided to the house grid, i.e. all the losses and inefficiencies in the grid-tie inverter during rectification and transformation from DC to 240V AC are already accounted for.  The light red line on the graph is a linear trend line.

Graph 1

(click on any of the figures for a larger image)