Solar Power – No North Facing Roof
Conventional wisdom has been that you needed a North facing roof to mount your solar panels . . . . . . but it might be time to re-think!
Cost of Panels
In the early 1990 when people first really started looking at solar power for the home the cost of pv panel alone was in the order of $7-8/watt and installation efficiency was very important.
Now with panels costing less than $1/watt, installed, adding a few extra panels isn’t as big an issue as it used to be.
The efficiency drop off from moving away from a North facing roof is not as much as you might think.
For instance panels on a roof facing either East or West can still produce more than 80% of the power of a North facing panel. (see Solar Alignment for more information)
More Effective Spread Of Power
A few years ago we were paid for every watt we put into the grid, at more than it cost to buy a watt from the grid. This meant that systems that produced lots of power when we weren’t using that power (typically around noon) had real advantages.
For new systems you are now typically paid less for every watt you produce than a watt costs to buy. It therefore makes sense to be generating power when you need it across the whole day so you use as much of the solar power yourself.
A couple of options are:
- Split the panels evenly between say Westerly and Easterly facing it you are looking for an even spread of power across the day.
- Concentrate on westerly facing if your main power use is in the afternoon and evening.
A Few Final Points
- Although this post has been mainly written for grid based systems there will be some benefits for more even power generation for stand alone systems, as it could reduce the battery discharge cycles,
- In the past, to maximise efficiency, systems were built with mechanical trackers to follow the sun. With the current low cost of panels I don’t think trackers can be justified due to cost and increased complexity.