I am putting up 3 adjustable angle ground mount arrays, each with 10 400 watt bifacial panels, I am in Michigan. I am putting the 3 all side by side to each other. I am wondering if it is beneficial to put one aiming more SE, center one straight south and the other one facing more SW? I will have ~24k watts of panels total, the other ~12k worth on rooftops facing straight south and 130KW hours of battery storage.
Ground Mount Panel direction question, 3 Arrays.
- Thread starter doox00
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OzSolar
Whatever you did, that's what you planned.
I was chatting about this with a very smart friend the other day.
All of it facing due south gets you the most "potential" daily kWh but it may not get you the most "usable" daily kWh is what we came up with.
I think one needs to try to dig deep into thier system design to better answer this. For example, some solar farms are built facing to the west knowing that when the grid really needs thier energy is from 1PM until things start to cool off at sunset.
Our thinking was that having arrays of different orientations would allow you have a smaller battery bank. PV is cheaper than batteries plus it doesn't take up room inside your house or shop. 2X more batteries cost 2X's more and require 2X's more space inside.
You're in MI, perhaps you'd be better off with more east(ish) facing solar assuming you have more colder mornings than I do here in southern MO. The quicker you start producing more power the sooner your batteries start charging after the often long dark nights.
Not saying I'm right about any of that, just offering that I think that the design practices of 25 years ago when PV was $4/watt just for panels doesn't apply to today and it would interesting to dig deeper into that.
All of it facing due south gets you the most "potential" daily kWh but it may not get you the most "usable" daily kWh is what we came up with.
I think one needs to try to dig deep into thier system design to better answer this. For example, some solar farms are built facing to the west knowing that when the grid really needs thier energy is from 1PM until things start to cool off at sunset.
Our thinking was that having arrays of different orientations would allow you have a smaller battery bank. PV is cheaper than batteries plus it doesn't take up room inside your house or shop. 2X more batteries cost 2X's more and require 2X's more space inside.
You're in MI, perhaps you'd be better off with more east(ish) facing solar assuming you have more colder mornings than I do here in southern MO. The quicker you start producing more power the sooner your batteries start charging after the often long dark nights.
Not saying I'm right about any of that, just offering that I think that the design practices of 25 years ago when PV was $4/watt just for panels doesn't apply to today and it would interesting to dig deeper into that.
Last edited:
patrickparrott
New Member
What is your location in Michigan? I am installing my second array and designing my 3rd in the west Flint area.
I am just north of Ionia
patrickparrott
New Member
Directly west of my location. My first system is all Victron, roof mounted, .4kwh 250w inverter/12vdc. Working flawlessly for 3 years. The second system is a Victron/Midnite Solar system, 1.5kwh, ground mounted 3000w inverter and 24v battery. I am designing a 5kwh ground mounted all Midnite Solar with 48v batteries for the river cottage. All systems are off grid. I would like to know how you determined your east/west placement to the sun. Mine were all determined by south facing buildings with
a 45-degree panel angle.There was no science involved in it for me, I built 1 of the 3 ground mounts (adjustable angle) about 15-20 degrees towards the east from south and 1 the same towards west from the south just to pick up a bit more power earlier in the day and later in the day. The 30 panels that are roof mounted and the 10 panels of the one ground mount are all facing straight south.
Here is a quick over view I did last week of the system I built.
Here is a quick over view I did last week of the system I built.
9 am and the array that is pointed ~15 degrees towards the east off of straight south is getting double the output of the other arrays.
patrickparrott
New Member
I think that I might end up with the same thing. I'll see what the sun software shows first.
Yeah I like it, the one facing ~15 degrees towards the west was also almost double the output later in the day/evening. I plan to add two more arrays, I think I am going to angle them like those two. I already have 16k facing straight south so I think I am good there.
patrickparrott
New Member
Sounds great! I will finish my install in the spring when I return from Florida. Selecting the panels and the racking now for the 5k for the very efficient 900sqft cottage that's on the same property. I use 9kwh/day in summer and 3kwh/day in the winter. I like your ground mounts but don't have the time to build them. USA and Midnite as much as possible. 
patrickparrott
New Member
Interesting! Following this usage.....The battery was down to 7% this morning before the sun started picking up some of the load. Before noon now and batteries over 50%
View attachment 254598
registered-bum
Solar Enthusiast
You guys ever play with the feds provided free simulator - pvwatts?
It allows you to play unlimited version of what if; what if I align the east-west layout of the array at 190 and panel tilt at 40 ... then provides projections of avg # of hours per day for each month of the year. Then what if I tilt at 45 or 50, what if I align more to east at say 170 or 160?
These have been proven to be pretty good estimates - based on my small samples and arrangements for NorCal ( ~41 N and aligned 190 east-west).
Gets you smarter without too much cost of bad experiments (well shit, that didn't work - LOL.)
Also - the count of arrays and panels feeds into the approach of over-paneling.
So for example, if my SCC can only handle a max of 5Kw, and I have an array of 3Kw panels with east bias for morning, and another array of 3Kw panels for west bias for afternoon sun, then I could hope to avoid too much clipping around the noon sun and move more capture into morning and afternoon - smoothing the curve if you will. By playing with the simulator and running estimates for morning layout vs afternoon layout, I would hope to get more gross capture per day -especially during Dec-Jan-Feb when my hours are shortest. No free lunch, but maximum utilization of the SCC and available hours.
For a small array of 2.4Kw (I have 8 of the LG 310w mono panels) - wanted to see what the trade-offs were for winter vs summer months.
It allows you to play unlimited version of what if; what if I align the east-west layout of the array at 190 and panel tilt at 40 ... then provides projections of avg # of hours per day for each month of the year. Then what if I tilt at 45 or 50, what if I align more to east at say 170 or 160?
These have been proven to be pretty good estimates - based on my small samples and arrangements for NorCal ( ~41 N and aligned 190 east-west).
Gets you smarter without too much cost of bad experiments (well shit, that didn't work - LOL.)
Also - the count of arrays and panels feeds into the approach of over-paneling.
So for example, if my SCC can only handle a max of 5Kw, and I have an array of 3Kw panels with east bias for morning, and another array of 3Kw panels for west bias for afternoon sun, then I could hope to avoid too much clipping around the noon sun and move more capture into morning and afternoon - smoothing the curve if you will. By playing with the simulator and running estimates for morning layout vs afternoon layout, I would hope to get more gross capture per day -especially during Dec-Jan-Feb when my hours are shortest. No free lunch, but maximum utilization of the SCC and available hours.
For a small array of 2.4Kw (I have 8 of the LG 310w mono panels) - wanted to see what the trade-offs were for winter vs summer months.
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