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Camper Van Solar System Questions

DoctorBrucey

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Joined
May 14, 2024
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13
Location
Sheffield, UK
Hey everyone,

I'm quite new to this, so bear with me! Currently designing my solar system for my van, which will be two 100W Renogy panels and this DC to DC / MPPT Controller unit also from Renogy.

My idea was to wire them in series, but looking at the panels' VOC (24.3V) and the controller's Max. Solar Input Voltage (50V) I'm worried that wiring in series will leave me too close to the controller's max input voltage.

Would you recommend wiring in parallel instead? And if so, am I correct in saying that I won't need an in-line fuse? As the panels' Short Circuit Current is 5.21A, and Maximum Series Fuse Rating is 15A (so wiring in parallel would be 10.42A ISC which is < 15A)

Still trying to wrap my head around all of this, so would appreciate any help! Thank you.
 
Hey everyone,

I'm quite new to this, so bear with me! Currently designing my solar system for my van, which will be two 100W Renogy panels and this DC to DC / MPPT Controller unit also from Renogy.

My idea was to wire them in series, but looking at the panels' VOC (24.3V) and the controller's Max. Solar Input Voltage (50V) I'm worried that wiring in series will leave me too close to the controller's max input voltage.

Would you recommend wiring in parallel instead? And if so, am I correct in saying that I won't need an in-line fuse? As the panels' Short Circuit Current is 5.21A, and Maximum Series Fuse Rating is 15A (so wiring in parallel would be 10.42A ISC which is < 15A)

Still trying to wrap my head around all of this, so would appreciate any help! Thank you.
Looks correct.

Skip the renogy MPPT. I have 4 sitting on the junk shelf. Not because they failed, because the app is garbage and the MPPTs are weak.

Spend a little more for a solid victron with Bluetooth. Better and free app. Better voltage range and future expansion.
 
Looks correct.

Skip the renogy MPPT. I have 4 sitting on the junk shelf. Not because they failed, because the app is garbage and the MPPTs are weak.

Spend a little more for a solid victron with Bluetooth. Better and free app. Better voltage range and future expansion.

Great, glad to know I'm not totally off!

Oh really? I was hoping to save money / wiring by having the DC to DC combined with the MPPT, instead of having two different units. Would you say it's worth the extra cost?

Can always help take one of the Renogy units off your hands if they're just collecting dust... hah!
 
me too close to the controller's max input voltage.
In temperatures below 25C panel volts increase, 3 to 4% for every 10C. Thus you will exceed the controller limit.
Renogy panels are OK but it's hit and miss with their other products and technical support is very poor.
With two panels in parallel you dont need a fuse, as the current can never exceed the fuse rating. If you have 3 or more panels or panel strings, in parallel , fuses are needed.

Unless you already have the Renogy unit, consider alternatives. Seperate units perform much better then combined devices.
Solar controler, ( will work with your two panels in series).
Dc to DC charger,
 
Gotta mostly agree. Run the Renogy as a DC-DC only and get an independant SCC for the panels. The cost difference between a 20a that will utilize both panels and a 40a that lets you expand later isn't much and will be worth it.

Personally not a Victron fan, but there are many, many brands and models that will turn solar DV into battery DC for less money.
 
In temperatures below 25C panel volts increase, 3 to 4% for every 10C. Thus you will exceed the controller limit.
Renogy panels are OK but it's hit and miss with their other products and technical support is very poor.
With two panels in parallel you dont need a fuse, as the current can never exceed the fuse rating. If you have 3 or more panels or panel strings, in parallel , fuses are needed.

Unless you already have the Renogy unit, consider alternatives. Seperate units perform much better then combined devices.
Solar controler, ( will work with your two panels in series).
Dc to DC charger,

Thanks that's very helpful. So you'd recommend both those units instead? Would those exact models work for my two 100W panels (could I go less than the 100/20 model for example?) and my requirements for a DC to DC charger?

Not sure which specs I need to check for the DC to DC charger. I'm in a 2014 MWB Fiat Ducato.

Also, if I'm not using a single unit for DC to DC and MPPT, will I need a Lynx Distributor?
 
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Would those exact models work for my two 100W panels (could I go less than the 100/20 model for example?) and my requirements for a DC to DC charger?
Two 100 watt panels, via a MPPT controller under ideal conditions, will deliver aroung 15 amps into the battery. In the Victron range you have the 75/15 at £58 or the 100/20 at £78. I suggested the 100/20 as it will operate well within its range and gives the possibility of adding a 3rd panel for an upgrade. ( however if cost us an option the 75/15 will be OK).
Regarding the DC charger, the Orion 12 12 30 works well, ( I have one on my van) and is within the acceptable loading on the vehicle charging system.
The advantage of the better engineered Victron chargers is that , via the phone app, the units can be setup for any battery type including user settings. ( with some batteries the default settings in chargers cause issues and modification of the charge voltages resolves the problem).
The app also shows battery state and data on solar power generated ( over the last 30 days).
You don't need the Lynx distributer in a small setup, the output of the solar controller and DC to DC charger onnect to the house battery via suitable fuses . Use this near the house battery,
Use a 30 amp Midi fuse for the solar controller and a 50 amp Midi fuse for the DC to DC charger. Use 6mm2 cable for the controller and 10mm2 for the charger .

Mike
 
reason to use the non-isolated DC to DC instead of the isolated?
You can use either but since the house, leasure battery needs to be connected to van metal/ chassis both the starter and house battery have the negative common.

negatives of the MPPT controller / DC to DC charger to the bus bar at the bottom?
Yes, as will the negative of the DC fuse box for accessories , suggest this fuse box, 6or 12 way, as there are negative connection points for accessories negative.
the 4mm cable that comes with the solar panels okay for connecting to the MPPT
Yes, for the lowish current there is no advantage in using 6mm2. A small volt drop on the input side of the controller is acceptable, on the output side, to the battery, its more critical, as the controller needs to 'see' battery voltage accuratly. Thus mounting the controller as near as practical to the battery is recomended.

When connecting to the vehicle battery you can use or add, ( if its not installed) a 50 amp fuse in the position shown,
Screenshot_20240102-152212_Chrome~2.jpg

A few questions,

What batteries are you Intending to use ?
Is the vehicle a van conversion or a standard motorhome with an Installed electrical system.?
 
You can use either but since the house, leasure battery needs to be connected to van metal/ chassis both the starter and house battery have the negative common.


Yes, as will the negative of the DC fuse box for accessories , suggest this fuse box, 6or 12 way, as there are negative connection points for accessories negative.

Yes, for the lowish current there is no advantage in using 6mm2. A small volt drop on the input side of the controller is acceptable, on the output side, to the battery, its more critical, as the controller needs to 'see' battery voltage accuratly. Thus mounting the controller as near as practical to the battery is recomended.

When connecting to the vehicle battery you can use or add, ( if its not installed) a 50 amp fuse in the position shown,
View attachment 215593

A few questions,

What batteries are you Intending to use ?
Is the vehicle a van conversion or a standard motorhome with an Installed electrical system.?

Okay brilliant. I’ve tried to look up the best way to earth the leisure battery the van metal. Looks like just scratching off the paint and putting in a nut and bolt… does that sound right? Bit worried about rust with that exposed metal, but will do it if need be.

Looking to use this 280ah lithium battery: https://uk.eco-worthy.com/collectio...yq7cgS0pzbDezW87FSmqYEd1Y88xJI5RoCIvwQAvD_BwE

And it’s a converted van, not motorhome.
 
to look up the best way to earth the leisure battery the van metal.
There are built in welded stud/ captive nut points, near the battery, follow the negative cable. Under the plastic doorstep , inside the rear pillars. Also the tie down points can be used if you remove the paint. Use a ''star' washer on the eye termination. There is no issue with corrosion inside the van. If you make a new 'hole' use a bolt with nuts and washers, not a self tapper.
280ah lithium battery
Advise against. There is no Bluetooth so you cannot 'see' what's happening inside the battery. There is also no low temperature protection, you damage the battery if you charge below 0C. Support from this company is nonexistent.

Recomend Fogstar Drift, 230Ah or 280Ah,
Although more expensive, you have Bluetooth communication and self heating for charging below freezing. The company have excellent support should you need. Fogstar is a UK company that uses top grade cells, EVE, and quality management control circuit, BMS, from BYD.

More questions,
It's a larger battery than I expected with the modest 200 watts of solar. Of course it depends on your loading and expected use. Its no good having a large battery if you cannot replace the power used.

What are your expected DC loads, inverter? Compressor fridge?
Will, you have AC, mains charging?
What 'off grid' period do you expect with your usage ?

Mike
 
There are built in welded stud/ captive nut points, near the battery, follow the negative cable. Under the plastic doorstep , inside the rear pillars. Also the tie down points can be used if you remove the paint. Use a ''star' washer on the eye termination. There is no issue with corrosion inside the van. If you make a new 'hole' use a bolt with nuts and washers, not a self tapper.

Advise against. There is no Bluetooth so you cannot 'see' what's happening inside the battery. There is also no low temperature protection, you damage the battery if you charge below 0C. Support from this company is nonexistent.

Recomend Fogstar Drift, 230Ah or 280Ah,
Although more expensive, you have Bluetooth communication and self heating for charging below freezing. The company have excellent support should you need. Fogstar is a UK company that uses top grade cells, EVE, and quality management control circuit, BMS, from BYD.

More questions,
It's a larger battery than I expected with the modest 200 watts of solar. Of course it depends on your loading and expected use. Its no good having a large battery if you cannot replace the power used.

What are your expected DC loads, inverter? Compressor fridge?
Will, you have AC, mains charging?
What 'off grid' period do you expect with your usage ?

Mike
Okay, will have a look in the rear pillars as that's where I'm planning to put my leisure battery. Otherwise, I'll just create one myself.

Fogstar looks good, but as you said definitely more expensive. I wanted to go for 230-280ah, as I'm planning to sometimes use the van as a 'work from home' station. I was initially going to skip solar completely, but figured to make the extra investment for 200W (all I can fit on my roof). So the large battery was to see me through a day or two of working on my laptop in the van.

My plan is to skip AC, as the only thing I need charging is my laptop on a 61W USB-C charger (not other AC appliances). So was going to keep it simple and cheap and just use an inverter like this when I need to.

Am planning to never stay formant for more than 2-3 when using this 'work from home' set up, so would top up anything the solar can't with the DC to DC charger when driving between locations.

In terms of DC loads, I'll be using a handful of LED lights, diesel heater, water pump, USB sockets, cigarette lighter socket (for laptop / inverter), MaxxFan Deluxe, and most likely this router for WiFi. Trying to keep it simple.
 
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You will get more power out of your USB socket if you use a 24 volt system instead of 12 volt.

The higher end USB ports will auto adapt to your phone charge rate capability by increasing the voltage from the traditional 5 volts up to ~ 19 volts if the input voltage to it is high enough. This would allow skipping the inverter completely.

For a lot of vans, ( at least the ones sold here in the US, the solar panels can be mounted cross wise and are a good fit if the panel is a bit longer vs the short 100 watt ones. A good target length here is ~ 1500mm long.

Most DC appliances are available in 24 volt or dual 12 / 24 volt, for example refrigerator, led lights, diesel heater, etc.

Most of the DC fuse blocks and breakers on the market are dual 12 / 24 volt rated, so the same exact components.

The few that are not can be powered via a DC - DC converter.
 
I'll be using a handful of LED lights, diesel heater, water pump, USB sockets, cigarette lighter socket (for laptop / inverter), MaxxFan Deluxe, and most likely this router for WiFi
Your setup is fine on a 12v system, there is no need to consider 24 volts. The solar won't contribute too much in winter, see how things work out and add a mains charger if required.
Regarding the battery, it's very important to have the low temperature protection, ( or heating), and the Bluetooth alows you to 'see' how 'full' the battery is and what power your acessaries are using.
 
Your setup is fine on a 12v system, there is no need to consider 24 volts. The solar won't contribute too much in winter, see how things work out and add a mains charger if required.
Regarding the battery, it's very important to have the low temperature protection, ( or heating), and the Bluetooth alows you to 'see' how 'full' the battery is and what power your acessaries are using.
Thanks Mike, I'll stick to 12v.

Would you suggest I start with a smaller battery, then see if 230-280ah is needed? Or does my set up sound suitable for 230-280? I've done all of the calculations for amp hours with my devices, but hard to conceptualise it in day-to-day living. Cheers.

Sounds like Fogstar is worth it for the monitoring purposes (as would need to be something like this to get the same thing with the cheaper battery, correct?)
 
same thing with the cheaper battery, correct?)
The smart shunt is worth installing with any battery but does not show what's going on inside the battery. A battery with a Bluetooth BMS will show exactly what is happening with the 4 cells that make up the battery, such as each cell voltage, cell temperature , indicate that the battery is charging or discharging, battery SOC. If a protection event occurs it indicates what happened, for example, the battery charge volts was too high. Also with a suitable app its possible to modify the protection levels, for example the overcurrent protection set at 200 amps is rather high for your modest application.
With the Bluetooth communication impending possible battery faults are easy to see, this enables correction procedures, for example changing the charge volts. In the very rare worst case, a battery fault can be diagnosed more easily making any warranty claim painless with companies like Fogstar in the UK .
(Warranty claims with Renogy or Eco worthy are extremely difficult and time consuming to process, technical help is almost non existant and any replacement you are extremely lucky to get may not be in UK stock, involving shipping problems. )


fuse sizes to use for the DC to DC and MPPT?
You know the expected current and specification of the unit. Use suitable cable for the current and ensure any volt drop is acceptable,


If you go to the cable section of 12v Planet the maximum current rating of each size of cable is shown. Often in 12 volt systems you use a 'fatter' cable than the current specification to get a reduced volt drop.

The DC to DC charger from Victron is a nominal 30 amp unit. The fuse must be higher than 30 amps to prevent false trips, select 125 to 150 %. ( in practice the Orion current exceeds 30 amps on the input and output so a 50 or 60 amp fuse is recomended by Victron.

Once the fuse is closed check the cable is rated for this current.

The MPPT is rated at 20 amps, so a 30 amp fuse is needed , a 6mm2 cable can carry 50 amps. Checking for volt drops , assuming a 1 meter run to the battery, using the calculator for 20 amps, volt drop 0.13 volts. Since with 200 watts the current will be lower than 20 amps a volt drop of around 0.06 volts is OK.

Regarding the Video help from Greg, his 12v advice is good but the inverter and AC side is sometimes non complianent ( Greg and myself have had email communication discussing some issues).

Typical failures in camper conversions, cables too small, no or incorrect fusing, fuses in the wrong place, house battery negative and AC protective earth not connected to van metal/chassis/frame, batteries not secure clamped. The most dangerous failures are in the AC circuits and inverters with no or incorrect electric shock protection. There are standards that professional converters legally have to comply with, many DIY you tube 'experts', do not. DIY electrical work on a van conversion can be carried out in the UK without Inspection or professional input
 
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