FAQs
Frequently Asked Questions
Why use Denowatts?
The value proposition of Denowatts is to bring better performance insight to the solar industry. Denowatts delivers valuable business intelligence to our members thanks to focusing on day-to-day energy accounting and performance testing. Denowatts developed advanced Deno DTB technology to provide these services faster, more accurately, and more efficiently than traditional methods. The net result of our data stack is superior performance insight for less cost.
For about the cost of a traditional weather station, Denowatts provides streamlined benchmarking sensors, site equipment data ingestion, ISO 17025 Accredited Capacity Testing, and five years of energy accounting. Owners and operators benefit from a fast, efficient, and accurate way to manage a single project or a growing portfolio. Denowatts members benefit from business intelligence and performance insights to optimize solar performance.
Denowatts is not a full-service monitoring company. Instead, Denowatts deploys self-service monitoring core technology and focuses on capacity testing and day-to-day energy accounting to deliver performance insight to any monitoring or ERP platform.
Denowatts interfaces with any monitoring service locally via Modbus TCP and API. Denowatts API may benefit enterprise resource planning (ERP) software since it contains Deno CleanTM data, which is time-series data that characterizes performance in energy accounting terms.
Denowatts technology cost-effectively scales from 100 kW rooftop to 200+ MW tracking systems. The typical project size is 2-6 MW.
Two fundamental steps to onboard Denowatts are: 1) Deploying the Deno DTB technology and 2) Establishing the performance model. Denowatts typically ship hardware in about a week. While the hardware is shipping, project managers upload the energy model and system design documents so Denowatts personnel can prepare the configuration. Certified Installers can install Deno DTB on a typical site in 2-4 hours. Once installed, Denowatts personnel support remote sensor commissioning. A 1-hour Installer Certification is available on Heatspring for free and is highly encouraged before a first installation. Project Managers may also take a 1-hour course on Heatspring to understand the entire process from Request for Quotation through Capacity Testing.
How does it work?
Deno Digital Twin Benchmarking (DTB) technology is a core technology that consists of wireless and self-powered sensors, edge computation, and site data ingestion. Deno DTB technology utilizes the expected power model at the grid edge to provide performance management with unparalleled resolution and accuracy.
Denowatts recommends watching the Science of Denowatts for a basic understanding of the Deno DTB technology and performance management methodology. This includes a self-guided Overview of the Denowatts service.
Deno DTB replaces traditional weather stations by providing the most critical elements of benchmarking data collection: irradiance and module temperature. Deno DTB sensors are small, self-powered, and wireless, which allows for accurate benchmarking for simple to very complex site requirements of any scale.
The Deno sensor is not an ISO 9060 Flat Spectrum Class A pyranometer. If the customer’s requirement dictates, a Class A pyranometer may simply be plugged into a Deno sensor to report flat spectrum irradiance and perform capacity testing. Most importantly, Deno sensors are specifically designed to report reference irradiance. Unlike broad-spectrum irradiance, reference irradiance is a measurement that targets the spectral and reflection responsivity of the solar modules under test.
The better question to ask is, what are you trying to measure? For day-to-day high-resolution performance testing and energy accounting, utilizing a reference device like a Deno DTB results in lower measurement uncertainty, primarily because of matching spectral and reflection response and response times. The best sensor depends on the contractual test boundary requirements for end-of-construction capacity testing, including ASTM E2848 or IEC 61724-2 procedures. Denowatts recommends reviewing the DNV Technical Assessment for further details.
Deno sensors have a typical measurement uncertainty (K=2) of 1.0%. Denowatts is an ISO/IEC 17025 Accredited Calibration and Testing Laboratory with a scope that includes the calibration of Deno pyranometers with a Calibration and Measurement Capability (CMC) of 1%.
Denowatts recommends recalibration every five years, though it requires calibration within two years for record capacity tests. While five years is longer than conventional guidelines, Deno DTB technology includes the ability to track the calibration drift of all Denowatts sensors, enabling the reporting of measurement uncertainty based on the sun-age of the sensor. For example, a newly installed sensor with only 100 Sun-hours will have a calibration uncertainty as reported by the certificate (typically 1.0%, k=2). However, a Deno sensor in the field for three years will have a calibration uncertainty that includes an observed drift error of approximately .5% /1,500 sun-hours, or a combined 2% (k=2). Users may request a recalibration at any time to meet their requirements for measurement uncertainty, though Denowatts encourages sensor recalibration every five years. To obtain a recalibration, Denowatts ships a new sensor to the customer for a discounted price, which includes a new 5-year warranty.
Deno sensors utilize dual photodiode-based pyranometers, technically termed ISO 9060 (2018) Fast Response Pyranometers. Denowatts selected this technology because of its stability, accuracy to reference irradiance, response time, and form factor. Unlike larger reference cells, photodiode-based pyranometers benefit from more stable packaging and can be tuned to optimize spectral and reflection response.
Effective irradiance is the amount of sunlight that is absorbed by the PV modules for power conversion. The difference between broad spectrum incident (often called “POA”) and Effective irradiance is losses due to spectral, reflection, shading, and soiling.
Energy models have two primary inputs: Effective (absorbed) irradiance and cell temperature. The closer the sensor measurements are to these model inputs, the better the reproducibility of results (i.e., standard error). The reason for better reproducibility of results is that modeling assumptions about spectral and reflection losses are replaced by actual measured values with known uncertainties. Further, the Denowatts Learned Shade Profile replaces customer model shade assumptions.
Customers upload their asset’s record energy model during the onboarding process, often PVSyst, Helioscope, PlantPredict, Daly Energy, and others. Denowatts uses the model parameters to construct a Proxy Model for day-to-day energy accounting. The Proxy Model typically utilizes the Single Diode PV model (PVLib) and other traditional components. The Proxy Model is first validated against the customer’s Predicted model using the predicted resource data sets to ensure proper accuracy and accounting for all production and loss assumptions.
Denowatts warranties Denos for up to 5 years with a current service subscription. Denowatts encourages the replacement of Denos every five years as a best practice to maintain optimal calibration and reliability.