East/West Arrays and adjustable AZ

[jsmetalcraft]

I have been studying about east/west facing arrays. For me I have settled that an Eastern array would be advantageous, ground mount. In running the simulations it appears that having them on an adjustable AZ may be beneficial. Initial thoughts were to go 45* each side of 180 (135 for East and 225 for West). But there seems to be some gain by adjusting the Western array between Winter and Summer.

I will build my own mount so the cost would be reasonable. Any thoughts as to worth while trying to collect more of the late Summer sun?

 

[45North]

I have been studying about east/west facing arrays. For me I have settled that an Eastern array would be advantageous, ground mount. In running the simulations it appears that having them on an adjustable AZ may be beneficial. Initial thoughts were to go 45* each side of 180 (135 for East and 225 for West). But there seems to be some gain by adjusting the Western array between Winter and Summer.

I will build my own mount so the cost would be reasonable. Any thoughts as to worth while trying to collect more of the late Summer sun?

Make it adjustable.
Then you can set and tweak it any way you want.

 

[MichaelK]

Feel free to copy mine. I would be honored.

 

[jsmetalcraft]

Feel free to copy mine. I would be honored.

Nice work. I built one similar to yours with four 300w panels. It was more on the temporary side, so I did not add the extra braces. When the wind blows it flexes quit a bit. The new array will be 8 - 435w panels so the structure will have to be much heavier. Just picked up several 31' lengths of 2-7/8" well stems. Post will be 8" I beam.

 

[MichaelK]

I'm especially proud of the two inner braces. If you look at the back of the frame, the two outer braces are welded directly to the frame. The two inner braces however are cantilevered over the hinge area. They were designed to be bolted into place after the frame was assembled.

The whole array frame is basically divided into two halves. The lower T-portion sits on the 3.5" pipe sunk in concrete. The rectangular solar attachment frame half then gets bolted onto the T-portion. Then the cantilevered trusses go on last. This makes the array installation a two-man job instead of a three man job.

Here are some pics of my first generation design (V1.4), holding three 300W panels. It took three of us to fit this in place to drop onto the 3.5" concrete sunk pipe. This could also be adapted to the modular two piece design, but I hadn't yet thought of that.

 

[Hedges]

Single post looks clean, but I'm a believer in triangles.

My first arrays were pole top, intended to have 6" pipe set in a huge concrete footing.
I acquired some 4" pipe, which I welded to a plate and bolted to existing concrete (therefore not a very rigid connection.)
With two diagonal braces it was plenty rigid.

 

[Ampster]

Any thoughts as to worth while trying to collect more of the late Summer sun?

Depending on your NEM agreement and rate plan, west facing arrays can generate more dollars. You will not generate more energy versus a south facing array. However the ratio of the DC capacity of the panels to the AC capacity of the inverter can make a difference when using arrays facing east and west.

 

[MichaelK]

Single post looks clean, but I'm a believer in triangles.

That's how I did my V2.0 design. I basically made that a three-dimensional triangle. I have that array frame sitting on my workshop roof. Sorry, I don't have any pictures of that one. Should get around to that.

I too am a believer in triangles. If you look at all my frames, there reinforcing trusses in all dimensions. I started out by copying what I saw of the design of overhead highway sign frames, the ones that reach completely across the highway lanes.

My very, very first solar frames were made out of sheetrock edging. Seems like the most rinky-dink material to build a frame out of, but by spacing triangles every 8-10", it became very sturdy.

 

[Hedges]

Depending on your NEM agreement and rate plan, west facing arrays can generate more dollars.

Depending. Used to be my peak rates were Noon to 6:00 PM, so higher value for power in afternoon meant slightly reduced output from SW facing array was outweighed by much higher price per kWh. I aimed them at 2:00 PM sun as an approximate optimization.

My current 4:00 PM to 9:00 PM peak hours probably negate the benefit, and due South would be just as good.
With lots of extra panels I aimed some West or West South West (and a steeper angle for sun lower in the sky.)

Panels are much cheaper now, so I suggest over-paneling with SW and SE facing arrays. Possibly on their own MPPT input, possibly paralleled into a single MPPT input.

 

[jsmetalcraft]

Depending on your NEM agreement and rate plan, west facing arrays can generate more dollars. You will not generate more energy versus a south facing array. However the ratio of the DC capacity of the panels to the AC capacity of the inverter can make a difference when using arrays facing east and west

My system is strictly self consumption without any agreements or plans. I think I have more panels then needed to cover my planned use. After reading about the benefits of west/east oriented arrays and running the numbers I feel it is well worth it, especially for the west facing array. My high use months are July and August due to AC.

Anything over 225* in winter reduces the rate of return. But to get longer into the evening during summer it would be even more advantageous to face at least 247.5* or even 270* . This is why I was thinking an adjustable AZ mount and the bit extra to implement it is showing to be well worth it.

I may add that my higher usage seems to be 10am to 5pm right now. Just started to monitor usage and have not gone back through the power company charts to get a feel for all year.

 

[Wellbuilt]

East/ west configuration is area specific.
In my area NY my sun is very low in the sky this time of year .
So in the am and pm I get very little sun all my charging really takes place between 1030 and 100 the after noon brings clouds and snow most days The good news is the sun gets up into the sky a bit more around the 15th of February
Then there is the snow and ice ?

 

[Ampster]

There is a big advantage of East west arrays with a high DC to AC ratio. Instead of a sinusoidal generation curve you can achieve more production in the morning from the SE array and when that tapers off the SW array ramps up. Instead of just a peak at Noon with a single South facing array the area under the curve is greater. With the cost of panels being less expensive that strategy can have big benefits.
I am on a NEM plan that limits my output to 7.6kW. My array faces SE because of the orientation of my house. I am adding more panels facing SW on a barn.

I am grid tied but use batteries to self consume as much solar as I can. I still need the grid as backup because of differences between winter generation and summer generation. My earlier comment was not meant to disagree with the concept but merely to add context. Adjustable tilt will add to production . I wish I had that option.

 

[Ampster]

Then there is the snow and ice

Another advantage of ground mount variable tilt is the easier removal of snow. With a steeper tilt in winter, gravity can be your friend.

 

[Don B. Cilly]

From what I read (half an hour of groogling around - and getting quite confused) it seems that angle is not all that important.
Once you get some... 30° on them, from there to 90° the difference seems to be in the single-figure percentage.
This is probably more true of newer, more efficient panels... now I may be quite wrong here, but my real-life observations seem to quite agree.

If anyone has some real experimental data on this, I'd be very interested to see it.