The difference Solar tracking makes

JKenH

On Monday  (26 June) I conducted an experiment with a 370w JA Solar panel which I mounted to a pallet on casters so I could move the panel about and catch the best of the sun. I should point out that the panel is at at ground level in my garden so I do have to move the panel a lot to avoid shadows from trees and roofs and being so low I miss the very early and late sun that my roof mounted panels (particularly the West roof) can catch. While my roofs can see the sun from around 5am to after 8.30pm my pallet mounted panels really can’t see any useful sun before 6 am or after 8pm. I monitored the output with the Ecoflow app.

Anyway, enough preamble, here’s the result - 2.99 kWh from 7.8 0.37kWp (just over 8 Os*). For comparison, on a day that favoured them, my East and West roof mounted systems both reported 4.5 Os (from the Solarman app) after a very sunny morning (until 10.30) and a sunny afternoon/evening from 4pm. In between we saw some sun and a lot of cloud. A nearby SSE system (around 100m) away that reports on SolarEdge recorded 5.3 Os the same day. 

If you are able to move your panels (both orientation and inclination) to follow the sun there is easily the potential on a great summers day to achieve 9 Os and maybe 10 Os might be possible? 

*In case you are unaware Os are a measure used on the talking ‘bout my generation thread to represent kWh generated/size of installed system in kW (kWp).

Grandad2b

At a commercial level I see the attraction especially on sunny days. There would be significant downsides however: increased cost and complexity, risk of damage from wind to name just two.

EricMears

JKenH said:

On Monday  (26 June) I conducted an experiment with a 370w JA Solar panel which I mounted to a pallet on casters so I could move the panel about and catch the best of the sun. I should point out that the panel is at at ground level in my garden so I do have to move the panel a lot to avoid shadows from trees and roofs and being so low I miss the very early and late sun that my roof mounted panels (particularly the West roof) can catch. While my roofs can see the sun from around 5am to after 8.30pm my pallet mounted panels really can’t see any useful sun before 6 am or after 8pm. I monitored the output with the Ecoflow app.

Anyway, enough preamble, here’s the result - 2.99 kWh from 7.8kWp (just over 8 Os*). For comparison, on a day that favoured them, my East and West roof mounted systems both reported 4.5 Os (from the Solarman app) after a very sunny morning (until 10.30) and a sunny afternoon/evening from 4pm. In between we saw some sun and a lot of cloud. A nearby SSE system (around 100m) away that reports on SolarEdge recorded 5.3 Os the same day. 

If you are able to move your panels (both orientation and inclination) to follow the sun there is easily the potential on a great summers day to achieve 9 Os and maybe 10 Os might be possible? 

*In case you are unaware Os are a measure used on the talking ‘bout my generation thread to represent kWh generated/size of installed system in kW (kWp).

Surely "2.99 kWh from 7.8kWp (just over 8 Os*)"   can't be correct ?

Using Oscar's formula,  I'd call that 0.38 O's   !

Most likely typo is that generation was actually 62.99kWh

JKenH

EricMears said:

JKenH said:

On Monday  (26 June) I conducted an experiment with a 370w JA Solar panel which I mounted to a pallet on casters so I could move the panel about and catch the best of the sun. I should point out that the panel is at at ground level in my garden so I do have to move the panel a lot to avoid shadows from trees and roofs and being so low I miss the very early and late sun that my roof mounted panels (particularly the West roof) can catch. While my roofs can see the sun from around 5am to after 8.30pm my pallet mounted panels really can’t see any useful sun before 6 am or after 8pm. I monitored the output with the Ecoflow app.

Anyway, enough preamble, here’s the result - 2.99 kWh from 7.8kWp (just over 8 Os*). For comparison, on a day that favoured them, my East and West roof mounted systems both reported 4.5 Os (from the Solarman app) after a very sunny morning (until 10.30) and a sunny afternoon/evening from 4pm. In between we saw some sun and a lot of cloud. A nearby SSE system (around 100m) away that reports on SolarEdge recorded 5.3 Os the same day. 

If you are able to move your panels (both orientation and inclination) to follow the sun there is easily the potential on a great summers day to achieve 9 Os and maybe 10 Os might be possible? 

*In case you are unaware Os are a measure used on the talking ‘bout my generation thread to represent kWh generated/size of installed system in kW (kWp).

Surely "2.99 kWh from 7.8kWp (just over 8 Os*)"   can't be correct ?

Using Oscar's formula,  I'd call that 0.38 O's   !

Most likely typo is that generation was actually 62.99kWh

Well spotted Eric, it should have read 2.99 kWh from 0.37 kWp. I’ve corrected the original post. Thanks.  

michaels

Ideally if you had a few of the same panels and did tracking with some and not the others as the roof panels may just be less efficient despite their rating and obviously using the same panel but on different days is not a fair test either.

What I find interesting is that commercial panels seem to be orientated south to maximise output rather than maximising the value of output (more west facing) as the drop in production would generally be more than offset by the increased value of the output.  May link to the CfD mechanism?

ispookie666

Very nice. 
I love how the SolarFlower looks, shame it's so expensive 

ABrass

Don't forget the thermal efficiency difference, ground mount is generally cooler and has significantly higher efficiency. To control properly you'd need a similarly mounted second panel.

Magnitio

Quite a good article on tracking here:

https://www.spiritenergy.co.uk/kb-pv-solar-trackers

Martyn1981

Magnitio said:

Quite a good article on tracking here:

https://www.spiritenergy.co.uk/kb-pv-solar-trackers

That's a great article.

Back in 2011/12, I followed the build of a dual tracker PV system by one of the members of the Navitron forum (now defunct). He showed the whole build process, including the massive concrete pour for the base to hold the main post for the tracker.

I'm pretty sure his estimate of gain was about 30%, so that fits well with the article. And the main benefit was the uplift in the winter when a fixed system would not be at a steep enough angle. But as per the article he did have to maintain the various mechanisms, and also make sure the panels were in a horizontal position for storms.

The off-grid guys seemed particularly interested at the time, and followed progress.

But, once the cost of panels fell rapidly, the idea mostly lost interest. If you want the extra 20% v's a single tracker, then far cheaper and easier to install 20% more PV, and to get the winter uplift, install the whole array at a steeper, winter optimised pitch, since there'll be enough gen in the summer anyway, and if you add 20% more PV, then that will make up for the steep pitch 'loss' during the summer.

For off-grid at the time, and now more and more so on-grid, the other issue was batts. If you have them, then time of day generation doesn't matter as much, so a capacity boost 'solves' the problem.

Of course for large scale arrays, especially those at lower latitudes, then a simple single axis tracker that slowly rotates the panels from east to west during the day seems to be worth it. The US southern states can get almost 30% capacity factor with single axis tracking, v's about 11% to 12% for UK fixed PV mount.

JKenH

I quite agree. With panels as cheap as they are, just adding more panels is the best option, unless you are limited by practical considerations. Needless to say, I am thing of buying more! 

If like me though you enjoy having a bit of fun with the panels having then you can maximise the value of a single panel. The other problem that I have is, just so many trees, that at ground level there is nowhere that would catch the sun all day. 

I need to be able to move the panels so while doing so I can turn them at the same time. I am sure I will get bored with that but it gets me some exercise. The panels will get put in the garage in stormy weather. 

My solution of a pallet mounted on casters (recycled - my Halfords tool chest now stands on blocks of wood) was relatively cheap requiring only a set of Ecoworthy mounting brackets (£27 approx). The Ecoworthy frame does allow easy adjustment of elevation as you just move the meeting point of two frame sections to a different hole.

The 370w panel which I collected locally cost me £110 on eBay plus £3 or so for fuel so I wasn’t going to go over the top on hardware to mount it.