Added 800w solar to Hymer Exsis-I

Urs4_2008

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Hi

Just wanted to share some information of my latest install in my MH. I've had a few MH with solar, and I really enjoy leaving the power cable at home during summer season. I've tried to stretch the season as far as possible in both ends by adding 800w of flexible solar panels to the roof.

This will produce probably about 4-500 watts in normal conditions, since the panels are flat on the roof. This will allow for quite rapid charging in good conditions and some charging in various bad conditions. The setup is today as follows:

8 100w fexible panles glued to the roof on the edges using Trans7 glue, carefully avoiding shadowgenerating hatches, antennaes etc.
The configuration is 4s2p, which generates about 100 volts in the drop cable, allowing for only 4mm2 diametre without too much loss / heat.
The charger is a rather big Victron MPPT 70/150 which for now is limited at about 40 amps, until lifepo4 or similar maybe will be mounted.
Everything mounted in a way that makes it possible to remove without too much permanent damage. The drop cable is threaded through the air duct in the kitchen cupboard, avoiding to make a new hole in the roof.
The cables on the roof are zip tied to small, square zip tie connectors which are mounted to the roof using double sided tape.
Quite low impact on weight, quite easy to install, quite easy to remove and reconfigure.

Any questions, please ask :)

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scotjimland

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no questions other than why .. ?

I would have used mini- trunking for the cable runs .. as they may generate wind noise.. and vibration when driving..

forgot to ask,, what storage capacity do you have ?
 
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Urs4_2008

Urs4_2008

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no questions other than why .. ?

I would have used mini- trunking for the cable runs .. as they may generate wind noise.. and vibration when driving..
The cables are very tightly attached to the roof using zip ties - no vibrations and no noise. Tested in quite an impressive speed :censored: But trunking was (and still is) an option. I'm checking everything now after a bad winter. If some of the zip ties are loose, I will probably take your advice :)

Why? Because we're mostly travelling and sleeping on different places in nature. 99% of the journeys away from a power outlet. In Norway you are allowed to stop over and sleep everywhere you like.

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Freespirit1

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Ok @Urs4_2008 - nice installation and good you have connected them in series! The volts at 100v seems a bit low - those are semi- flexible panels I believe not flexible - what is the rated output voltage of each panel please?:)
 

Freespirit1

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Yes, semi flexible. It's about 100v, depends on a few different conditions. 4 in series parallelled with 4 in series.

View attachment 217319

Ah! That accounts for your lower voltage then - presumably because your controller is not rated at 150v ? With that series and parallel I would have thought your max power voltage would be about 72v? :)

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hilldweller

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My goodness, that's one big willie you are waving. I've never seen anything like that size in here before. But you will get a decent charge in the winter, which I guess is why you have done this.

You'll have enough sell in the summer, you could offer a charging service to ebike users.
 
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Urs4_2008

Urs4_2008

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Compensation... :) The plan was to get at least some charging during cloudy / bad weather to allow for always (not during extreme winter) leaving the power cable at home. But on sunny days I will of course offer some pixies to the ebike users, for a small fee ;)
 
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Urs4_2008

Urs4_2008

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Ah! That accounts for your lower voltage then - presumably because your controller is not rated at 150v ? With that series and parallel I would have thought your max power voltage would be about 72v? :)
The controller is rated at 150 volts. Sorry, I remembered wrong about the panels open voltage. I thought the panels were 25v nominal. But in sunny weather, and batteries fully charged, the voltage can reach 80-90 volts. Every panel in series would reach in excess of 160 volts, which is more than the 150 volts the controller accepts. That's why there are 2 strings of 4 panels in series connected in parallell before dropping down to the controller.

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Urs4_2008

Urs4_2008

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What battery capacity are you feeding into ?
Good question :) Just a dual 95 Ah regular lead acid - as cheap as they come. :) That is why I have a soft charging limit of only about 40 amps now. But the plan is to build my own lifepo4 battery which supports everything it can get. Either a complete replacement or as a buffer battery, also with a modified generator setup to allow for very rapid charging during driving. But I have a lot of experience using a similar 600w setup, which kept me running permanently without shore power for much of the year, with absolutely no problems. These 600w was sloped - so more efficient than flat panels.

I know I waste a lot of power during sunny days, but that's not the point. The point is to get at least some charging during a cloudy week.
 
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Thanks for reply , I was asking as I have 900ah wet batteries and was thinking of maybe 600w to 1040 w panels seen as a kit on a solar site , and was wondering about balance between the components .

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Urs4_2008

Urs4_2008

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Thanks for reply , I was asking as I have 900ah wet batteries and was thinking of maybe 600w to 1040 w panels seen as a kit on a solar site , and was wondering about balance between the components .
(y) There's a few different considerations regarding this.
  1. What charge rate does your current wet batteries support? A regular wet battery could range from 0.1-0.2C charge rate, meaning in your case a possible maximum charge rate of somewhere around 90 to 180 amps. I would check battery documentation and select a regulator which supports a soft limit.
  2. Do you want to charge as much as possible during less than optimal conditions, if so go with as much as you can get, and deploy a soft limit of charging in accordance with battery documentation.
Anyways, 1040 watts will possibly yield about 90 amps maximum, which can occur when batteries are about empty (11,7 volts) and the solar conditions are optimal. If your batteries are not too strange, this will generate a maximum charge rate of about 0.1C, which most wet lead acid batteries would find acceptable.

Just my opinions based on my experience and knowledge :)

http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
 

Freespirit1

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From your Panel data sheet I would suggest you would be ok with all in series 8x17.7= 141.6v max - without volt drop - good margin for a 150v input controller. The controller would never see an open voltage of course which would be 8 x 21.2= 169.6v but don’t catch hold of the ends eh! :)
 
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Urs4_2008

Urs4_2008

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From your Panel data sheet I would suggest you would be ok with all in series 8x17.7= 141.6v max - without volt drop - good margin for a 150v input controller. The controller would never see an open voltage of course which would be 8 x 21.2= 169.6v but don’t catch hold of the ends eh! :)

I wasn't sure about this. What about when the batteries are full, and the charge controller lifts off a lot. Would'n the panels slowly rise to their nominal voltage? I haven't testet, but that was my understanding. When I measure a single panel out in the sun, I get close to nominal voltage, that's why I opted for this configuration :)

When sunny conditions reappear, I will measure the voltage when batteries are full (which they almost always are)

It's good to get a jolt from time to time, keeps the ticker ticking ;)

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Freespirit1

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E4758051-4E9D-4AFF-A04C-8DD8E28B48F7.png
I wasn't sure about this. What about when the batteries are full, and the charge controller lifts off a lot. Would'n the panels slowly rise to their nominal voltage? I haven't testet, but that was my understanding. When I measure a single panel out in the sun, I get close to nominal voltage, that's why I opted for this configuration :)

When sunny conditions reappear, I will measure the voltage when batteries are full (which they almost always are)

It's good to get a jolt from time to time, keeps the ticker ticking ;)

They may - just may? rise to their max power voltage (Vmp) given on your panel as 17.7v each as that is probably their guaranteed voltage and might go up a very small amount more but some system volt drop will likely negate that - and that’s will optimum Sun position :)

I don’t know if your present controller has a facility for a remote display / parameter adjustment ? if it does it might be an idea to get one so you can see the performance at any given time. If your getting a different controller then ensure it either has an onboard display or remote facility ( preferred as you can view from inside your MH ) which I have done with mine.

You won’t have seen this photo of my panels posted on a different thread here - they are CIGS technology 3mm thick - you walk all over them and very easy to clean but tend to stay pretty clean anyway :)

Needless to say yours are pretty robust but don’t walk on them will you - semi flexible are prone to hairline cracking as you can’t bend the silicone cells - you may have experienced the odd creaking noise when handling yours? :)
 
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Urs4_2008

Urs4_2008

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View attachment 217482

They may - just may? rise to their max power voltage (Vmp) given on your panel as 17.7v each as that is probably their guaranteed voltage and might go up a very small amount more but some system volt drop will likely negate that - and that’s will optimum Sun position :)

I don’t know if your present controller has a facility for a remote display / parameter adjustment ? if it does it might be an idea to get one so you can see the performance at any given time. If your getting a different controller then ensure it either has an onboard display or remote facility ( preferred as you can view from inside your MH ) which I have done with mine.

You won’t have seen this photo of my panels posted on a different thread here - they are CIGS technology 3mm thick - you walk all over them and very easy to clean but tend to stay pretty clean anyway :)

Needless to say yours are pretty robust but don’t walk on them will you - semi flexible are prone to hairline cracking as you can’t bend the silicone cells - you may have experienced the odd creaking noise when handling yours? :)

Very nice setup! Do you have different wattage cells in series? It seems the panels are different sizes.

I believe the Vmp is the guaranteed voltage at maximum power. In this condition I'm sure the Victron MPPT 150/70 has no problems with the ~142 volts. I will check voltage at the first sunny day to figure this out. Anyways, at 70-80 volts it's not a problem to handle the maximum ~12 amps running from the roof electrical box down to the controller. The calculated voltage drop is less than 1% (~0.7%) which is well below the 3% mark, in this condition (maximum power delivery). In normal conditions i figure I'll get about 7 amps at 70 volts, giving about 0,4% inefficiency in my setup. But summer is coming and time will tell.

Never heard any creaking, and the panels are 3mm thick. You're supposed to be able to step on them, but I never have the need to walk on my roof, so not an issue. Time will tell about the rest of the quality, they're not the most expensive cells :)

The Victron MPPT controller has a bluetooth app with lots of configuration, data history etc.

Not much sun now... :(

IMG_3097.PNG
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IMG_3100.PNG
 
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Urs4_2008

Urs4_2008

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Actually, I think I answered my own question. It seems it is like I said. When the batteries are fully charged, the voltage in the setup nears the open circuit voltage for the 4 panels in series. This would result in a maximum voltage of 170 volts if all were to be configured in series. That's a bit on the high side.

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They may - just may? rise to their max power voltage (Vmp) given on your panel as 17.7v each as that is probably their guaranteed voltage and might go up a very small amount more but some system volt drop will likely negate that - and that’s will optimum Sun position :)
If there is no load on a solar panel, the voltage will rise to its maximum (open circuit) voltage, which is considerably more than the maximum power voltage - more like 35 volts, not 17.7 volts.

As you draw more load current out of it, the voltage falls as the current increases. There is an optimum point, where the power is a maximum. A Maximum Power Point (MPP) controller will control the load current so that it is always working at the maximum power point.

When the controller doesn't require the maximum power, it reduces the load current, so that the solar panel voltage rises again. When the batteries are fully charged, and there's no load current required, the panel voltage will be just about back to its maximum (open circuit) voltage again.

Because the current is zero, the power (voltage x current) from the solar panels will be zero.
It's good to get a jolt from time to time, keeps the ticker ticking ;)
Whenever voltages of more than about 50 volts are present, you need to take precautions against electric shock. It's not commonly discussed in motorhome circles because the panels are nearly always wired in parallel.

This installation, with two strings of 4 panels, is more like a domestic solar array, and should be treated with the same care.
 
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Urs4_2008

Urs4_2008

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If there is no load on a solar panel, the voltage will rise to its maximum (open circuit) voltage, which is considerably more than the maximum power voltage - more like 35 volts, not 17.7 volts.

As you draw more load current out of it, the voltage falls as the current increases. There is an optimum point, where the power is a maximum. A Maximum Power Point (MPP) controller will control the load current so that it is always working at the maximum power point.

When the controller doesn't require the maximum power, it reduces the load current, so that the solar panel voltage rises again. When the batteries are fully charged, and there's no load current required, the panel voltage will be just about back to its maximum (open circuit) voltage again.

Because the current is zero, the power (voltage x current) from the solar panels will be zero.

Whenever voltages of more than about 50 volts are present, you need to take precautions against electric shock. It's not commonly discussed in motorhome circles because the panels are nearly always wired in parallel.

This installation, with two strings of 4 panels, is more like a domestic solar array, and should be treated with the same care.

Yes, pretty much like I mentioned, and what the graph from the app shows.

Yes, more volts are more dangerous. It's all well protected, and I'm not a novice in this area :)
 
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Urs4_2008

Urs4_2008

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forgot to ask,, what storage capacity do you have ?

The Hymer Exsis-I is designed to be light weight, and has stated 660 kilos as cargo capacity. That is included a driver, and with some diesel, water and gas. But not including cutlery, food, drinking water, TVs, ipads, clothes, skis etc. So it's a tight fit. But i will drop heavier things before number of panels, which are quite light. And during summertime I do not bring the heavy power cable (25 meters heavy duty). :)

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Freespirit1

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If there is no load on a solar panel, the voltage will rise to its maximum (open circuit) voltage, which is considerably more than the maximum power voltage - more like 35 volts, not 17.7 volts.

As you draw more load current out of it, the voltage falls as the current increases. There is an optimum point, where the power is a maximum. A Maximum Power Point (MPP) controller will control the load current so that it is always working at the maximum power point.

When the controller doesn't require the maximum power, it reduces the load current, so that the solar panel voltage rises again. When the batteries are fully charged, and there's no load current required, the panel voltage will be just about back to its maximum (open circuit) voltage again.

Because the current is zero, the power (voltage x current) from the solar panels will be zero.

Whenever voltages of more than about 50 volts are present, you need to take precautions against electric shock. It's not commonly discussed in motorhome circles because the panels are nearly always wired in parallel.

This installation, with two strings of 4 panels, is more like a domestic solar array, and should be treated with the same care.

Yep - that’s how I see it too - with a remote display you can see all those various conditions and current/ voltage values - however my panels in practice never rise over and above their total maximum power voltage and our friend here from Norway’s panels state 21.2v open circuit voltage not 35v :)
 
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Urs4_2008

Urs4_2008

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Yep - that’s how I see it too - with a remote display you can see all those various conditions and current/ voltage values - however my panels in practice never rise over and above their total maximum power voltage and our friend here from Norway’s panels state 21.2v open circuit voltage not 35v :)
The data show 85 volts => 21.2 Pr panel, Yes.
 

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I wasn't sure about this. What about when the batteries are full, and the charge controller lifts off a lot. Would'n the panels slowly rise to their nominal voltage? I haven't testet, but that was my understanding. When I measure a single panel out in the sun, I get close to nominal voltage, that's why I opted for this configuration :)

When sunny conditions reappear, I will measure the voltage when batteries are full (which they almost always are)

It's good to get a jolt from time to time, keeps the ticker ticking ;)

I would email Victron and ask their view on the maximum input voltage. It might be tolerant of over-voltage but it might not be. :) A panel voltage of 18.75 volts could easily be seen and 8 * 18.75 = 150. The MPPT controller doesn't run all the time at the maximum power voltage. If it needs less power, which will often be the case, it will allow the panel voltage to increase to reduce the input power. In my experience Victron are very good at replying in English to emails. I would ask them what they think. An alternative approach would be to link each bank of 4 to a separate controller. This will reduce the effects of shading. :)
 
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Urs4_2008

Urs4_2008

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I would email Victron and ask their view on the maximum input voltage. It might be tolerant of over-voltage but it might not be. :) A panel voltage of 18.75 volts could easily be seen and 8 * 18.75 = 150. The MPPT controller doesn't run all the time at the maximum power voltage. If it needs less power, which will often be the case, it will allow the panel voltage to increase to reduce the input power. In my experience Victron are very good at replying in English to emails. I would ask them what they think. An alternative approach would be to link each bank of 4 to a separate controller. This will reduce the effects of shading. :)

Like I said, it's not really an issue to configure all the panels in series. 70-80 volts with maximum 12 amps is perfect :)

Ideally, each panel could have its own controller (like some house solutions), but in a motorhome this would be impractical. o_O

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scotjimland

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The Hymer Exsis-I is designed to be light weight, and has stated 660 kilos as cargo capacity. That is included a driver, and with some diesel, water and gas. But not including cutlery, food, drinking water, TVs, ipads, clothes, skis etc. So it's a tight fit. But i will drop heavier things before number of panels, which are quite light. And during summertime I do not bring the heavy power cable (25 meters heavy duty). :)

thank you..

I should have said 'battery' storage capacity .. but you have answered that question

.. cheers
 
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