[Edit: The following files are no longer supported or recommended, except if you need to parallel 4 kW and 5 kW machines. Please see the Firmware section of the index post to find the latest version for your model. But the following reflashing instructions are the only ones available, and are still valid for the newer versions, although we no longer recommend updating the SCC firmware.]
dsp_LF1_72.70b.zip (For lithium ferrous phosphate (LFP) only (16s))
dsp_Pb1_72.70b.zip (For other lithium ion chemistries (14s), and lead-acid (24s))
SCCMPPTReflash_V4.10.zip (if needed; 1.8 MB)
NOTE: the above LFP and Pb patched firmware is for the PIP-4048MS / Axpert MKS 5kVA; it is probably not suitable for use with a PIP-4048HS, Axpert KS (note lack of "M"), or other non-MPPT based inverter. It will also not work on 24 V or 12 V inverter models. While it is possible that the patched firmware might work in a non-MPPT inverter with only minor problems (such as allowing 60 A of solar charge current when the hardware is only capable of 50 A), it is also possible that other hardware incompatibilities could cause the inverter to blow up. Such operation has never been tested and is highly discouraged.
NOTE: the above V4.10 SCC firmware is for the SCC inside a PIP-4048MS / Axpert MKS 5kVA; it is not suitable for use with a PCM60x or other stand alone solar controller. The PCM60x and the SCC seem to have essentially the same hardware, but the PCM60x makes its own decisions about voltage and current, and drives its own display, while the SCC has no display of its own, and relies on messages from the Axpert's DSP (Digital Signal Processor) to tell it what to do.

You will need a Windows computer and a USB to D9 serial adapter, or a very old computer with a real serial port. You can't use the USB port of the inverter if it has one; that's only for monitoring programs. (Exception: some lower power models only have a USB port, in those cases the Windows reflash tool is different and is able to talk to the USB port. For those models, the USB to serial adapter is not used, and a standard USB cord, as you would use for a printer, is used instead.) Use the serial to RJ45 cable that came with your inverter-charger. (Lost it? Pinout here.) Some serial adapters (or possibly the combination of serial adapter and Windows version) seem to be more suitable than others; see earlier posts on this. The known-good USB to serial adapters use a PL2303 chip; see this post.
If, when you plug in your serial adapter, you get a notification similar to "a device is undergoing additional setup", wait until it says something like "update complete".
Power up your inverter charger by connecting the battery, which should not be nearly empty. Turn on the inverter switch. Make sure that your computer has power that won't go off during the reflash process. Disconnect all loads, and disconnect solar panels unless you are updating the SCC firmware.
Download and unzip the appropriate zip file above. Use the Windows File Manager "Extract All..." context menu item (right click menu) and follow the prompts to extract into a new folder. Make sure you are not running any software that could be using the serial port, in particular, exit the WatchPower application. Don't just close the application; use the right mouse button on the WatchPower system tray icon, usually at the bottom right of Windows:
The file name the reflash tool looks for is fixed, it's always "dsp.hex" in the same folder as the reflash tool. In the zip file, dsp.hex is already a copy of the patched firmware.
Finally, double click on the ReflashTool_Xseries.exe icon. If you get a box with something like "The app you're trying to install isn't a verified app from the Store", click Install anyway. This should bring up the small reflash application. If necessary, change the serial port selection to the one that connects to your inverter.
Click on the Update button, and answer Yes to "Are you sure". Nothing will appear to happen for 10-20 seconds, so don't panic. Eventually, new text should start appearing in the box under the progress bar, saying that erasing has been successful and so on. It will take some 8 minutes to complete the flash programming. At the end, just click OK and exit the reflash application.
If you get an error to do with the serial port (e.g. invalid serial port, or the serial port doesn't appear in the drop down list), it's probably because you have something running that is keeping the serial port in use. Double check that you have exited WatchPower and any terminal emulation programs like TeraTerm. You may need to change the com port used by the USB to serial adapter to be named COM1 through COM9 for the reflash tool to see it (Device Manager, Ports, Properties, Advanced; step by step guide here if you need it). Merely choosing another USB socket on your computer might work. On my laptop, the two most convenient USB ports come up as COM10 (not usable) and COM6 (usable). After changing ports, restart the reflash tool; it doesn't refresh its list of available COM ports.
The standard instructions say you should revert all the settings to standard, then change them to suit your needs. As long as you had been running a recent firmware (52.30 or later), this should not be necessary. But if you were running an earlier firmware, or if the settings seem strange after the update, use WatchPower to reset to default settings, then change them to suit your needs.
The instructions say to turn off the inverter after the firmware update. This doesn't seem to be necessary.
If something goes wrong, see the If you think your inverter is bricked post.
Using Watchpower
WatchPower comes for free and allows basic interaction with the inverter(s). However, many find that it does not meet all their needs. In this case, consider some of the many other monitoring programs available. A few of them are referenced from the index at the start of this thread.
WatchPower is not aware of the changes to the range of the battery low cutoff voltage and the back to utility voltage parameters. You will not be able to change these values with WatchPower outside their original range. Instead, you can use the LCD buttons, or any software that changes these settings via the PSDV or PBCV commands.
SCC updating
[Edit: This is no longer required or recommended, with DSP patched firmware version 72.70c or later.]
It's not essential to update to the latest SCC firmware when updating the DSP firmware, especially if you don't think you'll need more than 60 A of maximum charge current.
There are two reasons why updating the SCC firmware is a little more difficult than updating the DSP firmware.
Firstly, the updating process uses a completely different updating program, and for whatever reason, they insist that the USB to serial adapter has to be on COM1. To do this, run Device Manager, under Ports (COM & LPT) locate your USB to serial adapter, right click to bring up the context menu, and select Properties. Choose the Port Settings tab. Click Advanced... and in the COM Port Number drop down box at the bottom of the dialog select COM1. Restart the computer for this to take effect.
Secondly, there is a .OCX driver that needs to be registered. There are instructions for this in a PDF file with the other upload files. You need to run a command prompt as administrator and enter a command to regsvr32.exe with the name of the .OCX file as its only argument. You can use the tab key to help fill in parts of the path (path completion? A bit like command completion). It's not too hard, and you only need to do this once. If you get an assert failure when you attempt to flash the SCC firmware, it's possible that this OCX registration hasn't happened or didn't succeed (perhaps an incorrect path to the .OCX file was given).
Remember also that the SCC is only powered up from the PV inputs. So make sure that you have PV input. An easy check is to attempt to view the SCC firmware's version number. If you can see that, the SCC is powered up and talking to the DSP.
[ Edit: Added notes to disconnect all loads, and disconnect solar panels unless updating SCC. Also, battery should not be nearly empty. ]
[ Edit: Added sentence (was paragraph briefly) about additional setup. ]
[ Edit: Added comments re app store and trying different USB ports. ]
[ Edit: Removed comment about no folder inside the zip file. ]
[ Edit: "Registration failure hasn't happened" -> "registration hasn't happened". ]
[ Edit: "USB port" -> "USB socket on your computer". ]
[ Edit: Added link to step-by-step guide for renumbering a COM port. ]