Welcome! Congrats on your Sunny!.
On your 88 Sunline, Yes, Solaris was a series back then and length fit into the series. Travel trailers 25.5 ft to 33.5ft were in the Solaris series.
As to a model number, there was several of them in the series. And length, not sure were the 30' trailer camp from, a prior owner maybe, the 1988 brochure has several in the series at 29'6" which the owner may have rounded up to 30 ft.
You can back into the actual model by looking in the 1988 sales brochure in your FILES section. Find the Solaris models, then line up the floor plan and length that matches your camper. The model number would start with a T and 4 digits.
Knowing the year and model number can help at times when you ask future questions as it tells us the camper have.
To get to the files section, you need to be logged into the forum. At the top of the forum are tabs, look for the word "FILES" click it.
Once into the files section, scroll down to the "Sunline Brochures" section. Go in there and scroll to your year and find a sale brochure for the camper you are looking at and down load a copy.
To your question on where is the power converter, I'm not totally sure, but this can help. Find the shore line power cord outside the camper. This cord plugs into a 120 VAC wall outlet made for the amperage of the camper.
That shore line power cord once it enters the camper, it is wired directly to circuit break box or fuse panel. Follow the cable inside the camper to find that power box. The 120 VAC breakers feeds a few wall outlets, a roof AC unit if you have one, and feeds the 120 VAC to 12 volt DC power converter. There may be other 120 VAC items also. These electrical things are generally down low near the floor, many times inside a bottom cabinet or a special removable wall panel. Find where the shore line cord enters the camper and have a look inside for the items talked about above.
This is all assuming the power system is original or replaced kept in the same original area and was not changed by a prior owner.
Hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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