Solar Trackers.

[clockmanFRA]

A big thank you to this forum for giving me information to help design and build my Trackers.

Each tracker can take up to 8 panels, 1 meter by 1.6 meter (2kw) but i have fitted just 1.5kw.

Normally, I am a Hugh Piggott Wind Turbine maker (3off 3.7m 12 footers) but the cost of materials has now reached a point where its more cost effective to make 1.5kw trackers, and off course the added bonus of less moving parts.

My panels are Sharp seconds, ie they were rejected becuase of minor fualts, cost 3Kw at £1700 GBP, metal, actuators and electronics etc £1200 GBP. Total, with MPPT controller, about £3300 GBP for 3Kw of electricity production.

Pic 1,  No 1 tracker complete, noon position and positioned for max summer angle. No2 Tracker has scaffolding around it and is in storm position awaiting its panels.

Pic 2,  Shows the actuator and winding handle for the seasonal angle adjustment.

My Mrs has posted this DIY Budget project on her, (she does all the talking, i just do the work  ) Website,

http://www.echorenovate.com/   

       We are not a comercial enterprise but just trying to spread the word.

[Bruce S]

NICE!!
I like the pic of the scaffolding , it helps with the scale of those tracker units!
Other website is nice too, the Cider making post was fun to read. 
AND thanks for updating us on your progress.
Cheers;
Bruce S

[MarkMac]

That's a really nice project ClockmanFRA, but I'm a little bit worried about your array size. I hope you don't mind my input.

Pardon the lack of a specific link, but I was browsing about on this site for solar tracker information and saw one picture of the twisted metal and ruined panels remaining from a pole tracker after a bad thunderstorm. That guy vowed never to use a pole mounted array again, though I wouldn't go that far: it just needs to be engineered for the load. I don't know what kind of winds you get, but wind speeds of 95mph  ( ~150km/hr) have about 25lb/ft2 (122kg/m2) of pressure (typical max/25 year  wind load in many areas). Since you have wind turbines, I'm guessing that you have a fair amount of wind, and perhaps you've already taken this into consideration. I certaily approve of the gussets on your poles. My calculations show that the potential wind load comes to about 2800lbs (1270kg) for your array size. Even halving that number is still a lot of force. Remember that the linear acuator is at a leverage disadvantage and a strong gust hitting the array in an uneven fashion could apply a huge amount of force causing it to fail and your array to then flail in the wind and potential self destruct.
Your poles look pretty tall, and at 800mm deep your foundations may well fail even if the rest of your mount doesn't. It only takes one bad storm!
I'd love to hear from anyone regarding how to calculate wind load for a pole mounted array. Obviously there are a lot of variables and various components with different stress levels. Here's a crude equation I've come up with for the linear actuator load:
   1/2 x TotalPanelArea x maxWindPressure x (0.25 x ArrayWidth)/controlArmLength = maxActuatorLoad
This equation assumes that a gust hits half of the panel, creating maximum torque about the axis of rotation, and this load is then effectively centered in the middle of that side (the 1/4'th width factor), which determines the leverage against the actuator depening on the control arm length. Starting with a known maximum actuator load and control arm length, this can be solved such that maximum TotalPanel area is a function of the width.

Cheers,
Mark

[Mary B]

The older 36 volt satellite actuators for 10+ foot dishes will take a huge static load. Actuating force is usually in the 2,000 pound area. Storm tie downs on all 4 corners would be a good idea.

[clockmanFRA]

MarkMac,

Yes, I have considered the wind loadings, and have already tested No 1 Tracker in 50mph winds last week, I left the tracker in noon position for summer angle. And it shook a bit and moved around but the frame did very well.

However, if I get information (weather forecast  about bad storms then as I mentioned I can make the whole panel area lay flat/horizontal (storm position) and put rope/straps on to lock it down.

The panel rails are solid box section and the panels are bolted down with 1/4 inch thick ally brackets.

The main mount pole is 6 inches diameter and is 3/8 inch thick wall, the struts are 2 x 2inch angle at 1/4 inch thick.

The actuators are really good, will lift me, 90Kg, swinging on the tracker panel corner, but the swivel joint at the top is a bad design and I have had to weld the bushes in.
   
Pic of design drawing shows radius for the actuator, but this was to much loading, and i have now increased the radius to 400mm.

Total weight of my trackers above ground is about 245Kg, about a 1/4 of a ton.
   

[clockmanFRA]

Here's a few pics of the actuators.

Pic 1,
Pic 2, The grey one is a normal/standard satellite type i have put along side mine.
Pic 3,  The Actuator top ball swivel joint,   just held in position with a brass conical bush, and it soon worked loose.
Pic 4,  Welded the surrounding cast steel so it formed over the brass bush and now holds it permently in, and joint works well.
Pic 5,  Actuator back in action with a bit of black Hammerite paint to keep the rust at bay. 

[clockmanFRA]

FINISHED.

The NEW Design of SOLAR TRAKERS are now finished and working.

The Electronics units from Dave in Australia are working fine, but have taken time to get used to the fast moving clouds, but the tracker does not spend all its time wasting my precious energy hunting for the pin prick of Sun. And when it's dark, the tracker parks in the East ready for the morning.
I ordered 2 units from Dave, 1 finished and boxed and one kit, (just PCB and bits)…. Total about 130GBP.
http://www.ebay.co.uk/itm/ws/eBayISAPI.dll?ViewItem&item=200731822513&ssPageName=ADME:L:COSI:GB:1123     and….
http://www.ebay.co.uk/itm/ws/eBayISAPI.dll?ViewItem&item=200714107067&ssPageName=ADME:L:COSI:GB:1123    or contact Dave at dave@campatracka.com
or ..David Harvey, 90 Young Road, Cowra, NSW 2794 Australia.

Actuators. I used the 24v versions and I am operating the 36v Actuators with 24 volts, max drain 1.6 amps.     As I said the Actuators, “Genuine Jaeger Heavy duty 24-inch actuator. QARL-3624+”, came from …..248GBP for 2. http://www.satellitesuperstore.co.uk/satellite_diseqc_motors_36_volt_motors.htm#24inchh    But, and a Big But, you will need to modify/weld the top arm swivel joint, or it will just fall out.

Some details: -     Total weight above ground for each tracker, fully loaded up, is about 245Kg.

All I have to do is now upgrade my power management, and sort out the extra dumping arrangements. It is windy and sunny, my 900ah batteries are topping up, the wind turbines are putting 3 Kw in, and the tracker is putting 3.2Kw in, my 3.7kw inverter is loaded, (under floor heating) but I only have 4kw of dumping available,,,,, whoops! 

Last Modification. The actuator top clamp, it bolts to the frame, (done because I was unsure where the optimum radius position would be), could now be a welded strut if using 24inch actuators, giving a 400mm radius to the hinge joint, in the Pic below I have had to put 2x 6mm stainless bolts tapped through both bits of steel, as the clamp would slowly move about.

Pic 1 .., Trackers at morning East position and my 5 year old. Sunday 17th June 2012, (Fathers Day in France).
Pic 2…Tracker switch box No 1.
Pic 3…Tracker switch box No 2. with Dave's boxed circuit inside, yes I know it's not straight but it was the only way to bolt it to my DIN rail.
Pic 4…The 2 off 6mm bolts, modification to the actuator top clamp bracket.

For those of you with fast speed, try this Vid, Its the Mrs with guest appearance about half way.....http://www.youtube.com/watch?v=cEu1W_58Sa8&feature=youtube_gdata_player