Solar Tracker

Northern_BC · September 2016

Hello. I am adding additional solar to my system to help with winter production. Can anyone provide some feedback on how efficient fixed solar panels are when the sun is not directly shining perpendicular to them; early morning and late afternoon. I have a tracker and like it, but the cost to mount them is so much more than a fixed system.

Am I better off adding more fixed panels and getting indirect light to them each side of 12pm, than a tracker setup, where I live gets direct sunlight 6am to 8pm in the summer? In the winter the tracker makes little difference as I only get sun from 10 am to 4pm and mostly directly south only. Power usage is 2.5 times more in the winter than summer.

Thanks.

westbranch · September 2016

You a re just about 1 hr more than we get in winter...solution IMHO is to over -panel in a fixed direction in winter see https://forums.energymatters.com.au/solar-wind-gear/topic5064.html

I'm at ~ 54 * N lat 124W and I have my panels sort of optimized for winter, steep angle to shed snow as lots o input in summer. Only 3 arrays (4 in series) placed so far with 5 more to go...

Dave Angelini · September 2016

I like both and often do the second + array fixed. I assume you are offgrid. You get off the battery earlier in the morning and go on it later in the day being tracked. The larger power use devices can be shifted to the middle part of the day. We heat electrically with a heat pump and run electric ovens on the decent winter days and shift to propane for cooking and a wood stove in the bad days of winter.

You gain about 30% with a single axis tracker but that number is really a grid-tie number where you are selling it all.
For offgrid, it is the hours of battery use saved that really is the magic wandu!

Photowhit · September 2016

Northern_BC said:

Hello. I am adding additional solar to my system to help with winter production. ....

Am I better off adding more fixed panels and getting indirect light to them each side of 12pm, than a tracker setup, where I live gets direct sunlight 6am to 8pm in the summer? In the winter the tracker makes little difference as I only get sun from 10 am to 4pm and mostly directly south only. Power usage is 2.5 times more in the winter than summer.

You will get close to full production a couple hours either side of solar noon and 70+ % the other hours during winters 10-4 hours of sunlight. For Winter production, I would not use a tracker. I would angle the panels close to the winter angle of the sun, If you are in BC perhaps 10 degrees less, unless you have a lot of snow days.

westbranch · September 2016

Another benefit of almost vertical orientation is that on clear days you get an increase in panel output from reflection off the snow, that an MPPT CC can harvest,

Dave Angelini · September 2016

Photowhit said:

Northern_BC said:

Hello. I am adding additional solar to my system to help with winter production. ....

Am I better off adding more fixed panels and getting indirect light to them each side of 12pm, than a tracker setup, where I live gets direct sunlight 6am to 8pm in the summer? In the winter the tracker makes little difference as I only get sun from 10 am to 4pm and mostly directly south only. Power usage is 2.5 times more in the winter than summer.

You will get close to full production a couple hours either side of solar noon and 70+ % the other hours during winters 10-4 hours of sunlight. For Winter production, I would not use a tracker. I would angle the panels close to the winter angle of the sun, If you are in BC perhaps 10 degrees less, unless you have a lot of snow days.

He has a tracker and probably can angle the array verticle. Why would you reccomend not tracking, seems crazy when he has one and will get longer hours of power, maybe not much more at that latitude in winter but certainly not less!

Northern_BC · September 2016

What about the benefits to the batteries that a tracker could give? Wouldn't the batteries be happier (longer lifespan) staying on a float charge longer throughout the day? Where the power coming in from solar is greater than the power going out to the house. The tracker would provide a charge a few hours more in the morning and evening than a fixed array.

After 10 years off grid now, my batteries are treated like children and I want what is best for them. Spent a lot of money on batteries to get the good system I have now.

Photowhit · September 2016

Dave Angelini said:

Photowhit said:

Northern_BC said:

I have a tracker and like it, but the cost to mount them is so much more than a fixed system.

He has a tracker and probably can angle the array verticle. Why would you reccomend not tracking, seems crazy when he has one and will get longer hours of power, maybe not much more at that latitude in winter but certainly not less!

I dropped in his quote from the original post.

It sounded to me like he was weighing the cost between having an addition, as in purchasing another, tracker...
...or using a fixed array, with the primary use being additional winter charging; "...Power usage is 2.5 times more in the winter than summer."

If he was needing more power during the summer, I might agree, though given space and the costs, I might do a southeast and/or southwest arrays, depending on micro climate.

The sun moving 15 degrees an hour, and having 6 hours of available sun, the tracker for winter hours doesn't seem to be too cost effective.

Dave Angelini · September 2016

One of the best reasons to track offgrid is the health of your batteries.

Image: https://us.v-cdn.net/6024911/uploads/editor/2d/nc9zc5moubqt.png

Photowhit · September 2016

Northern_BC said:

What about the benefits to the batteries that a tracker could give? Wouldn't the batteries be happier (longer lifespan) staying on a float charge longer throughout the day? Where the power coming in from solar is greater than the power going out to the house. The tracker would provide a charge a few hours more in the morning and evening than a fixed array.

After 10 years off grid now, my batteries are treated like children and I want what is best for them. Spent a lot of money on batteries to get the good system I have now.

Your current tracking system will help maintain the float level in the morning and into the evening.

Dave Angelini · September 2016

"The sun moving 15 degrees an hour, and having 6 hours of available sun, the tracker for winter hours doesn't seem to be too cost effective."

Agree the decision may not be cost effective but to some people in some places cost is not the only objective.
A different objective might be not having to run a generator. Pretty decent harvest when the sun pokes out for an hour at the extremes of the day.
Where I live in the mountains, we often get a full hour of sun at the end of a bad winter the day.
There are always different objectives

vtmaps · September 2016

Northern_BC said:

Can anyone provide some feedback on how efficient fixed solar panels are when the sun is not directly shining perpendicular to them; early morning and late afternoon. I have a tracker and like it, but the cost to mount them is so much more than a fixed system.

You can have both a tracker and a fixed system. It's called virtual tracking. Instead of having all your panels fixed in one position, divide the array in two and fix some of them to the southeast and some to the southwest. You can do that on a single controller.

Panels are historically cheap... if you want to increase your solar harvest by 25%, it's probably more cost effective to add 25% more panels than to try to gain that 25% with a mechanical tracker.

--vtMaps

Northern_BC · September 2016

My plan was to use a virtual tracking system. I wanted to build a stand that allowed me to rotate the array. In the winter they would face straight south, and in the summer I would turn an array southeast and another array southwest. The problem is I can't come up with a good way to do this. I don't have the tools (and skills) to fabricate a stand that allows me to turn it horizontally. I can only really work with wood for stand portion. I can buy a stand like what my tracker array its on, but it is expensive, and for the cost I can pay a bit more and have it track. The stand is the expensive part to get built. Maybe someone here has some good ideas.

westbranch · September 2016

Northern_BC, where are you , roughly? There are a few homebrew moveable arrays around my area...

Northern_BC · September 2016

I live near Fort St John.

westbranch · September 2016

I'm west of Williams Lake, so I don't think it would be worth the drive... too bad \i will see if I can find some old photos..

t00ls · September 2016

I dont understand why it would cost more to mount panels on a tracker...what am I missing

Photowhit · September 2016

They have to pivot at a single point, or hinge at one point, so the structure/racking is much more expensive, also the tracker it's self isn't free...

Dave Angelini · September 2016

t00ls said:

I dont understand why it would cost more to mount panels on a tracker...what am I missing

I do not think you are missing anything. In some offgrid applications it is the best way to get long hours of solar power.
The other way is a huge battery and a very large south array, or north on the other side of the world.

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