Earth Notes : On Tools for Solar PV/Thermal Projects Learn about some tools helpful when considering/designing a solar PV or thermal system for the UK. #solar #tools #microgen
There are many calculators available on-line (and off-line) to help with solar design. This outlines a selection and lists many more!
On-line Calculators Midsummer Energy provides a simple UK PV solar panel calculator for example, which I have often used.
PVGIS Another good tool is the PhotoVoltaic Geographical Information System (PVGIS) . PVGIS "provides a map-based inventory of solar energy resource and assessment of the electricity generation from photovoltaic systems in Europe, Africa, and South-West Asia."
The model algorithm estimates beam, diffuse and reflected components of the clear-sky and real-sky global irradiance/irradiation on horizontal or inclined surfaces. The total daily irradiation [Wh.m-2] is computed by the integration of the irradiance values [W.m-2] calculated at regular time intervals over the day. For each time step during the day the computation accounts for sky obstruction (shadowing) by local terrain features (hills or mountains), calculated from the digital elevation model. Spreadsheet Calculators It is often useful to be able to work off-line. Even if one is not actually perched on a roof top when trying to add up on fingers and toes!
Julian Pearson volunteered me his own (Excel) spreadsheet that calculates the duration of sunlight per day, at the latitude entered by the user, as well as the angle of the sun... works out the efficiency of the solar strike on the panel for each day of the year ... [it assumes] optimised conditions ... [with an unobstructed, unshaded] clear view south.
He is happy for it to be distributed and used for free as long as the usual courtesies are respected. No messing with it, no charging for it or for use of it, and attribution for his work and that of the people he mentions in the spreadsheet.
PC Applications One PC-based (paid-for) tool is the PVSYST PC application "for the study, sizing, simulation and data analysis of complete PV systems."
The installer of my 1.29kWp hybrid PV system used PVSYST to predict output . The graphs and tables are fairly clear and helpful. Sources/Links 2026-09-26 : Tegrona Lite : Free PV layout software: solar modules from a rooftop photograph, without leaving the desk . 2025-01-15 : do not clean solar PV with dishwashing detergent! [poskela2024cleaning ] 2022-01-18 : Best fire safety practices for rooftop PV system installations : The proposed fire safety practices were categorized into 10 groups considering different factors: general practices to ensure the PV system is designed by qualified contractors only; site survey including size, shade management, accessway, tilt, orientation and location; roof structure and material; marking systems for all PV equipment including PV input and output, conduit, cabling, inverter, enclosures, combiner, box, and isolator switches; roof waterproofing and flashing; electrical cabling and grounding system; array mounting, ventilation and PV panels; combiner box and connectors; DC/AC inverter; and DC isolator and other protection devices. https://doi.org/10.1016/j.scs.2021.103637 Shademap displays the sunniest and shadiest locations over the course of a day. Solar PV Panels ... the ethical and environmental record of 19 solar panels . The restful API for solar production forecast data and weather forecast data : as of 2025-03 various public/free and priced plans. Solar resource assessment and forecasting data for irradiance and PV power. Created using a global fleet of weather satellites. Solar panels and solar farms in the UK - geographic open data (UKPVGeo) : see the research paper A harmonised, high-coverage, open dataset of solar photovoltaic installations in the UK . In the UK, around 99% of PV installations are small-scale (<50 kW), and they account for around 30% of the nation's installed capacity. ... As of June 2020, the UK Government reports that the country has 1,037,150 PV installations. See the on-line PVGIS Solar Irradiance Data tool. Underlying PVGIS is the EU's Solar Electricity Action SOLAREC programme (map of solar energy potential in Europe). London, United Kingdom - Sunrise, sunset, dawn and dusk times for the whole year : includes insolation kWh/m^2/d (0.49 in Dec, 4.86 in Jun). London Solar Opportunity Map . Solar Panels - PV System Sizing and Power Yield Calculator . Energy Saving Trust Solar Energy Calculator . RenSMART Solar PV Comparison Table: table of the commonly offered solar pv panels available in the UK Optimum Tilt of Solar Panels . RapidTables Voltage Drop Calculator . The PVSYST PC application "for the study, sizing, simulation and data analysis of complete PV systems." SMA's Sunny Design Web to help design PV systems, including storage. See PV Resources' software roundup . Midsummer Energy 's solar panel calculator suggests that each Wp of panel will generate about 1Wh per day in winter in the UK and about 5Wh/day in the summer (and a yearly average of ~2.47Wh/day), so to cover n Wh of base load year-round might require n Wp of panel, plus maybe 20% for storage and conversion losses, and with a huge excess of capacity in summer. Steve Ransome Consulting : Independent PV consultant. Spreadsheet calculator for optimal panel angle (xlsJulian Pearson . Consolar has a useful sizing guide , for example: allow for 40l/person/day, allow between 80l and 100l per m^2 of collector (other sources suggest as little as 57l/m^2). Plus good sense such as to angle collectors at >45°C to maximise winter output and reduce overheating risk in summer. See Libre Software in Building design . The global standard spectrum (AM1.5g)" . DC vs AC solar PV capacity factors and "Approximate DC capacity factors: 10-13% Germany, 10-12% UK, 15-19% Spain, with the highest without tracking likely about 23% (Atacama Desert, Tibetan plateau). CFs above this are likely to be either AC, or using tracker devices, or both. Note the following handy conversions: 1kWh = 3.6MJ = 3412Btu = 0.03412Therms. How to protect rooftop PV systems from fire risk : The guide ... defines the most common fire causes, such as bad system design, inadequate installation, animals chewing on wires, storm damages, manufacturing faults in PV products, including connectors and junction boxes, and heat accumulation, among others. ... What is also very important if a fire breaks out is that the firefighters can find all information about the existing PV system in the meter cupboard or at the entrance of the building... . From Jack Kelly : Making energy data easier to find . Community energy in England (and Wales) map .
