Thanks to advice received from other "Funsters" we have recently upgraded the solar system on our van. Considering how dull the weather has been so far this summer we have been impressed by how much more efficient the system is now.
We thought other might benefit from an account of how we did it.
Firstly I replaced the dealer installed regulator with one recommended by @Techno, MPP SOLAR PCM-3012. The old regulator never brought the batteries above 13.6v on bulk charge and 13.1v floating, the new one to 14.3v and 13.4v Also I upgraded the cabling to the battery to 4mm2. The final addition inside the van was to instal a Sterling "Auxiliary Battery-Battery Charger/Maintainer" to keep the engine battery charged. This I can't remember who recommended.
Next, on the roof, I added a 100 watt panel to augment the existing 2x 85 watt panels that the dealer had instaled. I added a blocking diode to the new panel and a diode into the feed from the original panels. 4mm2 cable was used to the regulator from the new panel and from the diode added to the orginal panels. The dealer had glued and screwed the 85 watt panels to the roof (using zinc coated steel wood screws that had rusted, I replaced them with S/S self tapping screws and plenty of sealant). I decided to leave the original panels well alone as their output voltages and currents were within spec.
The upshot being that today, even in the rain, we were often getting up to 2.5 amps charging current. Thanks again to all "Funster" who gave advice.
We thought other might benefit from an account of how we did it.
Firstly I replaced the dealer installed regulator with one recommended by @Techno, MPP SOLAR PCM-3012. The old regulator never brought the batteries above 13.6v on bulk charge and 13.1v floating, the new one to 14.3v and 13.4v Also I upgraded the cabling to the battery to 4mm2. The final addition inside the van was to instal a Sterling "Auxiliary Battery-Battery Charger/Maintainer" to keep the engine battery charged. This I can't remember who recommended.
Next, on the roof, I added a 100 watt panel to augment the existing 2x 85 watt panels that the dealer had instaled. I added a blocking diode to the new panel and a diode into the feed from the original panels. 4mm2 cable was used to the regulator from the new panel and from the diode added to the orginal panels. The dealer had glued and screwed the 85 watt panels to the roof (using zinc coated steel wood screws that had rusted, I replaced them with S/S self tapping screws and plenty of sealant). I decided to leave the original panels well alone as their output voltages and currents were within spec.
The upshot being that today, even in the rain, we were often getting up to 2.5 amps charging current. Thanks again to all "Funster" who gave advice.