Solar on our Motorhome Van, but not sure which controller to get ? help please

[Rixsta]

Hi

Was just wondering if anyone can help us, Ive been researching for a couple of months everything solar, I have lifelong interest in electronics and understand some things.
I recently found myself 3x 220w solar panels, they produce about 47v max each. In our self converted camper I am planning on running my laptop, an amplifier and a few lights etc

my problem is the van voltage is 12v and I would like to also charge my battery bank using a split charge relay or something similar so that the battery bank can be charged by solar and by the alternators power when driving.

This led me to think that a 12v system would be best...but I bet you can imagine the problem!
660w Panels
Divided by
12V
= 55A
which means I would need a very expensive Charge controller if going with MPPT.

So was just wondering what anyone here thinks ? any ideas of what I could do ? If I created a 24v system I would have a problem charging a 24v bank from the 12v van power!

Thanks
Rik

[Amy@altE]

You don't say how big your battery bank is. Trying to shove 55A into too small of a battery bank may be too much if it's a small battery bank.

[Mike90250]

It will be tough to step up that 12V to 24 for charging. But you now know one of the limits of 12v systems.
What's on the sticker on the back of the PV panels. Whats the # for Vmp and Voc ?

[Rixsta]

Thanks

Yes It seems pretty crazy to try and step up 12 to 24v so best to just stay with 12v but charge controller will cost more on 12v system. The one im looking at is a 60A morningstar.


The panels are

1580x808x35

210w

36v

5.83A working current

15.5kgs

and have 3 of them to go on van roof!

I do not have any batteries yet...

[Rixsta]

Amy@altE
Perhaps I can send the unused power to a load ? water heater ? So yes I need to find out how big battery bank is needede ? I was going to try for around 300ah - 400ah.

[Amy@altE]

You are going about it backwards. Figure out how much power you need, then figure out what size battery bank and how much solar. You may only need to use 1 of the solar panels, then you could use a smaller charge controller like the Midnite Kid. Figure out the loads list of what you are trying to power. How many watts and how many hours.

[Rixsta]

Laptop about 14 - 35W (2 hours) Various lights Total aprox 30W (3 hours) Heater 400w (2 hours) could try find a smaller wattage heater, our van is very well insulated so heat should stat in. Charge mobile phones (not sure very small amount) Amplifier 250w Class-A so actualy consumes 250W always (works as a heater too!)

[Rixsta]

Well if anyone has any other ideas, Im about to spend £400 + on a Morningstar MPPT 60A controller, If anyone thinks my idea is silly please let us know

[Mike90250]

Morningstar makes good gear, and the 60A version also has a web interface you can monitor with a browser

[SunEagle]

Well if anyone has any other ideas, Im about to spend £400 + on a Morningstar MPPT 60A controller, If anyone thinks my idea is silly please let us know

Well with 660watts you will need a 60A 12v charge controller and Morningstar is a quality unit. I still did not see what your batteries were rated but based on the panel size you need something around 500 to 600Ah which can safely deliver about ~ 1200wh - 1500wh which should cover your daily loads.

[Rixsta]

Thanks loads for the replies so you think the MPPT 60A Morningstar is reliable?
I don't have batteries yet but will get some soon for now I can handle 400ah cost wise and of corse the figures I gave are worst case power usage so for now I'd keep it low.
I presume the morningstar can monitor the batteries from the LCD or from my laptop.

On eBay there are some high capacity batteries I'll send sone links of them later.
Cheers!

[SunEagle]

The Morningstar TS-MPPT 60A is a quality charge controller and has the ability to monitor the batteries by your computer using an a couple of different communication protocols and RS View software. There is also an optional hardwired remote device called a TriStar that provides system status and alarms.

[Rixsta]

That's great being able to Check the batteries, yes I'll have a laptop to view it all.
Do you know where best to buy the morningstar in England? Best price.. Or if anyone knows of website that sells second hand?

Also one more question

Ok this is important.. I could save a lot by getting the PWM controller by Morningstar is the MPPT overkill for our van? We will be traveling in it and living so..

Just trying to make sure I do the right thing before spending a lot of money.

[SunEagle]

I do not know of a specific place to purchase the morningstar controller so you may have to shop around.

I will say that there is a break-point when a PWM CC is more expensive to use then a MPPT type. That is usually around the 250 watt point. The problem with a PWM CC is that they are designed less efficient than an MPPT. They do not convert the total panel wattage into charging amps and usually require the panels (or groups) to be wired in parallel. That increases the wire size needed because you now add up the panel amps. While a MPPT usually allows more panels to be wired in series which increases the voltage but keeps the amp the same and the wire size smaller.

PWM = Amps in = Amps out
MPPT = Watts in = Watts out.

So it comes down to the total panel wattage being used and the amount of amps required to properly charge the battery system.

[Rixsta]

Cheers
It's all starting to make sense a little.
For a while I was very confused with series vs parallel panel wiring, I'd presumed the power you got from wiring in series was less that parallel due to lower ampage.. But then I realised the watts in both setup are still the same? Otherwise we'd all be wiring in parallel!

Your post is very helpful

My panels in series = about 140 to 145v max in bright English sun. Morningstar MPPT 60A max voltage is 150v.
I never saw my panels go over 47 each would you say it's within safe region? Ok to use