Wiring Solar Panels advice please? (1 Viewer)

[Jeniflower]

Hi,

I wonder if anyone can explain the best way to resolve, or had experience of same?
Am planning to install simple solar power system to fiat conversion van (weinsberg carabus), to provide off grid for fridge, water pump & phone charging etc.

Currently system automatically defaults to engine battery when driving, mains when plugged in and then leisure battery automatically. Some systems I have looked at wire solar panels (via control unit) to leisure battery and engine battery - some to leisure battery only.

I don't imagine I will need to charge the engine battery from solar, but am wary of installing to leisure battery only as this may 'mess with' the installed default system. I am concerned about whether the system will know to revert from solar to mains to engine when switched on? and how this would all be regulated? I'm worried about damaging the system already fitted, and what the advantages or otherwise of wiring both batteries is? And have confused myself.........................

Any advice gratefully appreciated!

Thanks,

Jennie

 

[PhilandMena]

It might help others to help you if you tell them what system you actualy have installed.

 

[Jeniflower]

Thanks for reply PhilandMena,

I don't know if the system has a name but is standard leisure battery, engine battery set up fitted as standard to weinsberg carabus? Just not sure of benefits of wiring to both batteries or just the leisure one and using with a manual switch? I don't know if there is more information that I need to make sure all batteries are safe? I am learning all this on a very steep curve Maybe is obvious and I just don't understand.

Thanks for anyone's time on this,
Much appreciated

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[pappajohn]

Solar is ON all the time the sun shines regardless of other charging systems... It will have no I'll effects with battery.
The solar is no different than your onboard charger or alternator except in efficiency and appearance.... Its still a charging system.
Unless you have a compressor fridge it won't run for long on battery and shouldn't be connected as such. 12v is provided ONLY when the engine is running. Run it on gas if 230v hookup isn't available.

 

[GeoffnDee]

There is no problem wiring the solar panel to the leisure battery (via a solar controller) and this is often the way it is done, the benefit of some of the solar charge going to the starter battery either with a split charge controller or a battery master which sends a trickle charge from the leisure battery/solar panel into the starter battery (Vanbitz sell them ,for this purpose) is that if in storage, without hook up , the starter battery will go flat in a few weeks due to the van electronics etc draining it. A small charge to the starter battery by either method will overcome this possible problem.
Depending as to the type of system fitted to your van some can be wired into the van PSU and it will divert the solar power to whichever battery needs it , but not all systems do this.
As @pappajon has said you will not be able to run the fridge from the solar if it is a 3 x way one (gas , 12v ,230v) but it may be possible ,in sunlight ,with a compressor type.
You have not said what size of solar panel (s) you intend to fit but I have a single 100 watt one and that keeps my batteries topped up Ok but you may need a lot more if you need to use many electrical items.
If you are not sure and you give your location ,someone in your area may be able to recommend a Motorhome solar fitting company who would be able to sort out the best system for your type of van.

 

[Itsmcb]

Hi Jenny. Whatever solar panel you fit will need a Solar controller fitted between the the panel and your leisure battery. It is this controller that works out how much electricity to send to the battery. It will do this even if you are driving and charging the leisure battery from your alternator OR on mains hook up and charging via your vans built in mains charger. This means everything works together and you don't need to think about switching anything on or off.
Some solar controllers have two outpours and can charge both leisure battery and starter batteries at the same time if required.

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[autorouter]

Am planning to install simple solar power system to fiat conversion van (weinsberg carabus), to provide off grid for fridge, water pump & phone charging etc.

The largest demand on the battery when off-grid will be the fridge. How you deal with this depends on what kind of fridge. There are two types fitted in motorhomes. One type is like your normal house fridge, with a motor and a compressor that circulates the coolant. The other type is a '3-way' fridge with no compressor that works from gas, 240V electric and 12V electric.

The 3-way type is not very efficient on 12V, and usually only works on 12V while the engine alternator is running. When parked without mains hookup, it works on gas.
So, which type of fridge is it, compressor or 3-way?

 

[Jeniflower]

Thanks so much to all for excellent advice, fridge is electric only so will be main user of solar when off grid.
it’s now clear that I just need to buy the correct solar controller and it should all work fine, well I’ll try that and see if it works for me,
Cheers everyone, enjoy your week!

 

[autorouter]

Regarding the solar panel power, 200W is a rather minimal if you are running a compressor fridge, and 300W is a bit more comfortable. 300W is 25A at 12V, so you would need a solar controller capable of at least 25A.

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[Vikdikdok]

Don't bother with a pulse modulation controller - go for MPPT (don't skimp get a VICTRON !

 

[Jeniflower]

Victron MPPT 25 amps plus it is!

Let there be light! (and cold drinks

Thanks again all -

 

[Vikdikdok]

Victron MPPT 25 amps plus it is!

Let there be light! (and cold drinks

Thanks again all -

that’s the right choice

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[andyshrimpton]

Here is a good youtube channel to watch

 

[SDF986s]

hi all, new member to the forum and I have a very similar , if not the same question as Jeniflower

I have what I would term a typical setup, 240V hookup and a 12V leisure battery. When hooked up to 240V it will charge the leisure battery, provide power to the fridge (3 way) and a couple of 13A sockets

I assume the water pump and lights are still fed from the 12V system and the 240v hookup keeps the battery charged.

If i add a solar panel with a controller can I wire the battery output from the controller directly to the leisure battery in parallel to the existing feeds?

Is there any risk of damaging the existing charging circuit?
OR
Am I better off installing a 2 way switch so leisure battery either takes feed from the existing setup OR the solar panel?

any advice gratefully received

 

[Richard n Ann]

hi all, new member to the forum and I have a very similar , if not the same question as Jeniflower

I have what I would term a typical setup, 240V hookup and a 12V leisure battery. When hooked up to 240V it will charge the leisure battery, provide power to the fridge (3 way) and a couple of 13A sockets

I assume the water pump and lights are still fed from the 12V system and the 240v hookup keeps the battery charged.

If i add a solar panel with a controller can I wire the battery output from the controller directly to the leisure battery in parallel to the existing feeds?

Is there any risk of damaging the existing charging circuit?
OR
Am I better off installing a 2 way switch so leisure battery either takes feed from the existing setup OR the solar panel?

any advice gratefully received

Yes. Most are just on the battery in parallel with the mains charger and alternator. Ours is like this and the solar controller stops charging when the engine is running, is comes back a few minutes after the engine has gone off.

Install a switch on the positive between solar controller and solar panel, that's handy to have

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[Richard n Ann]

hi all, new member to the forum and I have a very similar , if not the same question as Jeniflower

I have what I would term a typical setup, 240V hookup and a 12V leisure battery. When hooked up to 240V it will charge the leisure battery, provide power to the fridge (3 way) and a couple of 13A sockets

I assume the water pump and lights are still fed from the 12V system and the 240v hookup keeps the battery charged.

If i add a solar panel with a controller can I wire the battery output from the controller directly to the leisure battery in parallel to the existing feeds?

Is there any risk of damaging the existing charging circuit?
OR
Am I better off installing a 2 way switch so leisure battery either takes feed from the existing setup OR the solar panel?

any advice gratefully received

 

[autorouter]

All chargers, solar controllers etc have a diode (electrical one-way valve) on their output, so there is no risk of unwanted back-feeding. They all play nicely together. It is normal to just connect them all to the battery.

 

[tonyidle]

Underlying the questions is a concern that connecting another charging source to a battery might damage or affect the existing system. It won't. The battery will accept charging current from whichever source is supplying the higher voltage at any given time: other sources simply standby until they are able to contribute.

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[SDF986s]

all, thanks for all the responses, i did wonder if each type of charging circuit had protection diodes , good to have confirmation

 

[Marauder]

Some solar controllers have two outpours and can charge both leisure battery and starter batteries at the same time if required.

So should I be thinking about solar controllers with two outpours or some B2B / split charge relay device that I've been reading about frequently on MHF ?

 

[steveh57]

Simply , Solar controller i.e Victron with two ouputs to charge both leisure and starter batteries. A B2B or a SCR to charge leisure battery whilst the engine is running. Solar Controller with one output to charge leisure battery, starter battery topped up via a seperate device i.e Vanbitz Battery master

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[Marauder]

Simply , Solar controller i.e Victron with two ouputs to charge both leisure and starter batteries. A B2B or a SCR to charge leisure battery whilst the engine is running. Solar Controller with one output to charge leisure battery, starter battery topped up via a seperate device i.e Vanbitz Battery master

so people retro-fit B2B units - but I assume leisure battery would ALREADY be charged by a running engine as standard ?

 

[steveh57]

Some newer vans come with a B2B charger , older vans tend to have a Split Charge relay or a Voltage Senstive relay. The standard vehicle is designed to have the alternator top up the starter battery. The motorhome of course usually has an additional leisure battery(s) the split charge relay is activated when the engine is running and provides additional current/charge to the leisure. It provides charge according to the system resistance, once the batteries become towards full the current tails off, often to quite low levels thus charging maybe incomplete.

A B2B tricks the alternator into thinking the batteries are uncharged and makes it work harder, pulling as much power as it's designed for, the magic of a B2B is that it also steps up the voltage ( remember the SCR is only providing charge at constant voltage around 13.8V) to that required to charge the battery, you can then set the correct/specific charge profile according to the battery type whether it be AGM/Gel Lithium etc, all require a different charge profiles to become fully charged and also to maintain battery life/longevity with lead acid(s).

The B2B has become more popular since the advent of Lithium batteries which accept as much charge as is available until full, so in one instance with an SCR the charge input to the Lithium can overload the alternator and thus lead to premature failure . The other scenario is when a Lithium battery becomes full the current flow will suddenly cease, supplying charge after this will/may damage the Lithium battery although the incorporation of BMS should prevent this. The B2B gets round both these issues supplying a constant (safe ) charge current at the correct voltage determined by the profile selected and then stops charging

 

[autorouter]

Some newer vans come with a B2B charger , older vans tend to have a Split Charge relay or a Voltage Senstive relay. The standard vehicle is designed to have the alternator top up the starter battery. The motorhome of course usually has an additional leisure battery(s) the split charge relay is activated when the engine is running and provides additional current/charge to the leisure. It provides charge according to the system resistance, once the batteries become towards full the current tails off, often to quite low levels thus charging maybe incomplete.

A B2B tricks the alternator into thinking the batteries are uncharged and makes it work harder, pulling as much power as it's designed for, the magic of a B2B is that it also steps up the voltage ( remember the SCR is only providing charge at constant voltage around 13.8V) to that required to charge the battery, you can then set the correct/specific charge profile according to the battery type whether it be AGM/Gel Lithium etc, all require a different charge profiles to become fully charged and also to maintain battery life/longevity with lead acid(s).

The B2B has become more popular since the advent of Lithium batteries which accept as much charge as is available until full, so in one instance with an SCR the charge input to the Lithium can overload the alternator and thus lead to premature failure . The other scenario is when a Lithium battery becomes full the current flow will suddenly cease, supplying charge after this will/may damage the Lithium battery although the incorporation of BMS should prevent this. The B2B gets round both these issues supplying a constant (safe ) charge current at the correct voltage determined by the profile selected and then stops charging

There's also the smart alternator factor on newer MHs. A smart alternator is designed to charge up the starter battery to a minimum level (about 60% I think) then fill it up by switching on during braking and engine overrun. A split charge relay is not very good, because the leisure battery also ends up at the same fill level. That's not what you want when you arrive on an off-grid camping spot.

A B2B is a battery charger that takes its power from the alternator in the same way as for example the headlights or demister fan. It takes whatever the alternator throws at it, charges the leisure battery using the correct charging profile, and if necessary stops when full. As steveh57 says, it also limits the charging amps if necessary to prevent a lithium battery from overloading the alternator.

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[EML]

Just a thought on solar and 12V compressor fridges - I wouldn't get carried away with advice that you need 300W solar to run a fridge. A friend has 150W and has run a 12V fridge all through a 3-day wet festival, in the UK, in August, on just the solar and the leisure battery.

It's difficult to get good power consumption figures on 12V fridges, but I think the 'normal' van ones (with a Danfoss compressor) run at about 35W average. Modern mains fridges are much better - I've got a very cheap one, which should run at about half that, even after taking into account the inverter inefficiency (I haven't had it long enough to get a good figure yet). Getting an average 35W out of a 150W panel isn't too difficult, even in the UK.

 

[Otter Spotter]

Thanks for reply PhilandMena,

I don't know if the system has a name but is standard leisure battery, engine battery set up fitted as standard to weinsberg carabus? Just not sure of benefits of wiring to both batteries or just the leisure one and using with a manual switch? I don't know if there is more information that I need to make sure all batteries are safe? I am learning all this on a very steep curve Maybe is obvious and I just don't understand.

Thanks for anyone's time on this,
Much appreciated

You could do with taking pictures of the various electrical boxes you can find in the van, there will be a controller, a fuse box, possibly a B2B charger etc, without seeing these it’s difficult to know what you have and need. Not many people will have been inside a Weinsburg PVC

 

[Raul]

Just a thought on solar and 12V compressor fridges - I wouldn't get carried away with advice that you need 300W solar to run a fridge. A friend has 150W and has run a 12V fridge all through a 3-day wet festival, in the UK, in August, on just the solar and the leisure battery.

It's difficult to get good power consumption figures on 12V fridges, but I think the 'normal' van ones (with a Danfoss compressor) run at about 35W average. Modern mains fridges are much better - I've got a very cheap one, which should run at about half that, even after taking into account the inverter inefficiency (I haven't had it long enough to get a good figure yet). Getting an average 35W out of a 150W panel isn't too difficult, even in the UK.

That’s not how you work out your energy requirements. I have compressor fridges, one dometic and another like mobicool 40L used as freezer. Both compressors are identical digital variable speed and don’t have surge on start up. Also they slow down before switch of. However, when thermostat calls for cooling the compressor eats around 40-47w. That’s instant power not energy. I did measure the necessary per day. And that’s 300-400wh. That translates to 25-30ah needed to be put back in the battery daily. A solar in August even with overcast can do one to 3 sun hours even in UK. That’s a 100w solar can harvest 100wh to 300wh. That’s it, you can’t bend physics. Now move to September and harvest less, considerably less. Don’t take into account a good day, but work on average or possibly the least favourable situation. Then work out your necessary solar harvest. We live of grid for some time and I did fell in that trap on few occasions, under estimating the needs and over estimating the capability of equipment. Guess what, we learned the hard way. In a nut shell, a compressor needs a 300w solar as minimum balance, or find the energy elsewhere, driving with B2B, generator, or plug in ehu

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[CazPaul]

That’s not how you work out your energy requirements. I have compressor fridges, one dometic and another like mobicool 40L used as freezer. Both compressors are identical digital variable speed and don’t have surge on start up. Also they slow down before switch of. However, when thermostat calls for cooling the compressor eats around 40-47w. That’s instant power not energy. I did measure the necessary per day. And that’s 300-400wh. That translates to 25-30ah needed to be put back in the battery daily. A solar in August even with overcast can do one to 3 sun hours even in UK. That’s a 100w solar can harvest 100wh to 300wh. That’s it, you can’t bend physics. Now move to September and harvest less, considerably less. Don’t take into account a good day, but work on average or possibly the least favourable situation. Then work out your necessary solar harvest. We live of grid for some time and I did fell in that trap on few occasions, under estimating the needs and over estimating the capability of equipment. Guess what, we learned the hard way. In a nut shell, a compressor needs a 300w solar as minimum balance, or find the energy elsewhere, driving with B2B, generator, or plug in ehu

Very informative post, so all these PVCs sold with compressor fridges, if you haven’t got EHU, generator etc then they are not very good off grid unless you’ve got at least 300W of solar?

 

[Raul]

Very informative post, so all these PVCs sold with compressor fridges, if you haven’t got EHU, generator etc then they are not very good off grid unless you’ve got at least 300W of solar?

The aim is to be able to put that energy back every day, weather is by solar, B2B or ehu. If you haven’t got enough of these, then, day by day you will be eating into the reserve, and eventually will catch up with you screaming you are running on deficit. This is mostly for those occasional off grid with intermittent ehu. Also the consumption varies from one to another, Not one rule fits all. Some spend more on ehu and get away with little solar. What most get tricked by is, fair weather and good voltage. When fair weather vanishes, they think the battery is gone or to small.
To answer your question directly, off grid only yes, you will need at least 300w for a compressor only.

 

[Richard n Ann]

We had a compressor coolbox in Benidorm a few years ago, 150w panel was well over the top the battery suffered over night though as I had the coolbox set on -5°c and it ran a lot in the high ambient temperature.

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