Club 80-90 Forums

I measured my old panel in the same way but found the reading to about 30% lower than when I connected it to a controller and measured the current going to a fairly flat battry.

Typically the only sunny day we have had for a while and I'm at work, the next few days are going to be cloudy!

Why the 20A controller guys and not the 10A?

willpom wrote:Why the 20A controller guys and not the 10A?

Its a double controller so has two outputs for two batteries.

CJH wrote: The photo in the eBay listing* shows the connectors inside the junction box, but that photo suggests that the surface of the panel was damaged around the junction box on that particular unit - was that caused by opening the junction box perhaps?

Specsavers appt. needed - that is just the protective t r a n s i t film that has been removed to allow the affixing of the box!

Oldiebut goodie wrote: Specsavers appt. needed - that is just the protective t r a n s i t film that has been removed to allow the affixing of the box!

Hehe - I did wonder about that. One of the suppliers I emailed has confirmed that the junction box cover does come off, and that it's OK to use 13A twin core domestic flex. So a bit of white flex should look slightly less obtrusive than the black pigtails I reckon.

keith wrote:Its a double controller so has two outputs for two batteries.

Why not a 10A double charger as the solar in is a max of 5.56ish
http://www.ebay.co.uk/itm/271344399110? ... EBIDX%3AIT

willpom wrote:

keith wrote:Its a double controller so has two outputs for two batteries.

Why not a 10A double charger as the solar in is a max of 5.56ish
http://www.ebay.co.uk/itm/271344399110? ... EBIDX%3AIT

I dont think i could find the 10 amp as cheap as the 20 amp from the uk last week.

Im sure the 10 amp would work just fine though as its double the best output you could expect from 100 w panel

keith wrote:I dont think i could find the 10 amp as cheap as the 20 amp from the uk last week.

Ahha, I see.

In the wiki it talks about putting in series add volts, parallel add Ah. Is this the same for panels? So 2 100W in parallel would give 11.2A under optimum with same voltage, so a 20A charger controller would be best?
https://club8090.co.uk/wiki/Ca ... ng_systems

And another question. The charger/controller (20A or 10A) has a negative return for each battery. Would a wire have to be run to each, or could I run both to the chassis as both leisure and starter do? More of a wiring issue this, there is enough space in the wire 'conduit' from the starter to the leisure location for one wire, two and I'd have to think about more holes, grommets etc.

willpom wrote:

keith wrote:Its a double controller so has two outputs for two batteries.

Why not a 10A double charger as the solar in is a max of 5.56ish
http://www.ebay.co.uk/itm/271344399110? ... EBIDX%3AIT

I have a 20a controller. I not sure if I'm correct in thinking but at points I will be drawing upto 15A through the load side of the controller.

Another good point to having a higher amperage controller is that if you want additional panels to your system, you won't have to buy different controller to meet that increased amperage.

ninja.turtle007 wrote:I not sure if I'm correct in thinking but at points I will be drawing upto 15A through the load side of the controller.

Not sure if that is right Tom, you shouldn't draw any load through the charger/controller it should be protected by that. If I'm right in my understanding there will be diodes in the charger controller that only allow current to flow to the batteries, not the other way around. Otherwise a solar panel at night actually becomes a drain as electrons drop back to a different state.

Timwhy wrote:Another good point to having a higher amperage controller is that if you want additional panels to your system, you won't have to buy different controller to meet that increased amperage.

Could be a few extra quid well spent to future proof then!

willpom wrote:

ninja.turtle007 wrote:I not sure if I'm correct in thinking but at points I will be drawing upto 15A through the load side of the controller.

Not sure if that is right Tom, you shouldn't draw any load through the charger/controller it should be protected by that. If I'm right in my understanding there will be diodes in the charger controller that only allow current to flow to the batteries, not the other way around. Otherwise a solar panel at night actually becomes a drain as electrons drop back to a different state.

Timwhy wrote:Another good point to having a higher amperage controller is that if you want additional panels to your system, you won't have to buy different controller to meet that increased amperage.

Could be a few extra quid well spent to future proof then!

Most controllers have 3 sets of terminals, panel, charge to battery and a load pair which are connected to the internal lvd circuit so that the load doesn't flatten the battery. The controller is built for drawing the load through hence 10A/20A/30A etc. rating which applies to the load just as much as the output of your panels.

Glad I've raised some interest in this topic - i am learning a lot.

Thought this page was worth a quick look for those doing this mod - some sensible safety precautions on an install and reminder of what just a few amps can do.....

http://www.solarjourneyusa.com/learn-build-array.php

willpom wrote:And another question. The charger/controller (20A or 10A) has a negative return for each battery. Would a wire have to be run to each, or could I run both to the chassis as both leisure and starter do? More of a wiring issue this, there is enough space in the wire 'conduit' from the starter to the leisure location for one wire, two and I'd have to think about more holes, grommets etc.

Cant answer this directly as I had dual core wire so it was easier to pass both wires together and hook it up to the -ve terminal. However to measure the volts I cant see that it would make any difference if you put it to another earth - both that and the -ve terminal should be at 0 potential and therefore the volts read should be the same. I dont think this is the same when it comes to the charging of the battery by the solar panel - you have to complete the circuit for the amps to flow through the battery and round the circuit (I am prepared to be corrected on this though).

Still no further on with my install although I have bought the Sikaflex EBT from Screwfix for the fixings to the roof when the weather means I want to get out there and do it!

Mines done, I used a controller that I already had whilst I wait for a 20A controller and power meter to arrive.

I just need some sun!