Been there with my narrowboat setup — 200W is tight for overnight draw. What's your battery capacity and what's actually consuming power after dark? That's usually where the issue sits.
I ran 200W with a 100Ah lithium for a while and quickly realised the problem wasn't the panels, it was phantom loads. Fridge, inverter standby, solar controller standby — it all adds up. Even a modest 20W draw overnight will hammer a battery over 12 hours.
Few things worth checking:
- Actual discharge rate — measure it properly with a multimeter on the battery itself, not guessing. Get a sense of what's running when you're sleeping
- Controller choice — if you're using a PWM instead of MPPT, you're losing efficiency, though that's mainly a daytime issue
- Battery chemistry — how much of your capacity are you actually usable? Lithium behaves completely differently to lead-acid
- Panel orientation — 200W nominal is optimistic. Real-world output depends heavily on angle and season
I've since moved to 400W on the boat and it's noticeably better, but honestly the battery upgrade made the bigger difference. Added a second 100Ah and suddenly overnight discharge stopped being the limiting factor.
What's your current setup — lithium or lead-acid, which controller, and roughly what's the overnight drain in amps? That'll help narrow down whether this is a solar problem or a consumption problem. Usually it's the latter.