Your post is confused and confusing, please consider rewriting it and also telling us what the BMpro things are.

If you wish to run Amateur Radio from the van's inverter generated 240V you will need to be *very* careful in regard to EMI generated by your system, is the inverter, and all other gear, qualified to IEC61000-6-3?

It's helpful if you provide links to obscure items:

BatteryPlus35

The first thing you need to do is check the voltage produced by your solar panels as the BP35 has a maximum input voltage to its solar controller of 25V. Even if your panels are below that you will not be able to wire them in series - which is not a major issue but needs to be considered.

The next issue is that your 640W of solar can produce about 50A but the BP35 is limited to 30A so it can never use that spare 20A.

Next: the BP35 can charge batteries with a maximum of 30A so if your 400Ah of lithiums is 50% depleted it will take 7+ hours of full sun to recharge them.

Q1 answer: yes, you can but it's not a good way to do things. I suggest leaving the BP35 to look after the van's battery and purchase a new quality MPPT controller with a 100V/50A capability = not cheap but it'll work well.

Also connect the batteries as 24V and use a 24V inverter.

Yes, you can take 12V from the batteries for the radio but it's not a good way to do it. Apart from the voltage drop between battery and radio my guess is there will be one hell of a lot of conducted RF noise at the battery terminals. Better to have a separate battery which is used solely for the rado and recharged as necessary, that's what I do. I suspect you'll have issues with radiated RF from the inverter et al in any event.

Q2 answer: Yes *BUT* *NEVER* connect mains 240V (eg caravan park) and the inverter to the van's system else your inverter will be instantly destroyed. I do this and have a cable from the inverter which has a 15A female connector which I connect to the van's 240V input, doing it this way makes it impossible to accidentally connect mains and inverter simultaneously. 

VK2FJW wrote:

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>4 times 8.21 = 32.84 maximum, is this how they are wired?

They need to be wired to the solar controller in parallel.

>Looks like I bought 2 panels to many, 4 is too much for the BMPRO.

Not really; keep in mind that they will often not be producing their maximum output.

 

>Your answer to Q1 is overkill

No, it is the correct answer and the proper way to do things; whether you choose to accept that is another matter.

You need to look at the output of the controller. My 20 amp controller can output up to 11.3 amps from 120 watts of solar which typically runs at about 127 watts but up to 137 watts with water cooling.

So 11.3 amps / 120 x 160 x 4 = 60.2 amps.

If you get a 30 amp controller you will be missing out on a lot of amps. Further more you will possibly ruin the controller as it will at it limit or over its limit most of the time.

I had a 10 amp controller but 10 amps was the maximum output, so replaced it with a 20 amp output model.

The MPPT will will adjust the volts to output as many amps as possible. So if the batteries are somewhat flat the MPPT will charge at a lower voltage & therefore you get more amps.

So if the MPPT is charging at 12.6 volts, you will get 50.7 amps out of your 640 watts of panels midday.

Earlier in the morning, let's say at 70% due to the angle, you can sketch various scenarios out on a bit of paper to calculate percentages, so then 35.5 amps.

Your controller will be ok in the morning, but probably best to put in an isolation switch to turn off a panel or two midday. Actually of you switch all four it would be useful for tracing faults & testing individual panels.

I would also mount it so it has really good cooling at it will have no headroom with the wattage of panels you have.

You will probably find it will throttle down for every degree above 40°C temperature to protect itself & turn off at 60°C. So high ambient temperature, pushing out maximum amps, poor air circulation, it will throttle down. I have stuck on additional heatsinks on my controller for improved cooling. A bit of overkill in my situation as I am nowhere near maximum output. But why not. You could stick a Noctua fan on it for additional forced cooling.