DEEP CYCLE BATTERIES and BUSH POWER
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condor22
Mike
Thought I would add a little info re solar panels and try to keep it simple, however, there is some math involved. I'll also make a note of Watts Law re power.
A = amps, V = Volts, W = Watts
The equation used is V x A = W and I'll ignore any variables or efficiency crap to keep it simple. The scenario explains 2 different panels and there output in parallel and series connection. I will round the figures to keep it simple, but the effect is similar whatever the figure. There is a Rule re both types of connection.
In Parallel connection the A outputs of each panel are added and the lower of the panel V is used.
In Series connection the V outputs of each panel are added and the lower of the panel A is used.
Having said this, I will use the following; 1 x 100W panel, rated at 5A @ 18V and 1 x 200W ppanel, rated at 10A @ 22V. (note, larger panels are often rated with higher V than smaller. These figures are before entering the controller and are nominally for a 12V system, but, the same logic applies to 24V & 48V systems.
Next post.........
A = amps, V = Volts, W = Watts
The equation used is V x A = W and I'll ignore any variables or efficiency crap to keep it simple. The scenario explains 2 different panels and there output in parallel and series connection. I will round the figures to keep it simple, but the effect is similar whatever the figure. There is a Rule re both types of connection.
In Parallel connection the A outputs of each panel are added and the lower of the panel V is used.
In Series connection the V outputs of each panel are added and the lower of the panel A is used.
Having said this, I will use the following; 1 x 100W panel, rated at 5A @ 18V and 1 x 200W ppanel, rated at 10A @ 22V. (note, larger panels are often rated with higher V than smaller. These figures are before entering the controller and are nominally for a 12V system, but, the same logic applies to 24V & 48V systems.
Next post.........
condor22
Mike
Example 1 in Parallel remembering "In Parallel connection the A outputs of each panel are added and the lower of the panel V is used."
Amps added = 10+5=15 and the lower V=18, therefore 15x18=270W which is 90% efficiency.
Example 2 in Series remembering "In Series connection the V outputs of each panel are added and the lower of the panel A is used."
Volts added = 18+22=40 and the lower A=5, therefore 40x5=200W which is 66% efficiency. In this example, if your original panel is the 200W and you add the 100W, you gain zero W.
Having shown these examples, there are two points to make;
1. The only way of achieving as close to 100% efficiency from a bank of solar panels is to use the same type, size, make etc panels with the rated specs identical. Regardless of connecting in series or parallel.
2. Why use series? Answer next post.......
Amps added = 10+5=15 and the lower V=18, therefore 15x18=270W which is 90% efficiency.
Example 2 in Series remembering "In Series connection the V outputs of each panel are added and the lower of the panel A is used."
Volts added = 18+22=40 and the lower A=5, therefore 40x5=200W which is 66% efficiency. In this example, if your original panel is the 200W and you add the 100W, you gain zero W.
Having shown these examples, there are two points to make;
1. The only way of achieving as close to 100% efficiency from a bank of solar panels is to use the same type, size, make etc panels with the rated specs identical. Regardless of connecting in series or parallel.
2. Why use series? Answer next post.......
condor22
Mike
Series- Let's use the 100W panel as the example in both Parallel and series;
Example 1 in Parallel remembering - Amps added = 5+5=10 and the V=18, therefore 10x18=180W which is 90% efficiency. (also remember I rounded the figures a 100V panel is 18+V and 5+A and in reality will =100%
Example 2 in Series remembering - Volts added = 18+18=36 and the lower A=5, therefore 36x5=180W which is the same output as Parallel.
Answer to Q. = I will use a Lithium Deep Cycle as the example, mine still shows 13.1V at 60% State of Charge (SOC). A Victron Blue Smart solar controller, start charging when the solar panel output reaches 5V more than battery volts. (BV) and stops when that difference goes below 1V. This means panel V needs to be 18.1V before it starts charging (forgetting the rounding) which is very close to the maximum panel output.
Effectively in the earlier and later part of the day, especially in winter, this voltage may only be reached a couple of hours before and after mid day.
However, if panel V = 10V only earlier or later in that same day, by adding the panel voltage to = 20V, charging will start earlier, albeit at a lower A. But better than nothing if it hasn't started to charge.
Which is why the Victron, I'm looking at for my new van is the 100/30 model. those figures mean it will accept up to 10VDC and output up to 30A.
The reason parallel or Series has not been as big an issue in the past is that an AGM at 50% SOC or less, especially under load, will be very close to 12V. Adding 5V to this is still under the panel voltage at 17V.
Hope this helps, not to long and convoluted. More.....
Example 1 in Parallel remembering - Amps added = 5+5=10 and the V=18, therefore 10x18=180W which is 90% efficiency. (also remember I rounded the figures a 100V panel is 18+V and 5+A and in reality will =100%
Example 2 in Series remembering - Volts added = 18+18=36 and the lower A=5, therefore 36x5=180W which is the same output as Parallel.
Answer to Q. = I will use a Lithium Deep Cycle as the example, mine still shows 13.1V at 60% State of Charge (SOC). A Victron Blue Smart solar controller, start charging when the solar panel output reaches 5V more than battery volts. (BV) and stops when that difference goes below 1V. This means panel V needs to be 18.1V before it starts charging (forgetting the rounding) which is very close to the maximum panel output.
Effectively in the earlier and later part of the day, especially in winter, this voltage may only be reached a couple of hours before and after mid day.
However, if panel V = 10V only earlier or later in that same day, by adding the panel voltage to = 20V, charging will start earlier, albeit at a lower A. But better than nothing if it hasn't started to charge.
Which is why the Victron, I'm looking at for my new van is the 100/30 model. those figures mean it will accept up to 10VDC and output up to 30A.
The reason parallel or Series has not been as big an issue in the past is that an AGM at 50% SOC or less, especially under load, will be very close to 12V. Adding 5V to this is still under the panel voltage at 17V.
Hope this helps, not to long and convoluted. More.....
condor22
Mike
Conclusions, Benefits and Problems.
1. Balance multiple panels, size, specs, output V, A & W as close as possible to gain greatest efficiency.
Parallel connection -
Benefits - Less loss of efficiency with mismatch. Easier to wire when adding panels. If one panel goes down another will still produce power. (Assuming panels are able to be isolated).
Problems - On days of iffy sun, reduced voltage reduces output. Heavier wiring needed as Amps are added. More prone to Voltage drop.
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Series Connection - Virtually the opposite of Parallel -
Benefits - On days of iffy sun, increased voltage increases output. Lighter wiring needed as less Amps. Less prone to Voltage drop.
Problems - More loss of efficiency with mismatch. Wiring, particularly when adding portable panels needs consideration. If one panel goes down all go down.
1. Balance multiple panels, size, specs, output V, A & W as close as possible to gain greatest efficiency.
Parallel connection -
Benefits - Less loss of efficiency with mismatch. Easier to wire when adding panels. If one panel goes down another will still produce power. (Assuming panels are able to be isolated).
Problems - On days of iffy sun, reduced voltage reduces output. Heavier wiring needed as Amps are added. More prone to Voltage drop.
---------------------------------------------------------------------------------------------------------------------------------------------------------
Series Connection - Virtually the opposite of Parallel -
Benefits - On days of iffy sun, increased voltage increases output. Lighter wiring needed as less Amps. Less prone to Voltage drop.
Problems - More loss of efficiency with mismatch. Wiring, particularly when adding portable panels needs consideration. If one panel goes down all go down.
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With my Lithium it has a voltage range of 16 to 60v+ so when I hook panels in series the Higher the Voltage, The higher the Voltage means more watts,
This all works out fine if I keep the Amps under 10A, If I put 2 in series I can get around 250 to 300w, If I put 3 in series I can get IE 375 to around 480w with the votage around 54 to 60v,
If One panel gets shaded then I am getting a reduced Voltage which means my Watts are Lower but I am still getting over 18V+, where I can get 18v from One panel and IE 11v from another panel fo my Voltage gets reduced to around 29v instead of 36 to 40v+/-, OR 18v + 18v + 11v = 47v but I still get the Watts those voltages produced,
If I over Volt and put 4 panels in series the PowerOak/Bluetti EB180 puts up and error code and won't charge until I remove the 4th Panel and reset the EB180, The Internal Input is 600w but it is Capped at 500w and the most wattage it will allow in is 505w / 64v +/-, I can over Watt the sysem to make sure I get full power on cloudy days BUT I can't Over Volt the System or it puts up the Error Code and shuts down.
This all works out fine if I keep the Amps under 10A, If I put 2 in series I can get around 250 to 300w, If I put 3 in series I can get IE 375 to around 480w with the votage around 54 to 60v,
If One panel gets shaded then I am getting a reduced Voltage which means my Watts are Lower but I am still getting over 18V+, where I can get 18v from One panel and IE 11v from another panel fo my Voltage gets reduced to around 29v instead of 36 to 40v+/-, OR 18v + 18v + 11v = 47v but I still get the Watts those voltages produced,
If I over Volt and put 4 panels in series the PowerOak/Bluetti EB180 puts up and error code and won't charge until I remove the 4th Panel and reset the EB180, The Internal Input is 600w but it is Capped at 500w and the most wattage it will allow in is 505w / 64v +/-, I can over Watt the sysem to make sure I get full power on cloudy days BUT I can't Over Volt the System or it puts up the Error Code and shuts down.
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Gavin of Garfield
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What I do is when i set up camp for four weeks, is place my two moveable panels out connect the 100 watt panel to my camper to charge my 100 amp agm and the other 160 watt panel to my 130 amp agm which powers my two fridges. Panels are moved thru out the day and apart from the odd check on my trusty volt meter that's it. I think it's know as the KISS principle 
layful:
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Diginit said:What I do is when i set up camp for four weeks, is place my two moveable panels out connect the 100 watt panel to my camper to charge my 100 amp agm and the other 160 watt panel to my 130 amp agm which powers my two fridges. Panels are moved thru out the day and apart from the odd check on my trusty volt meter that's it. I think it's know as the KISS principle
That's pretty much how the EB180 works, you just link the panels and plug in the lead, there is nothing for the user to get involved with, which is why I went for this model, It was all about the power In and the power out, They make other models by the same company where you can use an app and tweak the settings But I just wanted a PlugNPlay setup and I can charge it from flat in just over 3 hours which is all that matters for me. :Y:
Yup, higher the voltage, less current...
Advantage being less gauge wire over long runs..
Danger in high voltage around the camp...
However, its the mills that kills, the volts just jolt...
There is no doubt, IMO, that for a camping or a short stay set up, parallel solar networks are the most advantageous.
Advantage being less gauge wire over long runs..
Danger in high voltage around the camp...
However, its the mills that kills, the volts just jolt...
There is no doubt, IMO, that for a camping or a short stay set up, parallel solar networks are the most advantageous.
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Gavin of Garfield
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100% no risk correct.Simmo said:
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Simmo said:
Yeah I think your spot on there,
To avoid the confussion about series and parallel I bought a couple of sets of "Y" Connectors so I can run one bank of panels in series and another bank in series and then put both banks in Parallel, So I end up with 2 lots of 450w in Parallel and I can keep the voltage under 60v.
I just found out that modern panels now have the normal Blocking Diode that stops the current going backwards, BUT now they have a Bypass Diode that If a panel is being shaded it Bypasses that panel so the full power of the Unshaded panels gets to the Charge Controller,
That explains how or why the panels still charge, These panel companies never tell you the important stuff like this which is why there is so much confussion about panels in series keep working if one or more are being shaded. ]
] The more I Learn the Less I Know. :argh: :argh: ]
condor22
Mike
Adding to my previous posts, there maybe occasions where one may want the option to have both parallel and series connections as an option in a caravan/camper.
If anyone is interested I can post a circuit diagram of how to do this without switches. Let me know
If anyone is interested I can post a circuit diagram of how to do this without switches. Let me know
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Simmo said:
Yeah Simmo,
Heres One but I am still trying to work out what they are saying,??
I will look for something that is in words I understand,
https://www.solaredge.com/sites/default/files/se_technical_bypass_diode_effect_in_shading.pdf
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Simmo said:
Simmo, this one explains it better,
https://www.alternative-energy-tutorials.com/photovoltaics/bypass-diode.html
That's awesome mate, thanks!
I wasn't aware that a shaded panel went reverse polarity, I thought it just stopped producing and therefore affected every panel after it in the series.
So now I can see how the diode would work!
I wasn't aware that a shaded panel went reverse polarity, I thought it just stopped producing and therefore affected every panel after it in the series.
So now I can see how the diode would work!
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Simmo said:
Yeah the Bypass Diode does all that, and also in the little Black Box on the back of the panels is a Blocking Diode as well and it's job is when it gets Dark it stops the power in the battery going back in to the Solar Panel, 1) so it can't drain the Battery and 2) so the Battery can't damage to Panel.
Two tiny things that most of us never knew about, I knew about the Blocking Diode but not the bypass diode,
I had a panel kill 2 pairs of batteries in one of my Mitsubishi's before I found out what was doing it, IE No Blocking Diode, Cheap panel and 4 expensive batteries, LOL, ]
] ]
RR, Did you try "jump starting" the dead batteries to try and get them charging again?
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Nightjar said:
Yeah they got that low they reversed their polarity and I had to reverse them again to get them back to normal,
The panel I used was a 15w panel from a Dick Smiths / Tandy's over here and it said just clip it on the battery with the attached leads Thing is even a panel with that output needs a charge controller to regulate the flow and the volts and it killed my batteries in the process, ]
] I did get the polarity back the right way but they would never hold any voltage longer than 3 or 4 days, :N:
