# The Naked Scientists Forum

### Author Topic: What is the optimum angle for a solar panel?  (Read 6907 times)

#### turnipsock

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##### What is the optimum angle for a solar panel?
« on: 15/07/2009 00:38:55 »
I have noticed the way that the council put up solar panels nilly willy. They seem to just point them at the sun when they put them up.

However, there must be an optimal angle to get the most out of them. I live at 56 degrees north, but if I positioned my mole deterent at 34 degrees then it would only be most efficent at mid day.

There are a huge number of factors to consider...seasonal things, thickness of the atmosphere when the sun is round to the west, the fact that sun might go behind the solar panel.

being delivered next Tuesday.

How do you calculate the best angle?

#### LeeE

• Neilep Level Member
• Posts: 3382
##### What is the optimum angle for a solar panel?
« Reply #1 on: 15/07/2009 22:12:29 »
You need to decide for what period, throughout the year, you want to optimise the output.

You'll only get maximum output by pointing it towards the sun when it's at its zenith on the longest day of the year, as that's when the sun will be at its highest in the sky and the light will be passing through the least amount of atmosphere, but this will mean sub-optimum output for all other times i.e it will be less efficient when there's less light available.

For a more balanced output over a longer period of time, and assuming an uninterrupted horizon, you should still aim the panel in the direction of the zenith but as for elevation, well, I'd be inclined to aim for the zenith a week or three after the spring equinox, which will also correspond to the similar period before the autumnal equinox.  This way you should get better output when the sun is lower in the sky but still get good results when it's higher in the sky.

You could work it all out if you want but I think it's probably more effort than it's worth.

#### techmind

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##### What is the optimum angle for a solar panel?
« Reply #2 on: 15/07/2009 23:15:39 »
It will depend partly on whether you want to maximise the total energy received over the year, or whether there's a minimum amount of energy you must receive every week (or whenever) through the winter.

In azimuth, I expect it's best to point due south (unless there's reason to believe that the cloud cover favours morning over evening or vice-versa).

In elevation, something pointing nearer the horizon will be best in the winter - maybe 30 degrees above the horizon, while the summer optimum will be higher in the sky (and will then also make better use of the greater number of hours of daylight).

#### lyner

• Guest
##### What is the optimum angle for a solar panel?
« Reply #3 on: 15/07/2009 23:39:18 »
Does anyone make a steerable one?

#### tommcb99

• First timers
• Posts: 1
##### What is the optimum angle for a solar panel?
« Reply #4 on: 08/09/2009 01:25:16 »
Hmmmm - a steerable solar panel - now that's a creative idea!

Problem is, the number and size of solar panels needed to supply a substantial amount of the average home's power probably prohibits any sort of a device that would adjust them to the best advantage throughout the year.

However, this is still an intriguing idea and I'm going to bounce it off some engineering types I know to see if it's even feasible to consider for a house.

Best regards,

Tom

#### lyner

• Guest
##### What is the optimum angle for a solar panel?
« Reply #5 on: 08/09/2009 10:42:40 »
It strikes me that all this equipment could be supplied at a fraction of the present cost. Once the manufacturers realise that they have more potential business from a mass market than from selling prestige installations then the development and  production can really take off. By the third generation, they will be working much better and costing much less. It won't happen whilst there's so little competition.

#### LeeE

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• Posts: 3382
##### What is the optimum angle for a solar panel?
« Reply #6 on: 08/09/2009 15:33:25 »
Regarding steerable solar panels, you would, of course, have to balance the trade-off between energy lost due to not working at an optimal orientation against the energy cost of detecting and maintaining the optimal orientation.  You might find that a steerable panel uses more energy than you gain by making it steerable.

If there are benefits to be gained, you'd then have to work out the equipment cost effectiveness of the solution too, so in addition to weighing the energy cost of actually steering the panels against the extra energy gained, you'd also have to work out how long would it take to offset the energy cost of making the detection and steering equipment in the first place.

#### lyner

• Guest
##### What is the optimum angle for a solar panel?
« Reply #7 on: 08/09/2009 17:06:59 »
I had an idea that some steering could be achieved using a (passive) arrangement of  'bladders' or cylinders on either side of a vane which would inflate differentially, when warmed, according to the angle of arrival of the radiation and the shadow of the vane on each side - the appropriate sign of the feedback signal would keep the arrangement facing in an optimum direction.

This system might not help a lot with simple black absorber systems but those with back reflectors and heat exchangers which operate at high temperatures would probably benefit greatly from good alignment. These advanced systems are particularly good for producing small quantities of very hot water rather than large quantities of just warm - particularly on winter days mornings or afternoons. (On the burning glass principle)

But of course, the cost benefit is what counts. You need to do the sums for each case.

#### The Naked Scientists Forum

##### What is the optimum angle for a solar panel?
« Reply #7 on: 08/09/2009 17:06:59 »