Speaking of PV optocouplers, here's an amp that can swing 600 volts p-p (or more, if you want it) using maybe $10 worth of parts.
The R12...C4 thing corrects for a bit of transient overshoot. It might not be necessary if I get energetic and compensate the main loop a little more scientifically.
Version 4 SHEET 1 880 796 WIRE -304 -272 -368 -272 WIRE -272 -272 -304 -272 WIRE -32 -272 -112 -272 WIRE 0 -272 -32 -272 WIRE 304 -272 224 -272 WIRE 416 -272 304 -272 WIRE 416 -240 416 -272 WIRE -368 -224 -368 -272 WIRE -112 -224 -112 -272 WIRE -1520 -144 -1584 -144 WIRE -1440 -144 -1520 -144 WIRE -1248 -144 -1360 -144 WIRE -1120 -144 -1248 -144 WIRE -1024 -144 -1120 -144 WIRE -864 -144 -960 -144 WIRE -688 -144 -784 -144 WIRE -608 -144 -688 -144 WIRE -560 -144 -608 -144 WIRE 224 -128 224 -272 WIRE -368 -112 -368 -144 WIRE -112 -112 -112 -144 WIRE 416 -112 416 -160 WIRE -1248 -48 -1248 -144 WIRE -112 -48 -368 -48 WIRE 80 -48 -112 -48 WIRE 176 -48 80 -48 WIRE -1024 -16 -1040 -16 WIRE -992 -16 -1024 -16 WIRE -928 -16 -992 -16 WIRE -816 -16 -848 -16 WIRE -784 -16 -816 -16 WIRE -112 0 -112 -48 WIRE -992 32 -992 -16 WIRE -368 48 -368 -48 WIRE 80 48 80 -48 WIRE -448 64 -464 64 WIRE -416 64 -448 64 WIRE 224 64 224 -32 WIRE -1248 80 -1248 32 WIRE -112 96 -112 64 WIRE -448 112 -464 112 WIRE -416 112 -448 112 WIRE -992 128 -992 96 WIRE -896 128 -992 128 WIRE -784 128 -896 128 WIRE -992 160 -992 128 WIRE -1120 176 -1120 -144 WIRE -1024 176 -1120 176 WIRE -688 192 -688 -144 WIRE -688 192 -960 192 WIRE -1536 208 -1616 208 WIRE -1392 208 -1456 208 WIRE -1184 208 -1392 208 WIRE -1024 208 -1184 208 WIRE -368 224 -368 128 WIRE -112 224 -112 176 WIRE -112 224 -368 224 WIRE 80 224 80 128 WIRE 80 224 -112 224 WIRE 224 224 224 144 WIRE 224 224 80 224 WIRE 352 224 224 224 WIRE 480 224 352 224 WIRE 528 224 480 224 WIRE 544 224 528 224 WIRE -896 240 -896 128 WIRE -784 240 -784 128 WIRE -688 240 -688 192 WIRE -1392 272 -1392 208 WIRE 352 272 352 224 WIRE 480 272 480 224 WIRE 224 304 224 224 WIRE -1616 320 -1616 208 WIRE -1248 320 -1248 272 WIRE -992 352 -992 224 WIRE -896 352 -896 304 WIRE -896 352 -992 352 WIRE -784 352 -784 320 WIRE -784 352 -896 352 WIRE -992 368 -992 352 WIRE -688 384 -688 320 WIRE -112 384 -368 384 WIRE 80 384 -112 384 WIRE 176 384 80 384 WIRE 352 384 352 336 WIRE 480 384 480 352 WIRE -1392 400 -1392 352 WIRE -112 432 -112 384 WIRE 432 448 352 448 WIRE -368 480 -368 384 WIRE 80 480 80 384 WIRE 352 480 352 448 WIRE -1024 496 -1040 496 WIRE -992 496 -992 432 WIRE -992 496 -1024 496 WIRE -928 496 -992 496 WIRE -816 496 -848 496 WIRE -784 496 -816 496 WIRE -448 496 -464 496 WIRE -416 496 -448 496 WIRE 224 496 224 400 WIRE 432 496 432 448 WIRE -1616 512 -1616 400 WIRE -1392 512 -1392 464 WIRE -1248 512 -1248 400 WIRE -112 528 -112 496 WIRE -448 544 -464 544 WIRE -416 544 -448 544 WIRE -368 656 -368 560 WIRE -112 656 -112 608 WIRE -112 656 -368 656 WIRE 80 656 80 560 WIRE 80 656 -112 656 WIRE 224 656 224 576 WIRE 224 656 80 656 WIRE 320 656 224 656 WIRE 432 656 432 576 WIRE 432 656 320 656 FLAG 528 224 OUT FLAG 416 -112 0 FLAG 352 384 0 FLAG 304 -272 +350 FLAG -1520 -144 OUT FLAG 352 480 0 FLAG 320 656 -350 FLAG -1248 512 0 FLAG -368 -112 0 FLAG -112 -112 0 FLAG -304 -272 +5 FLAG -32 -272 -5 FLAG 480 384 0 FLAG -688 384 0 FLAG -1024 -16 A FLAG -1024 496 B FLAG -448 496 B FLAG -448 112 A FLAG -1248 80 0 FLAG -1184 208 IN FLAG -1616 512 0 FLAG -1392 512 0 FLAG -608 -144 AMP FLAG -816 -16 +5 FLAG -816 496 -5 FLAG -448 64 +5 FLAG -448 544 -5 SYMBOL nmos 176 -128 R0 WINDOW 0 88 46 Left 2 WINDOW 3 -125 -61 Left 2 SYMATTR InstName M1 SYMATTR Value STN3N45K3 SYMBOL nmos 176 304 R0 WINDOW 0 72 42 Left 2 WINDOW 3 -174 -6 Left 2 SYMATTR InstName M2 SYMATTR Value STN3N45K3 SYMBOL res 208 48 R0 WINDOW 0 66 35 Left 2 WINDOW 3 61 70 Left 2 SYMATTR InstName R2 SYMATTR Value 500 SYMBOL voltage 416 -256 R0 WINDOW 0 66 41 Left 2 WINDOW 3 59 75 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 350 SYMBOL cap 336 272 R0 WINDOW 0 54 17 Left 2 WINDOW 3 55 49 Left 2 SYMATTR InstName CL SYMATTR Value 22n SYMBOL res 64 32 R0 WINDOW 0 -60 50 Left 2 WINDOW 3 -75 85 Left 2 SYMATTR InstName R3 SYMATTR Value 500K SYMBOL g -368 32 R0 WINDOW 0 31 113 Left 2 WINDOW 3 32 143 Left 2 SYMATTR InstName G1 SYMATTR Value 2m SYMBOL diode -128 0 R0 WINDOW 0 51 24 Left 2 WINDOW 3 56 54 Left 2 SYMATTR InstName D1 SYMBOL voltage -112 80 R0 WINDOW 0 -85 44 Left 2 WINDOW 3 -77 75 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V5 SYMATTR Value 8 SYMBOL res 208 480 R0 WINDOW 0 61 38 Left 2 WINDOW 3 57 75 Left 2 SYMATTR InstName R1 SYMATTR Value 500 SYMBOL res -1344 -160 R90 WINDOW 0 71 56 VBottom 2 WINDOW 3 78 55 VTop 2 SYMATTR InstName R6 SYMATTR Value 4.99Meg SYMBOL res -1232 48 R180 WINDOW 0 81 58 Left 2 WINDOW 3 69 23 Left 2 SYMATTR InstName R8 SYMATTR Value 100K SYMBOL res 64 464 R0 WINDOW 0 -60 50 Left 2 WINDOW 3 -75 85 Left 2 SYMATTR InstName R9 SYMATTR Value 500K SYMBOL g -368 464 R0 WINDOW 0 31 113 Left 2 WINDOW 3 32 143 Left 2 SYMATTR InstName G2 SYMATTR Value 2m SYMBOL diode -128 432 R0 WINDOW 0 51 24 Left 2 WINDOW 3 56 54 Left 2 SYMATTR InstName D4 SYMBOL voltage -112 512 R0 WINDOW 0 -85 44 Left 2 WINDOW 3 -77 75 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V2 SYMATTR Value 8 SYMBOL voltage 432 480 R0 WINDOW 0 68 46 Left 2 WINDOW 3 62 83 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V3 SYMATTR Value 350 SYMBOL voltage -1248 304 R0 WINDOW 0 -51 177 Left 2 WINDOW 3 -67 265 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V4 SYMATTR Value SINE(0 5 100 0 0 0) SYMBOL voltage -368 -240 R0 WINDOW 0 66 41 Left 2 WINDOW 3 59 75 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V6 SYMATTR Value 5 SYMBOL voltage -112 -240 R0 WINDOW 0 66 41 Left 2 WINDOW 3 59 75 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V7 SYMATTR Value -5 SYMBOL Opamps\\UniversalOpamp2 -992 192 R0 WINDOW 0 -79 45 Left 2 SYMATTR InstName U2 SYMATTR Value2 Avol=1Meg GBW=4Meg Slew=1.25Meg SYMBOL diode -1008 32 R0 WINDOW 0 -52 13 Left 2 WINDOW 3 -64 45 Left 2 SYMATTR InstName D2 SYMATTR Value DPV SYMBOL diode -1008 368 R0 WINDOW 0 -54 15 Left 2 WINDOW 3 -63 49 Left 2 SYMATTR InstName D3 SYMATTR Value DPV SYMBOL res -704 224 R0 WINDOW 0 56 43 Left 2 WINDOW 3 52 78 Left 2 SYMATTR InstName R7 SYMATTR Value 150 SYMBOL cap -960 -160 R90 WINDOW 0 -57 29 VBottom 2 WINDOW 3 -46 32 VTop 2 SYMATTR InstName C2 SYMATTR Value 2n SYMBOL res -768 -160 R90 WINDOW 0 -56 53 VBottom 2 WINDOW 3 -44 54 VTop 2 SYMATTR InstName R10 SYMATTR Value 1meg SYMBOL res 464 256 R0 WINDOW 0 56 36 Left 2 WINDOW 3 46 71 Left 2 SYMATTR InstName RL SYMATTR Value 1Meg SYMBOL res -832 480 R90 WINDOW 0 -52 49 VBottom 2 WINDOW 3 -43 48 VTop 2 SYMATTR InstName R4 SYMATTR Value 1 SYMBOL res -832 -32 R90 WINDOW 0 -41 52 VBottom 2 WINDOW 3 -36 53 VTop 2 SYMATTR InstName R5 SYMATTR Value 1 SYMBOL res -768 336 R180 WINDOW 0 52 81 Left 2 WINDOW 3 45 44 Left 2 SYMATTR InstName Rq SYMATTR Value 10K SYMBOL voltage -1616 304 R0 WINDOW 0 19 168 Left 2 WINDOW 3 -35 266 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V8 SYMATTR Value PULSE(0 5 1m 1u 1u 10m) SYMBOL res -1440 192 R90 WINDOW 0 -57 55 VBottom 2 WINDOW 3 -49 54 VTop 2 SYMATTR InstName R12 SYMATTR Value 13K SYMBOL res -1376 368 R180 WINDOW 0 61 58 Left 2 WINDOW 3 55 19 Left 2 SYMATTR InstName R13 SYMATTR Value 100K SYMBOL cap -1408 400 R0 WINDOW 0 -64 27 Left 2 WINDOW 3 -70 59 Left 2 SYMATTR InstName C4 SYMATTR Value 18n SYMBOL cap -912 240 R0 WINDOW 0 -46 14 Left 2 WINDOW 3 -44 49 Left 2 SYMATTR InstName C3
TEXT -312 -8 Left 2 ;PV COUPLER TEXT 384 -24 Left 2 ;BIPOLAR HV AMP TEXT 368 32 Left 2 ;J Larkin Oct 9, 2015 TEXT -800 624 Left 2 !.tran 50m TEXT 40 -152 Left 2 ;IXTY02N120P TEXT -8 336 Left 2 ;IXTY02N120P TEXT -296 32 Left 2 ;TLP191B TEXT -312 424 Left 2 ;PV COUPLER TEXT -296 464 Left 2 ;TLP191B TEXT 368 192 Left 2 ;+-300 V TEXT 360 88 Left 2 ;OVERALL GAIN = +50 TEXT -856 584 Left 2 !.model DPV D(Vfwd=1)