Sliding Solar Panel Rack Systems by Orion Designs

OrioN

2008 2500 170" EXT
Are you saying one would need separate controllers for bifacial panels to handle the voltage difference from retracted panels? I thought wiring panels in parallel to a single controller could handle the voltage difference from a shaded panel. If parallel wiring won't handle the voltage difference I can understand why normal lower panels must be shut off when retracted. Including a shut-off switch for the lower panels will complicate the installation a bit.

I was thinking of a four panel system with each layer of two panels in series and then the series pairs paralleled to the controller. Think I might need to get smarter on solar installations.
I believe I have misspoke or erred previously.

One MPPT controller can effectively and efficiently work for bifacial arrays and when they are retracted. The upper and lower arrays would need to be wired in series, where their different voltages add to and compliment each other.

I'd also wire the array's panels in series, as I'm an advocate of higher voltage.

https://www.electronics-tutorials.ws/dccircuits/voltage-source.html

One third down the page:

Connecting Voltage Sources Together
Ideal voltage sources can be connected together in both parallel or series the same as for any circuit element. Series voltages add together while parallel voltages have the same value. Note that unequal ideal voltage sources cannot be connected directly together in parallel.

Voltage Source in Parallel
While not best practice for circuit analysis, ideal voltage sources can be connected in parallel provided they are of the same voltage value. Here in this example, two 10 volt voltage source are combined to produce 10 volts between terminals A and B. Ideally, there would be just one single voltage source of 10 volts given between terminals A and B.

What is not allowed or is not best practice, is connecting together ideal voltage sources that have different voltage values as shown, or are short-circuited by an external closed loop or branch.

Badly Connected Voltage Sources
However, when dealing with circuit analysis, voltage sources of different values can be used providing there are other circuit elements in between them to comply with Kirchoff’s Voltage Law, KVL.

Unlike parallel connected voltage sources, ideal voltage sources of different values can be connected together in series to form a single voltage source whose output will be the algebraic addition or subtraction of the voltages used. Their connection can be as: series-aiding or series-opposing voltages as shown.

Voltage Source in Series
Series aiding voltage sources are series connected sources with their polarities connected so that the plus terminal of one is connected to the negative terminal of the next allowing current to flow in the same direction. In the example above, the two voltages of 10V and 5V of the first circuit can be added, for a VS of 10 + 5 = 15V. So the voltage across terminals A and B is 15 volts.

Series opposing voltage sources are series connected sources which have their polarities connected so that the plus terminal or the negative terminals are connected together as shown in the second circuit above. The net result is that the voltages are subtracted from each other. Then the two voltages of 10V and 5V of the second circuit are subtracted with the smaller voltage subtracted from the larger voltage. Resulting in a VS of 10 – 5 = 5V.

The polarity across terminals A and B is determined by the larger polarity of the voltage sources, in this example terminal A is positive and terminal B is negative resulting in +5 volts. If the series-opposing voltages are equal, the net voltage across A and B will be zero as one voltage balances out the other. Also any currents (I) will also be zero, as without any voltage source, current can not flow.



Anyone see issue here? Do the watts also stack up and the net result is more input amperage? :thinking:





.
 
Last edited:

HarryN

Active member
I am perceiving it as two situations:
- panels retracted
- panels extended

In both situations, I would want solar charging to work without making any electrical connection changes and without thought.

For this reason, I would be tempted to have the panel array that is always exposed in parallel with the panel array that retracts.

If that can be done with 1 or 2 controllers in parallel isn't that big of deal IMHO.
 

OrioN

2008 2500 170" EXT
I am perceiving it as two situations:
- panels retracted
- panels extended

In both situations, I would want solar charging to work without making any electrical connection changes and without thought.

For this reason, I would be tempted to have the panels that are always exposed in parallel with the panels that retract.

If that can be done with 1 or 2 controllers in parallel isn't that big of deal IMHO.
Thinking from my pocket book perspective, I can get a few multi-pole changeover switches say $100, or a second Tristarr MPPT 45 or 60 for $400-500...... :hmmm:
 

Midwestdrifter

Engineer In Residence
Depending on how the panels are wired, a blocking diode on the covered string should prevent it from pulling the non-shaded parallel string down.
 

Boxster1971

2012 Sprinter 3500 Ext
Two controllers is a small price to pay for extended vs non extended operation.

I just did a project with 3 controllers to optimize a customer's special requests / ideas.

Nice to see the project moving along.
After doing some additional reading I would agree with you that two controllers would be the best approach. Apparently anytime you have panels that get differing exposures it is best to have them on independent controllers.
 

Boxster1971

2012 Sprinter 3500 Ext
I believe I have misspoke or erred previously.

One MPPT controller can effectively and efficiently work for bifacial arrays and when they are retracted. The upper and lower arrays would need to be wired in series, where their different voltages add to and compliment each other.

I'd also wire the array's panels in series, as I'm an advocate of higher voltage.

https://www.electronics-tutorials.ws/dccircuits/voltage-source.html . . .

. . . Anyone see issue here? Do the watts also stack up and the net result is more input amperage? :thinking: .
I'm thinking separate controllers for the upper and lower panels, as you previously recommended, would be best to get maximum output.

There are four 100W panels on my van now - all wired in parallel. Planning to change them to two series pairs connected in parallel, raising the voltage to my BlueSky MPPT controller for better low sun performance. The controller has a 50V max so I can't connect them all in series. Before making changes I will do some tests to simulate stacked panels by shading some panels and see what results.
 

HarryN

Active member
After doing some additional reading I would agree with you that two controllers would be the best approach. Apparently anytime you have panels that get differing exposures it is best to have them on independent controllers.
You might be forced to add a second controller anyway. I think that you have the BS 3000 / 12 volt / 30 amp output? (30 amps) x (12 volts) is going to be on the lite side for 800 watts of panels.
 

autostaretx

Erratic Member
Solar systems for residential roof installations lean heavily on "microinverters" ... each panel has its own inverter.
There are quad microinverters (4 panels' input, one 208vac output) for $330: https://www.ecodirect.com/APsystems-QS1-MC4-Micro-Inverter-p/apsystems-qs1.htm
Since microinverters (one per panel) are around $100.
Yes: i realize that's a "grid-tie" unit (want to see 50/60 Hz AC on its "output" before it sends out power), but it's an example of available technology for handling randomly-shaded installations.

Their AC output makes them "ready" for a Graphite Dave (i.e. AC distribution within the van) flavor of system.

The required "grid" can be faked.
--dick
 

rollerbearing

Well-known member
Autostaretx - just to be clear for those who maybe don't know such things - I assume you are not advocating driving an Orton Inverter.

The Micro inverters require a "stiff" near infinite sink. One of the tests they do to see if the mains are present is by blipping them to see if they can perturb the voltage (they can't budge the main's voltage). Also the mains must be able to sink the current injected into them - effectively driving an Orton inverter in reverse (maybe smoke).

At least this was my understanding of the Enphase microinverters of a few years ago. It's possible that things have changed.
 
Last edited:

Boxster1971

2012 Sprinter 3500 Ext
You might be forced to add a second controller anyway. I think that you have the BS 3000 / 12 volt / 30 amp output? (30 amps) x (12 volts) is going to be on the lite side for 800 watts of panels.
I wasn't clear. My current van has four 100W panels and a Blue Sky SB2512iX-HV MPPT controller. This system was installed in 2014 and has worked great for five years now.

But I'm planning for a new B-van on a 144" Sprinter next year. This stacked solar rack system might allow me to squeeze 800W with four of these 200W HIGHTEC bifacial solar panels.

https://www.ebay.com/itm/200-25-Wat...at-highest-power-12V-you-can-buy/264459855170

I haven't got all the details worked out yet, but I don't want propane again. I'd like all electric on the coach side with vehicle fuel for off-grid heating. I'll use a controller or multiples as needed.
 

OrioN

2008 2500 170" EXT
I wasn't clear. My current van has four 100W panels and a Blue Sky SB2512iX-HV MPPT controller. This system was installed in 2014 and has worked great for five years now.

But I'm planning for a new B-van on a 144" Sprinter next year. This stacked solar rack system might allow me to squeeze 800W with four of these 200W HIGHTEC bifacial solar panels.

https://www.ebay.com/itm/200-25-Wat...at-highest-power-12V-you-can-buy/264459855170

I haven't got all the details worked out yet, but I don't want propane again. I'd like all electric on the coach side with vehicle fuel for off-grid heating. I'll use a controller or multiples as needed.

How does 1.2kW sound to you? I just sent the shop drawing to fabricator for the SR3x Stacking Coupler which allows for stacking a SR2x on a SR1x, thereby an array can extend from both sides....


SRxx-122019-2.jpg
 

Boxster1971

2012 Sprinter 3500 Ext
How does 1.2kW sound to you? I just sent the shop drawing to fabricator for the SR3x Stacking Coupler which allows for stacking a SR2x on a SR1x, thereby an array can extend from both sides....
Excellent - don't know if I need 1,200W, but that would also allow me to get 600W with a triple stack if I run out of roof space on a 144. Need a MaxxAir roof vent fan and an A/C unit. Considering A/C other than a roof unit, but there are so many trade-offs.

Happy New Year!!
 

Boxster1971

2012 Sprinter 3500 Ext
Orion - I'm wondering if your prototypes have a similar one-side only linear actuator?

Looking at the diagrams the actuator mounted on the side might cause the slide-out panel to bind?

Also - can one add the automatic extension actuator later after installing the manual version?
 

OrioN

2008 2500 170" EXT
Orion - I'm wondering if your prototypes have a similar one-side only linear actuator?

Looking at the diagrams the actuator mounted on the side might cause the slide-out panel to bind?

Also - can one add the automatic extension actuator later after installing the manual version?
The Motor Kits (actuator) are mounted on one side only. When the rack system is installed correctly as per the Installation Manual, the bearing will not bind with or without the actuator and when a force is applied to one corner in the direction of the bearing or extension/retraction motion.

The Motor Kit is available as an option, and with left or right side option.
 

Boxster1971

2012 Sprinter 3500 Ext
Are your plans for this project being impacted by the COVID-19 pandemic? I'm now delaying my new van purchase into next year - too much uncertainty to move ahead now.
 

Top Bottom