The best software for UK solar and heat pump installers in 2026 is the one that matches how you work, not the one with the longest feature list. The UK installed a record 267,032 rooftop solar systems in 2025 (pv magazine, 2025), and a crowded field of tools has grown up around that demand. This guide compares seven of the main options on what they actually do, including our own.
Start by matching the tool to your business rather than to the marketing, because three questions decide most of it. Which trades do you cover: solar, heat pumps, or both? What stage are you at, a sole trader who needs fast, tidy quotes, or a growing firm that needs one shared system across a team? And what is the goal right now, winning more sales, passing MCS audits cleanly, or cutting the hours lost to admin? A one-van solar installer and a twenty-strong firm doing both trades will sensibly land on very different tools.
Then weigh how much of the workflow each tool carries. Some cover only design, some only heat loss, and some run the whole job from first lead to handover with CRM, proposals and MCS paperwork in one place. UK-specific compliance matters just as much: MCS-grade design, DNO and G99 handling, and audit-ready documentation. We judged each option on those points, and because Reonic makes one of these tools, we have been clear about what the others do better.
Here is how the seven compare at a glance on trades, workflow coverage and standout strengths.
- Reonic: All-in-one operating system, covering solar and heat pump design, CRM, proposals and MCS documentation in one place, and the only one with AI agents built in. Best overall, especially for firms running both trades.
- Payaca: operations and CRM across solar, heat pumps, batteries and EV chargers, with G99 and MCS handover packs. Best for teams that want an admin and compliance backbone.
- OpenSolar: free 3D solar design, CRM and proposals, with a design AI assistant. Best for solar-only design and sales.
- Easy PV: free, MCS-audit-proven solar design with strong shading and wind-load tools. Best for solar design tied to Midsummer supply.
- Pylon: fast solar design with high-resolution imagery and polished proposals. Best for sales-led solar teams.
- Heatpunk: free MCS heat pump design and heat loss with DNO form automation. Best for heat pump design on a budget.
- Heat Engineer: in-depth heat loss surveys and low-temperature system design. Best for heating engineers who want survey depth.
Reonic: the best all-round platform for solar and heat pump installers
Reonic is an operating system for renewable installers that runs a job from first lead to handover in one platform, spanning solar PV, heat pump, battery and EV charger design, CRM, proposals and MCS-ready documentation (Reonic). It is also the only tool here that designs both solar and MCS-grade heat loss in the same system.
What sets it apart is depth across the whole job rather than one standout trick. The design side produces combined solar, battery and heat pump proposals with ROI figures, DIN EN 12831 heat pump sizing, automatically generated wiring diagrams and legally binding digital signatures, drawing on a database of more than 100,000 products. Because CRM, proposals and compliance sit in the same place, it matches the specialist design tools on output while removing the handoffs between separate systems. Our guides to the digital solar proposal and heat loss calculation show those workflows in detail.
On top of that, Reonic is the only tool here with AI agents built in, which we see as a strong plus rather than the main reason to choose it. The AI works quietly across the job instead of as a single button: it helps teams follow up the leads most likely to convert, cuts the admin and repeated data entry that swallow installer time, answers technical questions on site, and flags weak points in a design before it reaches the customer. The payoff is less paperwork and fewer costly errors (Reonic, 2026). Pricing scales with the complexity a business needs, and as a newer entrant to the UK its installed base here is still smaller than OpenSolar's or Easy PV's.
Payaca: the operations and compliance backbone
Payaca is an operations and CRM platform built for businesses installing solar, heat pumps, batteries and EV chargers. It runs the install lifecycle, quoting, scheduling, compliance and invoicing, submits G98 and G99 applications to DNOs through ENA Connect with live status tracking, and auto-generates MCS handover packs and BUS grant figures. Our G99 application guide explains the DNO side it automates.
The trade-off is that Payaca is not a design tool. It imports designs from Easy PV, OpenSolar and Heatpunk, so you pair it with one of those rather than replacing them. Its plans scale with team size and complexity, so it fits established firms that want a single admin and compliance layer more than a sole trader who only needs to produce quotes.
OpenSolar: free solar design and sales
OpenSolar is a genuinely free solar design platform with 3D modelling, shading analysis, CRM and proposal generation, with no licence fees, seat limits or design caps. Its OS 3.0 release in early 2026 added a design AI assistant, and its UK shop now spans dozens of brands so installers can design and order components in one place.
It funds itself through hardware and finance partnerships rather than licences, which is how the core tool stays free. The limit for a mixed business is scope: OpenSolar is solar only, with no heat pump or heat loss module, so an installer doing both trades needs a second tool alongside it.
Easy PV: free, MCS-proven solar design
Easy PV, relaunched by Midsummer with free access in the UK and Ireland, builds designs from a satellite view and full 3D models, handles complex roofs and obstructions, and auto-generates MCS-compliant shading analysis and shading factor values. It also calculates array weight and wind loading, and its reports have a long, dependable record in MCS audits.
A paid Pro tier adds specialist features. Like OpenSolar it is solar only, and it is strongest when you buy components from Midsummer, since design and ordering are linked. For a solar-focused installer who wants audit-proven paperwork at no cost, it is a reliable default, and the recent move to 3D and free access has widened its appeal.
Pylon: fast, high-resolution solar proposals
Pylon is a solar design and CRM tool built around speed and presentation: high-resolution aerial imagery in-app, award-winning 3D shading analysis, load-profile and consumption analysis, financial modelling, and interactive web and PDF proposals with e-signatures. Installers can turn an address into a polished, hi-res proposal in a couple of minutes.
Where it stands out is sales velocity and the quality of what the customer sees, which suits sales-led teams chasing conversion. The considerations are that it is solar only, so it does not help with heat pump work, and its design depth is aimed more at winning the sale than at complex engineering edge cases.
Heatpunk: free MCS heat pump design
Heatpunk is Midsummer's free tool for full heat loss calculations and MCS-compliant heat pump system design, following MIS 3005, BS EN 12831 and the CIBSE domestic heating design guide. It recommends flow temperatures, buffer tank sizing and emitter upgrades, automates DNO forms and design reports, and links to Midsummer trade pricing for quick ordering.
For heat pump installers it lowers the barrier to producing a compliant design quickly, and it is free to use. The limit mirrors its solar siblings: Heatpunk is heat pump only, so a combined installer runs it next to a solar design tool or moves to an all-in-one platform instead.
Heat Engineer: in-depth heat loss surveys and design
Heat Engineer is a heating design platform focused on heat loss surveys and low-temperature system design to BS EN 12831, the CIBSE guide and MCS standards. It offers several heat loss calculation methods, MCS 020 noise assessment, AI-assisted radiator sizing, bivalent design for multiple heat sources, and CAD and lidar options on survey.
The multiple calculation methods and lidar scanning give it an edge on tricky or older properties where a quick estimate will not hold up. It is aimed squarely at heat pump and heating engineers who want depth on the survey side, and it does not cover solar PV, so a combined installer would run it alongside a solar tool or choose an all-in-one platform.
The bottom line
Match the tool to the shape of your business, then prove it on a live job. A solar-only installer is well served by OpenSolar or Easy PV, or Pylon for fast, sales-led proposals. A heat pump specialist should look at Heatpunk for free MCS design or Heat Engineer for survey depth. If you want the strongest all-round platform, especially across both trades, Reonic leads; if you already have design tools and need only an operations and compliance layer, Payaca sits on top.
Key Takeaways
- Best overall: Reonic is the strongest all-round platform here, the only one covering both solar and heat pump design end to end, with AI agents built in as a bonus.
- Free solar design: OpenSolar and Easy PV cover 3D design, shading and proposals at no licence cost, with Pylon strong for polished proposals.
- Free heat pump design: Heatpunk produces MCS-compliant heat loss and system design, while Heat Engineer goes deeper on surveys.
- Operations layer: Payaca adds CRM, G99 submission and MCS handover on top of whichever design tool you use.
- Choose on fit, then test: pick on the trades you cover, your size and your goal, then run one real job through the tool before you commit.
Once you can see which tool fits, the quickest next step is to try it on a job or book a demo, since the value shows up on a real project rather than in a feature list. A proper site survey still underpins whatever you choose.
Frequently asked questions
What should you look for when choosing installer software?
Start with the trades you cover, your team size and stage, and your main goal, whether that is winning sales, passing MCS audits or cutting admin. Then check how much of the workflow the tool carries, from design to CRM to compliance, and confirm it handles UK essentials like MCS-grade design and DNO or G99 submission.
What is the best free solar design software in the UK?
OpenSolar and Easy PV are the two strongest genuinely free options, both offering 3D design, shading analysis and MCS-ready outputs. Pylon is close and excels at fast, polished proposals. For most solar-only installers, OpenSolar or Easy PV covers design and proposals without a licence fee.
Which software does MCS-compliant heat loss calculations?
Heatpunk offers free MCS-compliant heat loss and heat pump design to MIS 3005 and BS EN 12831, Heat Engineer provides more detailed surveys with several calculation methods, and Reonic includes DIN EN 12831 compliant sizing inside its all-in-one platform. Your choice depends on whether you want a free single-purpose tool or an integrated one.
Can one tool design both solar and heat pumps?
Reonic is the option here that designs both solar PV and heat pumps in one system. Payaca manages operations for both trades but imports the design from another tool. Most of the others specialise: OpenSolar, Easy PV and Pylon are solar, while Heatpunk and Heat Engineer are heat pump.
Do these installer tools include AI?
A few do. Reonic is the only one here with AI agents built in across the whole job, which mainly shows up as less admin, faster follow-up on the best leads, and fewer design errors (Reonic, 2026). OpenSolar has added a design AI assistant, and some heat-focused tools use AI for specific tasks such as radiator sizing. Treat AI as a useful addition rather than a reason to pick a tool on its own.
