Parallel/Series panel with RSD

I am planning to get 400W panels, and use Tigo DC optimizers to comply with Rapid shutdown device (RSD) requirement and monitor the system.
the panels are
Axitec 400W Solar Panel 108 Cell Bifacial
Short circuit current Isc: 13.79A
Open circuit voltag Uoc: 37.07 V

RSD are required at each individual panel level, but can I use Tigo TS4-A-O (700W) or TAS-A-S (700w),
and parallel/series 2 solar panels into them and still able to comply with RSD requirement?
That way I can cut down the cost of RSD devices, since the only reputable 400W optimizer I see are from SolarEdge P400, and they are not cheap.
There are no shades near the pv array, so I don't need to optimize every panel.

That's how I see it!

400W x 2 > 700W, may not be OK. Except, 400W panel won't produce > 350W except in cool conditions.

An optimizer, I think it would care. But its power handling is likely a curve, depending on voltage conversion.
I see similar limits on Tigo non-optimizing RSD, more restrictive than V and I limits. I doubt it matters for them.

Consider skipping the optimize and monitor function.
Nice to see the data, but I looked for bargain prices on RSD only units.

Hedges said:

Consider skipping the optimize and monitor function.
Nice to see the data, but I looked for bargain prices on RSD only units.

Click to expand...

Tigo TS4-A-F - 700W(rapid shutdown only) is $30 - connect to 2 panels, so $15/panel added cost
Tigo TS4-A-O - 700W(rapid shutdown + optimize + monitor) is $43.53 - connect to 2 panels, so $21.77/panel added cost
The extra cost of $6.77/panel for optimization/monitor is worth it to me since my system is currently designed to be around 20kw.

I've got TS4-A-F and TS4-A-2F which I plan to use for a couple different panels and different installs.

Series connected panels further reduces Voc of string seen by inverter. Some (SMA in particular) rely on that to power keep-alive transmitter.
If yours is separately powered, then not a problem.

If this is the data sheet, looks like you're within max current.
2s panels would be within max voltage named on this data sheet only near nominal temperature, would exceed in cold.
Some models call out 90V absolute max, so I'd feel better using those.

RSD rules of course say 80V max between any 2 wires in the array.
Maybe that is under nominal conditions?
But then, with each RSD putting out 0.6V, depending on whether both ends of PV string are isolated (or if it is shorted, which I don't think?) a string of 12 panels using 6 RSD might have 5 x 0.6V = 3V additional. Not much, might technically violate.

Some people on the forum have said 2s into one RSD is OK for the lower cell count panels.

Your other issue is you are pushing watts. For an optimizer, it has to process that power.
See if you can find one good for higher wattage since you are close to over the spec.

The TS4-A-2F is your absolute best value for money as it will handle two panels but there is no optimization whatsoever, it's just an on-off switch.
Many inverters have the keep alive signal module built into them to drive the Tigo TS4-A-2F/TS4-A-F.
I would not over run those other modules by that much, way too much and I have seen cloud edging and sunspot activity push my panels even higher than their rated output quite easily.

I actually want to put 4 panels on TS4-A-2F.

In that case 12s panels is only 3 RSD, about 1.8V out.
For that application I would be using Tigo's RSD transmitter.
(Or a "12V" panel into unused inverter MPPT input?)

Apologies if I misunderstand the discussion. fwiw - Considered similar equipment last year and decided to KISS. Having a separate RSD transmitter with only a 5 year warranty may not be as advantageous as an inverter with a 10 to 25 year warranty that xmits the RSD signal. And having the same inverter and RSD manufacturer ensures no compatibility issues. And, if something does go wrong their is no finger pointing between manufacturers. Is overall efficiency with several optimizers better than RSD's with a quality inverter from the same manufacturer.

Failure rate of panels is .05%. Is it worth monitoring that. Good installation practices are far more important.