Solar panels, also known as photovoltaics (PV), are an assembly of silicon cells mounted in a frame with wiring that helps absorb and convert sunlight into usable electricity. When light hits a silicon cell, the light causes electrons in the silicon to be set in motion, initiating a flow of electric current. Wires capture and feed this direct current (DC) electricity to a solar inverter to be converted to alternating current (AC) electricity. This is known as the “photovoltaic effect.”
(Source: EnergySage.com, Solar-101)
Solar panels can be used for a wide variety of applications including remote power systems for cabins, telecommunications equipment, remote sensing, and of course for the production of electricity by residential and commercial solar electric systems.
Solar Panel Surface Area
Solar Panel Surface Area is the total array area for PV modules. It does not include additional area that may be required for space between modules or for inverters, etc. Area will be related to the total array kW based on the power per module that make up the array. There are two ways to calculate the total array power depending on information you have available.
A) Using the array size and an assumption of 1 kW / sqm for the modules follow this equation. Use this equation in reverse to find the array size based on the kW.
Size (kW) = Array Area (m²) × 1 kW/m² × Module Efficiency (%)
Size (kW) = Array Area (ft²) × 0.092903 kW/ft² × Module Efficiency (%)
B) Using the module nameplate size and number of modules follow this equation. Use this equation in reverse to find the array size based on the kW.
Size (kW) = Module Nameplate Size (W) × Number of Modules ÷ 1,000 W/kW
C) Another great option is to use the National Renewable Energy Laboratory (NREL) PVWatts Calculator. Here you will find the Rooftop Size Estimator to help you determine an array size for an existing building.
Solar Panel Angle
The performance of solar panels changes based on their angle. Find out the optimal angle orientation for your location using the Solar Angle Calculator from the Solar Electricity Handbook.
Note the input requires an angle degree from the vertical.
If you cannot change the angle of your panel throughout the year, angle your panel according to the time of year that you need to get the best performance out of your system. For North America, this will be wintertime.
If you live in the northern hemisphere, you would point your panels due south to capture the maximum amount of sunlight. Also, if you live in the southern hemisphere, you would point your panels due north.
Most homeowners with solar energy systems mount their panels in a fixed position, where the panels can be manually tilted as needed. Find out more about how to calculate the solar panel angle for summer and winter here.
Solar Panel Module Location
Solar Panel Module Location is the installation location of the panel, varying between 'cladded on the roof' vs 'on a frame' can impact how ventilated it is which impacts its performance.
analysis.tool uses to the EN 15316-4-6 Table B.4 for the 'Solar Panel Module Location' factor calculation. The 'Solar Panel Module Location' is a factor that takes into account the system performance of the building integrated photovoltaic installation depending on:
Conversion system from direct current to alternating current.
Actual operation temperature of the photovoltaic modules.
Building integration of the photovoltaic modules.
The distinction between different building integration could be according to the type of ventilation of the photovoltaic modules. The values for the different types of 'Solar Panel Module Location' factors can be found in the table below:
Solar Panel Module Type
Solar Panel Module Type, is the material characteristics of the module which significantly impact the efficiency of the panel.
Mono Crystalline Silicon: Mono Crystalline panels are created from a single continuous crystal structure. Monocrystalline panels are the oldest, most developed, and most expensive of the three technologies. Monocrystalline achieves the most efficient sunlight conversion rates, with efficiency averages from 15 to 20-percent.
Multi Crystalline Silicon: Multi Crystalline solar panels (aka. polycrystalline) are made from silicon, similar to their Mono Crystalline counterparts. Instead of using a single crystal of silicon, many fragments of silicon together to form the solar panels. Multi Crystalline solar modules contain many crystals in each cell, which inhibits the movement of electrons and leads to lower efficiency compared to mono modules.
Thin Film Silicon: Thin Film Silicon cells are made by depositing one or more thin layers of silicon on a substrate such as glass, plastic, or metal.
Other Thin Film: Thin Film solar cells are made by depositing one or more thin layers of photovoltaic material on a substrate such as glass, plastic, or metal.
Thin Film Copper: Copper Gallium Indium Selenide solar cell is one of the three mainstream thin-film technologies with a lab efficiency above 20%.
Thin Film Cadmium: Cadmium Telluride solar cell is one of the three mainstream thin-film technologies with lab efficiency above 20%. CdTe has the lowest Energy Payback time of all mass-produced PV Technologies.
Thin Film Perovskite: Thin Film Perovskite solar cells have shown potential for high performance and low production costs. (Note: not commercial/ still in R&D)
Organic: Organic PV is a rapidly emerging PV technology with improving cell efficiency (currently 11% certified)
Solar Panel Type | Efficiency |
Thin Film, Copper (CIGS) | .192 |
Thin Film, Silicon (a-Si) | .102 |
Thin Film, Cadmium (CdTe) | .195 |
Thin Film, Perovskite | .237 |
Thin Film, GaAs | .251 |
Organic | .087 |
Multicrystalline Silicon | .204 |
Monocrystalline Silicon | .244 |
PERC | .245 |
Perovskite | .179 |
TOPCon | .257 |
IBC | .261 |
FAQ
What are the differences between Solar Hot Water and Solar Panels?
Aside from using photovoltaics to generate electricity, solar energy is commonly used in thermal applications to heat indoor spaces or fluids. Residential and commercial property owners can install solar hot water systems and design their buildings with passive solar heating in mind to fully take advantage of the sun's energy with solar technology. While solar panels can be used to fuel any electrical equipment, solar hot water systems specifically used solar power to heat water. Learn more about solar hot water here.
Can we use this for the PV tax rebate?
Depending upon where you live, several rebates or incentives for solar power may contribute towards lowering the cost of having solar energy. Nationwide, the federal Investment Tax Credit (ITC) is one of the primary incentives available to anyone interested in solar energy, as it allows you to deduct 26 percent of the cost of installing a solar system from your federal taxes. analysis.tool can help you identify the need of PV and design/size of a particular array, however, pursuing to earn the tax rebate the documentation process requires a more advanced workflow.
Can we model solar energy + battery storage with cove.tool?
Currently analysis.tool does not include battery storage capability. For anyone not familiar, given that solar panels can only produce power when the sun is shining, storing produced but unused energy throughout the day for use at a later time has become increasingly important. For instance, solar batteries store electricity and can be drawn on during periods of low solar production. What’s more, solar-plus-storage solutions work for all scales of solar panel installations and provide many added benefits, from energy reliability to grid resiliency and lower-cost power.
What tool can I use for more detailed PV design?
analysis.tool provides a predictive input for described here with its energy analysis for the schematic design stage. To get a detailed accurate information about the PV system for your final design, definitely talk with a qualified PV consultant or use tools like PVsyst, Helioscope, and System Advisor Model (SAM) that are specifically designed for PV design and analysis.
Does analysis.tool have a 3D Analysis for PV design? Can I test where the best PV placement is and much kW I will generate from the placement?
No, we calculate PV energy as a area input - not via 3D placement. On the baseline energy page, you will enter inputs of your PV strategy, but those will manually calculate EUI reduction and is independent of placement on the building. Due to having no 3D component, there is no way to account for this currently in the app. However, the Radiation and Sunhours analysis will provide what facade surfaces will have the best PV placement through High Radiation and a High number of sunlight hours on the 3D analysis page.