Thread: MPPT solar controller

Originally Posted by drivesafe

Hi Graham and as posted above, the 80w panel is just too small.

On a good day you will only average around 2 amps per hour over 8 hours and this requires your Def to be parked in the sun all the time. So way too little power for what you need.

As to the Ctek, not sure why you needed that in the first place.

The MPPT in the Ctek is not that good and your alternator can supply far better charge voltages that the Ctek does, particularly if you are planning to fit more that one battery.

The more battery capacity you need to charge, the longer a DC/DC charger will take, whereas your alternator will automatically adjust it’s output to cater for more battery capacity needed to be charged.

So you end up RECHARGING batteries much faster off an alternator, which means you don’t need to drive as long to get your batteries charged.

If you are going to be with your Def all the time, then also as suggested above, a portable folding panel set up would be more advantageous and would allow you to park the Def in the shade.

I do have a second battery or aux as I call it. The idea with the Ctech was its permanently mounted and automatic, it decides where it charges the the aux battery from i.e. solar or alternator via the main battery. As already discussed the solar controller performance is poor.
I also wanted to mount the solar panel on the truck as I saw someone's portable folding solar panels backed over at their campsite and my system is operating all the time, nothing to set up. I'll just have to get another panel and a better performing controller.

I have a 120w panel mounted on the roof with a projecta solar regulater connected to my aux battery, I have a 40l arb fridge in the back which doesnt get turned off ( unless it gets cleaned ). Just recently I have installed the SC-80 from Trxide and I am very happy with the unit.

The module is mounted to a gullwing? Mounted on a near vertical surface like that it won't produce much at all. Yes, solar modules have to be "in the sun" to work, but they have to be facing the sun to output anything like rated power.

Current out of a photovoltaic module is directly proportional to incident sunlight. An easy way to work out how much sunlight you're getting is to imagine how large the shadow a module at that orientation is casting onto flat ground. Standing up like you have it, the shadow would be tiny. Lay it flat, the shadow would be much larger and hence the current output much larger as well.

The upshot of that is: before you buy anything, trying mounting the module on the bonnet. No MPPT is going to help you with the solar module mounted there.

I have one ofthese in the caravan with the optional remote display panel and I love it.
It's connected to a 120w folding panel.
Because it's proper MPPT, I have re-wired the panels in series, this way the array runs at 24v (it's actually up near 37-40) so the 15m run of 2.5mm sq outdoor lighting cable loses very little power. Just last week in Bright I was getting 7.5 amps at 14.1v in real life.

If the loads are also wired through it, it will directly power the load from the sun, whilst redirecting excess power to the battery, and the readout will show daily usage/charge etc.
Have a look at this video if you are interested:
[ame="http://www.youtube.com/watch?v=DrG3ilmxrFU"]here[/ame]

Cheers,
Fraser

Originally Posted by Dervish

The module is mounted to a gullwing? Mounted on a near vertical surface like that it won't produce much at all. Yes, solar modules have to be "in the sun" to work, but they have to be facing the sun to output anything like rated power.

Current out of a photovoltaic module is directly proportional to incident sunlight. An easy way to work out how much sunlight you're getting is to imagine how large the shadow a module at that orientation is casting onto flat ground. Standing up like you have it, the shadow would be tiny. Lay it flat, the shadow would be much larger and hence the current output much larger as well.

The upshot of that is: before you buy anything, trying mounting the module on the bonnet. No MPPT is going to help you with the solar module mounted there.

I mounted the panel via a piano hinge. When I get to the campsite I swing it up to a position facing the sun. Opening the gull wing door has the same effect. Had to do it this way as I carry a tinny on the roof.