Verified against each vendor’s own pricing page, not inferred from a “free” badge. Six different kinds of “free” exist in this market and this page keeps them apart.
10 products cost nothing to use and 5 more offer a permanent free tier alongside paid plans. Several are published by inverter manufacturers and equipment distributors — the software is free because the hardware is not. A further 6 offer a limited free allowance rather than a full tier.
Verified against the vendor’s own pages.
These products carry no licence or subscription fee at all.
KACO new energy GmbH
Design & simulation · Web
A free, no-login, browser-based PV sizing and yield tool that KACO new energy (a Siemens company) puts its brand on, and that Valentin Software builds and hosts — the same company behind PV*SOL.
OpenSolar Inc.
Proposals & sales · Web
A free-to-use solar design, proposal and project-management platform funded by manufacturers, financiers, distributors and other partners rather than by the installers who use it.
European Commission, Joint Research Centre (JRC)
Design & simulation · Web
The European Commission's free web tool and API for solar radiation and PV performance anywhere on Earth — grid-connected, tracking and off-grid performance, monthly, daily and hourly radiation, and a downloadable TMY — with no account, no key and no usage restriction.
PVOutput.org (community)
Monitoring & asset mgmt · Web · iOS · Android
A free, community-run site where solar owners upload their own generation data, compare it with neighbouring systems, and pull it back out through an open API — the honest answer to "is there free solar monitoring", and not a product in the sense the rest of THE 100 are products.
Renvu
Distributor design tools · Web
A US solar distributor's in-store configurator that walks you from roof type and panel count to a fully engineered, priced bill of materials — racking, BOS, connectors, labels and all — and then lets you buy it, with no login required to reach the quote.
National Laboratory of the Rockies (NLR) — formerly the National Renewable Energy Laboratory (NREL)
Design & simulation · Desktop
The US national laboratory's free, open-source desktop techno-economic model — PV, CSP, wind, marine, geothermal, biomass, solar water heating and storage, each wired to a full project-finance model (PPA, partnership flip, leaseback, TPO, community solar, merchant plant).
Segen Ltd
Distributor design tools · Web
Free design, configuration and quoting tools inside the Segen trade portal — Quick Quote builds a priced UK solar parts list from a few multiple-choice answers, and a newer Google-Solar-API-based Design Tool is announced but not yet shipped.
SolarEdge Technologies
Design & simulation · Web
SolarEdge's free browser-based PV design and proposal tool — HD imagery, AI-assisted 3D roof modelling, automatic panel placement, automatic stringing and DC cabling, and a customer proposal with financial analysis — with no licence or subscription fee.
Tigo Energy, Inc.
Monitoring & asset mgmt · Web · iOS · Android
The commissioning and monitoring portal that ships with Tigo TS4 module-level electronics — free at the base tier, with a $20/yr per-site upgrade for minute-level data and API access and a $199/yr company plan for fleet management.
Racking design · Web
U-Builder is Unirac's free, login-gated browser configurator that lays out an array, sizes Unirac racking to ASCE 7, and returns a BOM, an engineering report and a state certification letter — with GO as the fast quoting path and PRO as the permit-design path.
Paid plans exist, but a free tier runs indefinitely rather than expiring.
Bodhi
Customer experience · Web
A white-labelled homeowner communication and project-tracking layer that a solar installer buys and puts its own brand on, to cut cancellations and escalations and to generate reviews and referrals after the sale.
Demand Manager
Compliance & rebate · Web
An Australian certificate aggregator and AFSL-holding trader whose free LightWork apps (Commercial, Residential, Solar) capture the compliance evidence for ESC, VEEC, STC, PRC and REPS claims, monetised through an undisclosed success fee on the certificates it creates and trades.
Midsummer
Design & simulation · Web
A UK-only, MCS-oriented solar design and sales tool that is free at the base tier and £35/month for Pro, published by a solar wholesaler — so the kit list it produces drops straight into a trade order with live pricing and next-day delivery.
Heaven Softech Pvt. Ltd.
Publisher’s partner — never ranked
CRM & lead management · Web · iOS · Android
Glytrix
CRM & lead management · Web
An Australian solar CRM with design, proposals and invoicing built in, metered on a monthly token allowance rather than on seats or projects.
A metered quantity of free usage — requests, credits or projects — rather than an open tier.
Green Energy Trading Pty Ltd
Compliance & rebate · Web · iOS
Pylon
Proposals & sales · Web
Clean Power Research, L.L.C.
Weather, tariff & utility data · Web
Solcast
Weather, tariff & utility data · Web
Transect
Site selection & GIS · Web
UtilityAPI
Weather, tariff & utility data · Web
Two states that a “has free trial” checkbox would get wrong.
The trial is paid
Yes. 10 products in this dataset cost nothing to use, and 5 more offer a permanent free tier alongside paid plans. Several are published by hardware vendors and distributors, where the software is paid for in equipment margin.
Usually the business model. Manufacturer and distributor tools are free because they sell equipment; some restrict designs to their own hardware, and some do not. Where a vendor does not state whether third-party hardware can be used, we record that silence rather than guessing.
No, and we keep six states apart. 1 product's "trial" costs money, and 6 vendors offer demos rather than trials. A boolean "has free trial" field would misrepresent all of them.
