What should I replace a Sunny Boy 1800 U that is 12 years old?

That is a really small inverter for grid tie.
Who made it? and how old?

Hi chriss and welcome to Solar Panel Talk, um, 1200watts out of a nameplate 1500watt system is probably about right, might no be any need to change that inverter out

smallest I could find in a admittedly 3 minute search is a Fronius but 2000 watt which may be overkill

"Sunny Boy 1800 U" sounds like it would have to be SMA. It appears to be currently available, not sure when it was first marketed.

Folks forget when panels cost $6 a watt that small grid tie systems were built. If you look at back issues of Home Power after their guerilla solar phase, they had many small systems featured. I have a 1000 watt Advanced Energy Grid Tie Inverter that is still putting out power. I have seen several older Grid tied systems equipped with the Sunny Boy 1800 inverters which were built by SMA, at the time they were the most affordable in that range. They also built a 800 watt version. I have also seen several systems over the years with multiple small inverters as dual mppt controllers weren't available.

I am not familiar with the specs on the SB units but be careful on the string configuration to make sure it matches a modern inverter. When my inverter dies I am considering rewiring the array to use microinverters on each panel. Depending on your individual panel voltages, you may be able to put two panels in parallel to match up with microinverter rating. I had spare 8 gauge wire when I installed mine so the panels have individual runs down to a combiner box in my basement so I can do all the wiring in the basement. An alternative I have considered is converting my array into standalone system but will probably investigate microinverters. I expect if I do go that way I will buy one and then see if works before buying an entire set.

By the way, most utilities permit the specific inverter for a grid tie system, if you switch to different inverter, you need to contact them and revise the permit.

How far we have come!

My parents had a PV system installed about 12 years ago, here in San Diego: 12 panels, 2000 watts, SMA Sunny Boy inverter. My folks have passed, and we rent out the house now. The system is still working just fine!

Interestingly, it cost almost exactly the same as the 7.3kW system that we just installed (24 LG305 panels, Solaredge inverter and power optimizers).

They installed it because my mother wanted to do something "green" and she was too old to drive, so an electric or hybrid car was not an option.

Forrest

My first system was built so I could learn the technology, no substitute for hands on. Luckily John Wiles had a great handbook he developed on the design of these systems. I think I got a 10% tax credit and that was it, the financial payback on that system is darn close to "forever" . I have a "Hobbs" meter on its cumulative output, I think its around 8 MW in 12 years. The inverter has one blinking LED and that's it.

It is a wall hung array that acts as a canopy over a large angle bay window. It works real well at shading the window in the summer and I think my average house temp dropped after installation as the angle bay was a big contributor to overheating in the summer. I adjust the angle seasonally so the winter sun still comes in. The only screw up is I have cedar siding and the unistrut touches it in one spot and that's where there is some limited corrosion (not worth fixing). My other two arrays are not much bigger, a 2 KW pole mount and a 2 kw roof mount. I have a 2 MWhr surplus on my bill for this winter and expect it will go up for another month or so when I start using it for heating.

My first system was 8 235 watt canadian solar with enphase M190's
It was $12.00 a watt
I have no idea if it is working as the owner had no internet in the house snd has since passed away.
He was my favorite customer of all time.
He was one of the original navy pilots chosen for NASA. he unfortunately came in # 13. Was a lead progect manager for gemini and merccury programs
Loved hearing his stories

I finally (after over 20 years) have seen this error once on my inverter (following a few-minute voltage excursion to over 135 V) and I haven't been able to find a reference to the details of OP's reset procedure. Does anyone know how it's done on the SWR 1800u or know where to find instructions?

What did you end up getting?