Energy loss waterfall

ID: concept:energy-loss-waterfall
IRI: https://solarlattice.org/kb/concept/energy-loss-waterfall
Status: active
Also known as: loss waterfall, loss tree, loss factors, Performance Waterfall, pv energy losses waterfall, VI Performance Waterfall
Category: Monitoring
Concept kind: technology

An energy loss waterfall is a chart that breaks PV production losses into categories and shows them against actual production and baseline estimates, so you can see quickly where performance is falling short. On the left side it steps from estimated energy, meaning the budget or pro forma, to expected energy, meaning modeled ideal output. In between are an insolation adjustment, degradation and other modeling differences. On the right side it steps from expected energy down to measured energy, using detected losses such as snow, soiling, curtailment and downtime, plus an 'other' bar for unexplained losses and uncertainty. Model-based versions can also show clipping, shading, partial capacity or string outage, and degradation losses, estimated daily by comparing modeled and measured data. The results are only as accurate as the PV model and the irradiance and module temperature data feeding it, so a well-tuned model and good sensors are essential. Losses such as shading, thermal, clipping and inverter efficiency can be part of both the estimated and the expected energy. In that case they do not appear as differences on the estimate-to-expected side of the waterfall. Comparing losses against configured or contractual loss allowances helps owners explain underperformance and check whether site agreements are being met.

<!-- review notes

sentence 7: support check: partial - Passages support explaining underperformance and compliance with contractual agreements, and contractual comparison, but the exact framing of checking against allowances is somewhat inferred. -->

Parts

Clipping loss

Claims

The Energy Loss Waterfall is a visual analysis tool under the PowerTrack Analysis tab.

9 energy loss waterfall sec=front h=3eaf52f980fb
PowerTrackUserGuide RevA 1.25 sec=7.3 h=cf46db96b935

c2 drafted · lead Clipping loss

Clipping is one of the loss categories; PowerTrack separates it from Inverter Limit loss at 96% of rated output.

PowerTrackUserGuide RevA 1.25 tbl=10.r2 h=0372516e81ca
vi performance waterfall overview sec=h2 h=c6fba6569d7a
vi performance waterfall overview sec=h12 h=66cfaabb55b0
PowerTrack PV Model Losses sec=h4 h=922439f95406

c3 drafted · lead Shading loss

vi performance waterfall overview sec=h2 h=c6fba6569d7a
PowerTrackUserGuide RevA 1.25 tbl=10.r6 h=c69a93783ca9
vi performance waterfall overview sec=h8 h=30e070dc9187

c4 drafted · lead Soiling Losses

vi performance waterfall overview sec=h2 h=c6fba6569d7a
vi performance waterfall overview sec=h10 h=0e53afbc7459
PowerTrackUserGuide RevA 1.25 tbl=10.r8 h=d0ec4e1591d7

c5 drafted · lead Snow Accumulation Yield Losses

9 energy loss waterfall sec=front h=3eaf52f980fb
energy loss waterfall sec=front h=b18a92c492b3
vi performance waterfall overview sec=h2 h=c6fba6569d7a

c6 drafted · lead Curtailment

energy loss waterfall sec=front h=b18a92c492b3

c7 drafted · lead Availability

Downtime loss covers periods with no production while the model predicts output and no significant snow is present.

vi performance waterfall overview sec=h6 h=c07210b8eb97
PowerTrackUserGuide RevA 1.25 tbl=10.r4 h=6df027c801f8

review note: support check: partial - Downtime loss definition matches the note, but availability as a metric is not mentioned; downtime loss is only implicitly related.

c8 drafted · lead Degradation rate