Question Solar panel selection

[Kevin D Pem]

One cell shaded brings the whole system down. But wait, that's not all. Reverse voltage on the shaded panel cell takes the brunt of all the current the panel produces. That one cell over time will discolor and lower the power it produces. The whole panel is then compromised.

Series parallel is a great idea, sometimes. This is what you need to consider:

Is the power more than 2 times the battery voltage? It matters little that the controller can handle the voltage. Design data shows buck converters are most efficient when the voltage difference between the high voltage and low voltage is not over 2.5 times different. And yes an mppt controllers base is a buck converter. It there becomes obvious that wire size and parallel lead wires are more important than any other condition when considering losses coming down from the roof, as the controller will eat the gain in power in losses inherent in the buck converter.

The other option is to increase the system voltage (battery bank voltage) so higher voltages can be used coming down from the roof. On my system (24v) I do series parallel. voc is 70v and Mpp is 56v I am just at the cusp when it comes to efficiency, I may loose a little at the Buck converter but not much. Further my parallel panels are connected at the controller, Well not really. My two parallel systems come together at the same point is more like it. I have a controller for each string (500w) per controller. This was done for redundancy and possible shading in the wee hours of the day and evening. My system will produce the power available from at least one 500w string, at any one time.

My 24v inverter powers the house battery (12v)system through the converter. This battery is yes one battery only.

 

[Neal]

Here is my set up



View attachment 4655

Please share the parts that went into the motorized setup for future reference.

 

[RKins]

Remember that a clean solar panel is a happy panel. A dirty/dusty panel is not efficient. The last company I worked for before retiring, used a lot of solar panels to run our remote systems. If we had any complaints, it was solved by getting their maintenance team to add washing off the panels into the weekly PM AND replacing batteries on a 4 year schedule.

 

[Soniccruzer]

Please share the parts that went into the motorized setup for future reference.

I used a product from Solar Vector for the tilt units, @solarvector.net. Great product and Kevin the owner is great to work with. Also all my panels, controller etc came from AM Solar.
Scott

Please share the parts that went into the motorized setup for future reference.

 

[Soniccruzer]

My wife Cindy and I have been RVing for over 25 years owning three different motorhomes with solar panels on the roof. The first two had 400W of ridged tilting panels that required me to climb and manually tilt the panels to gain optimum output while boon docking. Both of these motorhomes had ladders installed and I always reluctantly climbed up to the roof to do the dirty deed of tilting.

Fast forward to our current coach a Newmar Mountain Aire which presented a whole new set of obstacles. It’s an all electric power hungry beast and has no ladder. We installed 1020W of solar to keep up but the layout which was a less than perfect and didn’t allow for much tilting without any shading of adjacent panels.

For years I thought “when is someone going to design a remote tilting system for RV’s”. I first came across Solar Vector approximately four years ago and was immediately interested. The first thing I went to work on was rearranging our current panel layout and to deal with the the roof skirting around the roof edge. The skirting is a combination of awnings and fake facades which is 10” above the roofline. I was able come up with a raised rack system which allowed me prevent any shading and place all six panels inline. With the Solar Vector overview tilt units our solar output has increased dramatically averaging 35-45% increase in solar input.

Kevin the owner is constantly working on improving the Solar Vector system and I believe he has a winner with Solar Vector 2. It’s lighter, simpler and has been huge improvement to our motorhome. Also they are about to release a new version Solar Vector 3 which will track the sun and be able to handle larger and heavier residential panels. Their product and customer service is second to none and would be a great addition to any solar powered RV.


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[Hoshi]

I have been reading the list of solar info that was provided here. One question I do have is the addition cost of Obsidian roof mounted Panels worth the cost?

 

[Kevin D Pem]

I have been reading the list of solar info that was provided here. One question I do have is the addition cost of Obsidian roof mounted Panels worth the cost?

The best way to answer that is with a statement I received the first time I got some solar.

"there are only two kinds of solar panel. Those that are mounted and those that are broken"

In my years full timing my observation is he was correct.

 

[Hoshi]

The best way to answer that is with a statement I received the first time I got some solar.

"there are only two kinds of solar panel. Those that are mounted and those that are broken"

In my years full timing my observation is he was correct.

well, they are mounted I am just not sure about the different qualities of panels? Humor an old woman.

 

[Kevin D Pem]

"A" panels are grid grade panels. "B" grade panels are off grid panels because of quality. Efficiency increases may be available and is used by manufacturers to sell panels. Lets look at efficiency:

One square meter of surface gets 1000 watts of sun energy. The amount of energy converted by the panel is a percent of that power. It is that percent of power that is stated when we look at panels. That said the area you give up on a roof is based on that value. This of course does not include the area lost to frame structure. If the panel is a grade "A" panel it has a 20 year guaranty to produce no less than 80% of the original value.

For most of us We will have space left on the roof after we have all the panel we want. What this says is we really should not be concerned about efficiency because we still have space on our roofs.

Because On grid solar panels must meet a set standard to be used on grid("A") any panel that meets that standard is for the most part equivalent. You may see a difference in cell alignment but that is where it ends.

for mobile use frame build is important but only on a very poorly built coach. For heat transfer the panels should have a space of no less than 2" under them. More is better.

The best money spent is on an MPPT controller as the losses for the other cheap PWM controllers are large.

Battery type is also important. AGM have less resistance than flooded making them charge faster(less loss of power from the panel). I will make the point that in the north where freezing weather is the norm much of the year, Lithium is a bad idea on a working solar system in a house that is not kept above 32 deg Fahrenheit at all times during the daylight hours.

I upgrade all wire for solar. If awg 10 wire is good enough I use awg 6. any loss or heat of any amount that is measurable is loss of energy.

I hope this helps. If it is more than you asked for, I am sorry. If you understand what you are trying to achieve it is easier to make choices that fit.

 

[Hoshi]

"A" panels are grid grade panels. "B" grade panels are off grid panels because of quality. Efficiency increases may be available and is used by manufacturers to sell panels. Lets look at efficiency:

One square meter of surface gets 1000 watts of sun energy. The amount of energy converted by the panel is a percent of that power. It is that percent of power that is stated when we look at panels. That said the area you give up on a roof is based on that value. This of course does not include the area lost to frame structure. If the panel is a grade "A" panel it has a 20 year guaranty to produce no less than 80% of the original value.

For most of us We will have space left on the roof after we have all the panel we want. What this says is we really should not be concerned about efficiency because we still have space on our roofs.

Because On grid solar panels must meet a set standard to be used on grid("A") any panel that meets that standard is for the most part equivalent. You may see a difference in cell alignment but that is where it ends.

for mobile use frame build is important but only on a very poorly built coach. For heat transfer the panels should have a space of no less than 2" under them. More is better.

The best money spent is on an MPPT controller as the losses for the other cheap PWM controllers are large.

Battery type is also important. AGM have less resistance than flooded making them charge faster(less loss of power from the panel). I will make the point that in the north where freezing weather is the norm much of the year, Lithium is a bad idea on a working solar system in a house that is not kept above 32 deg Fahrenheit at all times during the daylight hours.

I upgrade all wire for solar. If awg 10 wire is good enough I use awg 6. any loss or heat of any amount that is measurable is loss of energy.

I hope this helps. If it is more than you asked for, I am sorry. If you understand what you are trying to achieve it is easier to make choices that fit.

THAK YOU, THIS ACTUALLY HELPS A LOT.