Anyone else getting wildly different yield figures between Victron MPPT and a clamp meter on the DC cable?

Been scratching my head over this for a few weeks now. My Victron SmartSolar 100/30 is reporting daily yields of around 180–210Wh on a decent sunny day, but when I stick my clamp meter on the positive DC cable between the controller and the battery bank, I'm consistently reading 10–15% higher current than what the Victron app is logging. Running 2x 175W Renogy panels in series into a 200Ah Fogstar Drift LiFePO4.

I've calibrated the clamp meter against a known resistive load and it's spot on. The Victron is on the latest firmware (v3.14). My shunt is a Victron SmartShunt 500A wired correctly on the negative, and that actually agrees pretty closely with the clamp meter rather than the MPPT figures — which makes me think the controller itself is under-reporting rather than the clamp meter being off.

Has anyone dug into this before? Is there a known offset in how the SmartSolar calculates yield — maybe averaging current over PWM switching cycles in a way that loses accuracy? Or could there be a wiring issue between the MPPT output and the shunt that's introducing a phantom path? Would really like to understand the root cause before I start trusting either figure for my system sizing calculations.

@BarryWood had exactly this on the Mabel Rose last summer. Clamp meter was reading higher than the Victron's logged yield, and I went down a proper rabbit hole over it.

Turned out my clamp meter was picking up noise from the MPPT's switching frequency and inflating the current reading. DC clamp meters vary wildly in quality — mine was a cheapo thing that couldn't handle the pulsed DC properly.

Two things worth checking:

• Where on the cable you're clamping matters more than you'd think — get as far from the controller as possible
• Compare over a full day, not snapshots, because MPPT efficiency losses mount up gradually

The Victron figure is calculated internally from actual charge delivered to the battery, so I'd trust it over a clamp reading personally. What meter are you using?

My clamp meter was reading like my panels were powering a small city whilst the Victron quietly logged something far more modest — turned out the clamp meter was picking up AC interference from a nearby inverter cable running parallel, giving phantom readings; separate your DC cable runs properly and the numbers will likely kiss and make up.