According to the Rogue controller manual the PV amp limit is 25 amps at 12 volts and 12.5 amps at 24 volts.
That's incorrect. The Rogue is rated for 30 amp output with either a 12v or 24v nominal system. If you're installing to NEC regulations, then you have to observe the rule for derating, which arbitrarily limits PV output to less than the capacity of the controller. That's true for any controller that you want to install to be code compliant.
Also be aware that the Blue Sky 3024 will limit current to 30A unless you're using both a 12v battery and PV with a Voc of less than 30v. A 24v/12v or 24v/24v installation will be limited to 30A.
The devil is in the details. Rogue in their manual states that it is best to wire the panels in series but also states that a "24-volt nominal array, which may produce more than 45 volts open-circuit on a cold sunny day, is the maximum recommended array configuration to use with this controller". The MPT-3024 has a limit as to the input voltage. So this controller can handle 4 or more panels wired in parallel but only 2 panels if they are wired in series.
Something to consider if choosing between the Rogue and the Blue Sky controllers is that the Blue Sky has reverse battery protection while the Rogue does not and in their manual they state "connecting a battery backward across the BAT or PV terminals will cause immediate and irreversible damage to the controller, which is not covered under warranty".
As for "derating" and "arbitrarily limits" the NEC code actually states that as the PV input can vary with weather conditions a controller needs to be able to handle 125% of the rated PV input value. This reg applies to the ratings of all manufacturers' controllers and not just those from Rogue. With the Blue Sky 3024 the "current rating and current limit are 40A when charging a 12v battery from nominal 12V PV modules. If PV Voc ever exceeds 30V (>12V nominal PV modules) current rating and current limit become 30A".
The Rogue controller is also designed for use with 6ga wire internally and they recommend using separate additional junction boxes to connect 4ga wire from the batteries to 6ga wires to the controller. With the Blue Sky 3024 box I can run 4ga wire straight to the internal bus and have mechanical strain relief with the controller boxes knockouts.
One reason for not going with the Blue Sky 2512 or Morningstar controllers was the need to have multiple junction boxes around the controller. Not a big deal for a typical PV setup for a house but hardly ideal when installing the controller in a small camper with very limited space and even more limited access.
So does every other charge controller. The Blue Sky 3024's is 57v. the Rogue's is 60v.
Something to consider if choosing between the Rogue and the Blue Sky controllers is that the Blue Sky has reverse battery protection while the Rogue does not...
Adding reverse battery protection usually means lower efficiency and/or mechanical components (relay) that can wear out. Mistakes do happen, but it's fairly easy to make sure you have the polarity of your wires correct before connecting them to the controller.
As for "derating" and "arbitrarily limits" the NEC code actually states that as the PV input can vary with weather conditions a controller needs to be able to handle 125% of the rated PV input value.
Right. So basically you want to leave 25% headroom to accomodate that potential overage.
The Rogue controller is also designed for use with 6ga wire internally and they recommend using separate additional junction boxes to connect 4ga wire from the batteries to 6ga wires to the controller.
The terminal block on the Rogue takes up to 4ga wire. However, it's suggested to use no larger than 6ga within the controller simply because larger wire is more difficult to bend and secure.
I have 2 AMsolar 100w panels on my roof connected in series. ( great customer service ). I have them connected via the Lance wiring ( I think it is 10g, check the owner's manual) to a BZ high voltage MPPT controller. The panels are generally producing around 40v, and the controller is rated for 100v. By mounting the controller near the batteries the need for high amperage wiring is minimized, so I have the controller mounted 18" from the battery bank. The system has been in use for 2 years now and is working flawlessly. PM me if you like, I am in your area if you want to see how I did the install.
PS I have received great customer service from Lance every time io have emailed them with a question or a problem.
I would like very much to see your installation and see what you did and hear what you might do differently if you had it do do over again.
When I mentioned RV manufacturers not making their vehicles easy to add solar I was referring to undersized wires going to battery banks, lack of space to add another one or two or more batteries, no wiring in the roof space or walls to use for running wires. Lance puts up a non-standard roof connector with 12ga wiring running to a location under the kitchen sink and from there to a tiny opening under the bath sink with very little access space and no place to readily mount a controller or fuses or anything else.
I am used to boats where by design all the wiring is readily accessible (except the wiring in the mast) as is battery storage areas and all wiring runs are easy to follow and the panels when pulled out provide ready access to everything connected in to them. With the Lance camper I would need to tear apart cabinetry to get access and although the generator compartment has 6ga wire running to the space by the battery compartment it is to short to use without splicing to connect to a battery bank instead.
The RV industry puts on ladders and roof racks and AC units and powered TV antennas and satellite dishes so expecting them to pre-wire and provide a way to run mounting rails to install solar panels is not that far fetched. If they were smart they would offer it as an option and let people elect to have factory installed 200 watt, 400 watt, or 800 watt systems that were done properly with all the necessary wire and connectors and mounted to avoid hitting wiring or ripping out from the roof. Cable runs could be 100% internal instead of run along the roof and drowned in sealant.
I am currently looking for UV resistant 8ga duplex wiring with black and white wires (to meet the NEC code and minimize problems) and even there I am finding I need to buy a 100' spool to get the 12-15 feet I will need to mount the panels on my roof and wire them into a C-box.
I really don't know what I might hit when I screw the panel mounts and cable clips to the roof so I am going to be guessing and hoping for the best. The manufacturer would not need to guess and can buy the items needed for half of what it is costing me or anyone else.
My first car did not have a radio or a heater as they were both options. Now these are considered essential and it would be impossible to find a car without them. Same happened with generators in RV's and it time for the same to happen with solar. Lance has provided a solar capability but it is pretty lame by any standard. And this seems to be true for million dollar motorhomes and expensive 5th wheel trailers as well so it is an industry wide deficiency on the part of the people running the companies.