wiring solar panels

[Cloudinspector]

I'm about to fit 2x100w solar panels and mppt controller to a battery bank of 4 domestic plus starter battery. Am i correct in thinking that i need to wire the panels in parallel and how do i connect to the bank? positive and negative to one battery or pos at one end of the bank and neg at the other?

 

Ta

Edited May 8, 2013 by Cloudinspector

[pelicanafloat]

My 2 panels are connected together via dual mc4 connectors, the positives combined via 4mm cables into the connector and then I ran a 6mm cable to the controller. Ditto, the negative... I Used 6mm cable to reduce power losses.

 

I connected the controller to the batteries via a DC link box (in my case, a victron fused link box) incorporating a 60a Mega fuse.

 

So, basically you need to just combine the positives and run a positive cable to the controller, and do the same for the negative, both cables wired into the controller. Then run a fused + cable to a handy and effective battery live terminal; and a negative cable to a decent and effective negative battery terminal; and just make sure all your battery connections are tight and clean.

 

The controller will ascertain what voltage your batteries are delivering. All you have to worry about is getting decent watertight connectors and making sure your cables are big enough, and the + fused.....

 

That's my input :-)

[Justme]

Not enough info to make a recommendation.

 

Need the max OCV voltage of each panel & the max working voltage of your MPPT controller.

 

You might need to do them in series or parallel depending on those points.

 

 

Re connection to battery bank. ALL connections should be to the same positive & negative points.

[trackman]

Justme is correct, either series or parallel panel wiring may be used depending on lots of variables (voltage capacity of controller being just one).

 

There are loads of threads on the forum explaining the details, try searching for and reading these.

[smileypete]

Would also help to know rough distance between panels and MPPT, and distance between MPPT and batts, as well as details of MPPT and panels.

 

4mm² is the minimum size for pre-made solar panel cables, if on a tight budget then 2mm² or 2.5mm² should do fine for 200W of solar.

 

6mm² cable would be the minimum size between MPPT and batts, with 200W panels, but it depends greatly on distance, probably a bigger size could be worthwhile.

 

Usually 2 panels would be connected in series 'daisy chained' for MPPT but depends on panel max voltage and MPPT max voltage.

 

Don't forget a fuse near in the +ve near the batt, 20A should do.

 

cheers, Pete.

~smpt~

Edited May 8, 2013 by smileypete

[Cloudinspector]

More info,

Short circuit current 6.01 amps

Open circuit voltage 21.5 volts

Optimum operating current 5.52 amps

Optimum operating voltage 17.78 volts

Max power 100w

 

Tracer 20amp mppt controller

 

The panels will be fitted end to end so the longest distance to mppt will be about 3 metres.

Distance from mppt to battery bank is about 2 metres

[Paul C]

More info,

Short circuit current 6.01 amps

Open circuit voltage 21.5 volts

Optimum operating current 5.52 amps

Optimum operating voltage 17.78 volts

Max power 100w

 

Tracer 20amp mppt controller

 

The panels will be fitted end to end so the longest distance to mppt will be about 3 metres.

Distance from mppt to battery bank is about 2 metres

#

A quick Google shows that the max input voltage is 150V, so you'd be fine in series (and parallel if you really wanted to). I'd do it in series, for (lesser) voltage drop reasons.

[smileypete]

More info,

Short circuit current 6.01 amps

Open circuit voltage 21.5 volts

Optimum operating current 5.52 amps

Optimum operating voltage 17.78 volts

Max power 100w

 

Tracer 20amp mppt controller

 

The panels will be fitted end to end so the longest distance to mppt will be about 3 metres.

Distance from mppt to battery bank is about 2 metres

 

OK, sounds good, everything in post #5 still holds in that case, but it wouldn't hurt to use 10mm² between MPPT and batts if it doesn't work out that much dearer.

 

I'd probably try and put the two panels with the junction boxes 'back to back' then join them in series and get extra cable to cover the distance to MPPT.

 

If there's say 2m needed to reach MPPT from panels you could buy a single 5m extension ready fitted with plug and socket on each end and cut it in half or thereabouts to suit.

 

For going through steel bulkheads from outdoors a cheap way of doing it is to use M16 or M12 cable glands, they need a 16mm or 12mm hole and fit a range of cable sizes.

 

cheers, Pete.

~smpt~