OpenSolar costs least per proposal, because its core app is free and only your design time and any paid imagery count. Aurora Basic lists $135 per user a month on annual billing ($159 monthly), about $13.50 a proposal at ten a month, and beats manual design from five proposals a month on the time assumptions below.
"Free" covers OpenSolar's core app only. Since 16 April 2026 it has charged for API access, as a fee on each project created, and for its own connectors, with accounting sync at $49 a month, so a firm that links OpenSolar to a CRM or accounts package pays something. Every price comes from the vendors' own pages, read on 29 October 2026. The design times are my illustrations: 90 minutes for a manual proposal and 35 minutes with either tool, at $35 an hour of staff time. Neither vendor publishes an end-to-end time for a finished proposal, so the last section shows how to time three of your own past jobs before you pay for anything.
Prices and limits as Aurora and OpenSolar print them
Four options sit in the comparison: Aurora's Basic and Premium plans, OpenSolar's free core app, and designing by hand. The table lists what the vendors print, plus the extras that can turn a headline price into a different bill.
| Option | Price per month | Limits | Extras that cost money |
|---|---|---|---|
| Aurora Basic | $135 per user on annual billing ($1,620 a year); $159 month to month | 50 projects a month, 1 user | Standard on-demand site models listed from $9.99; Nearmap imagery add-on |
| Aurora Premium | $220 per user on annual billing ($2,640 a year); $259 month to month | 50 projects a month, 1 user | Same as Basic; LIDAR-assisted modelling, bankable shade reports and battery storage modelling are inside the plan price |
| OpenSolar | $0 for the core app | None stated on the pages I read; confirm in your account | Pay-per-image premium imagery; API access billed per project created, after a 30-day free trial; accounting connectors $49 a month; optional support packages from $500 a month |
| Manual design | $0 for software | Your hours | Imagery, an irradiance calculator and a quote template, usually free or already owned |
Aurora's FAQ adds the contract terms. Monthly Basic and Premium have no minimum commitment and cancel at the end of the billing month. Annual plans carry a one-year commitment and cancel at the end of the year. Extra users and extra projects are bought as additional licences in the app, or by moving to Enterprise, which Aurora prices by quote. Aurora's own page calls annual billing a 15% saving, and the arithmetic holds: $159 less 15% is $135.
OpenSolar's position is more nuanced than "free", and the nuance matters for cost. Its pages say the software is free for solar professionals and is paid for by partners such as manufacturers, finance companies and distributors. In February 2026 it announced that from 16 April 2026 two things carry a price: API access, and OpenSolar-built connectors. Staying inside the app costs nothing. Connecting it to a CRM or accounting package does, and that feeds straight into the per-proposal figure.
Cost per proposal at 5, 10, 20 and 40 proposals a month
The assumptions are simple. A manual proposal takes 90 minutes: measuring the roof from imagery, laying out panels, estimating output, pricing and writing it up. With a design tool, a proposal takes 35 minutes. Staff time costs $35 an hour including on-costs. That makes a manual proposal $52.50 and a tool-assisted one $20.42 in time. Aurora's subscription is then divided across the month's proposals, using annual billing.
| All-in cost per proposal | 5 a month | 10 a month | 20 a month | 40 a month |
|---|---|---|---|---|
| Manual design (time only) | $52.50 | $52.50 | $52.50 | $52.50 |
| OpenSolar (time only) | $20.42 | $20.42 | $20.42 | $20.42 |
| Aurora Basic ($135 plus time) | $47.42 | $33.92 | $27.17 | $23.79 |
| Aurora Premium ($220 plus time) | $64.42 | $42.42 | $31.42 | $25.92 |
The software-only part is smaller than it looks and shrinks quickly. Basic is $27.00 a proposal at five a month, $13.50 at ten, $6.75 at twenty and $3.38 at forty. Premium is $44.00, $22.00, $11.00 and $5.50. In every row OpenSolar is cheapest, because the same 35 minutes of time costs $0 in software. That ranking depends entirely on the two tools taking the same 35 minutes, which is why the next section turns the question around.
How many minutes Aurora must save to beat a free tool
A paid tool is worth buying over a free one only if it saves time or wins jobs the free one would not. At $35 an hour, each dollar of subscription per proposal has to be earned back in minutes. Aurora Basic's cost per proposal divided by $35, times 60, gives the minutes it must save per proposal.
| Minutes saved per proposal to cover the fee | 5 a month | 10 a month | 20 a month | 40 a month |
|---|---|---|---|---|
| Aurora Basic ($135) | 46 | 23 | 12 | 6 |
| Aurora Premium ($220) | 75 | 38 | 19 | 9 |
Read it as a challenge to the vendor. At ten proposals a month, Basic has to cut 23 minutes from each one compared with OpenSolar, which is hard to believe when both tools claim to lay out a system in seconds. At forty a month the bar falls to six minutes, which a better roof model or fewer revisions could plausibly clear. The figures also move with your hourly cost. At $50 an hour every number in the table falls by 30%, because each minute saved is worth more; at $25 an hour they rise by 40%.
There is a second way to justify the fee, and it has nothing to do with minutes. Suppose a signed residential system leaves you $2,500 of margin; that figure is an illustration, so use your own. Aurora Basic costs $1,620 a year, which is 0.65 of one signed job. Premium at $2,640 is 1.06 jobs. If a tool's branded proposals, financing options or shade reports win you one extra job a year that you would not have won, the fee is covered. Nobody can promise that, which is why the three-job trial at the end exists.
Where manual design stops being the cheapest
Manual design wins only at very low volume. Set Basic's $135 against the $32.08 saved per proposal ($52.50 minus $20.42), and the break-even is 4.2 proposals a month. At four proposals manual costs $210 and Basic costs $216.67, so manual is $6.67 cheaper. At five, manual is $262.50 against $237.08, and Basic is $25.42 cheaper. Premium needs 6.9, so seven: at six proposals manual is $315.00 against $342.50, while at seven it is $367.50 against $362.92.
Those margins are thin at the crossover, which is the point. A solo installer quoting four or five systems a month can reasonably stay manual while testing a free tool, since the cost of getting it wrong in either direction is a few dollars. The cost grows past ten a month, where manual design is $525 a month against $204 for the same work in OpenSolar. A manual process also has a second cost the table does not show: revisions. Changing a panel count in a spreadsheet and redoing the layout drawing takes longer than moving panels in a 3D model, and the customer who asks for a battery or a second quote makes the gap wider.
If the proposal is the front of your sales process, two companion tutorials cover the layers around it: adding AI-written cover letters and FAQs to solar proposals and explaining battery options without promising backup.
Which AI sits on which Aurora plan, and what OpenSolar adds
The "AI" in the title is where the vendors differ most from their marketing. Aurora's feature matrix lists its AI under two names, AutoDesigner for panel layout and Aurora AI for roof models and obstruction detection, and only AutoDesigner sits on the cheaper plans.
| Capability | Aurora Basic | Aurora Premium | Aurora Enterprise | OpenSolar |
|---|---|---|---|---|
| Automated panel placement, stringing and fire pathways (AutoDesigner) | Yes | Yes | Yes | Auto Design (Ada), labelled beta; an admin switches it on; no separate price shown |
| AI-assisted site models and obstruction detection (Aurora AI) | No | No | Yes | Not matched by name on its pages; check roof-model coverage for your area |
| Expert-built site models | Standard, from $9.99 | Standard, from $9.99 | Standard, from $9.99 | Not listed |
| LIDAR-assisted modelling, bankable shade reports, battery modelling | No | Yes | Yes | Auto Design page claims auto-generated, bankable shading values |
Two readings follow. First, the headline Aurora claim of 3D roof models in under 15 seconds belongs to Aurora AI, which the matrix lists on Enterprise only, so a small installer on Basic or Premium models the roof by hand or pays for an expert model. Second, the comparison for small installers is really AutoDesigner against Ada: both lay out panels automatically, one inside a paid plan and one inside a free beta feature. Treat both makers' speed claims as claims. They describe the tool's best case, not your roofs with chimneys, dormers and a neighbour's oak tree. The same goes for OpenSolar's "bankable" shading values: a beta feature's label is not your finance partner's acceptance, so ask the partner before you skip a paid shade report. E-signature differs too. OpenSolar lists it in its Sell menu, and Aurora's page lists a Contract Manager without making clear which tier carries it, so ask Aurora before counting it in a Basic or Premium price.
Expert models deserve a sum of their own. A standard Aurora on-demand model is listed from $9.99, with delivery in three hours or less; an expedited one, in 30 minutes or less, is a separate add-on. If modelling a roof yourself takes 20 minutes at $35 an hour, that is $11.67 of time, so the paid model is cheaper whenever your own modelling would take more than about 17 minutes ($9.99 divided by $35, times 60). It is worth buying for awkward roofs and not for simple gables, and the three-job trial will show which yours are.
Seats, caps and extras that change the per-proposal figure
The table above assumes one designer, one tool and nothing else. Real firms break each of those assumptions, and each break shifts the answer.
Seats come first. Aurora prices per user, and Basic and Premium each include one. If the owner, a designer and a salesperson all need to open designs, the bill is three seats. OpenSolar's pages I read state no per-seat fee, though its Teams features mention roles and permissions, so confirm user limits in your account. Projects come second. Aurora's Terms of Use give each user a monthly allowance of 50 projects and define a project as an address you start a proposal, site model or design for. Creating a project and copying one both count, so a re-quote uses a slot. Annual subscribers can roll unused projects into later months within the year; monthly subscribers cannot; and Aurora may suspend an account that goes over the allowance month after month. That is generous for a small firm, but not for a busy season.
Imagery is third. Aurora includes Google HD and Vexcel imagery and lists Nearmap as an add-on. OpenSolar says to start with free imagery and buy premium imagery per image through its Imagery Marketplace only when a job needs it; it shows the price and your Wallet balance before you confirm, and availability depends on your location. Connections come last. Accounting at $49 a month adds $2.45 to each proposal at 20 a month and $4.90 at ten. Once switched on, API access runs free for 30 days and is then billed as a fee each time a project is created, deducted from your OpenSolar Wallet at a price that varies by region, so every proposal carries it. Add the line to your own table once you know the figure. Support is the last optional line: OpenSolar's Support package is $500 a month, and the next one up, which adds branded proposal templates, is $1,350; only a busy firm wanting hands-on onboarding or its own templates would weigh either. At 20 proposals a month, Support alone adds $25 to each one, more than Aurora Basic's software cost per proposal at that volume.
Permit drawings sit outside both tools' basic price. Aurora sells plan sets and engineering stamps as add-ons, with plan sets delivered in under 24 hours (48 for solar-plus-storage) and stamps adding a day. Neither tool replaces the site survey or the person who checks the roof structure and electrical design; what AI design software does and does not do covers that boundary, and a survey checklist with photos sorted by AI covers the visit that feeds it.
Three installers, three different answers
A two-person crew quotes six systems a month and the owner designs them all. Manual design costs 6 × $52.50 = $315. OpenSolar costs 6 × $20.42 = $122.50. Aurora Basic costs $135 + $122.50 = $257.50, or $42.92 a proposal, which is barely better than doing it by hand. The answer for this crew is a free tool, or manual design while they decide, and the fee buys nothing they have shown a need for.
A five-person firm quotes 25 systems a month, and the owner, the designer and one sales rep all open designs. In Aurora that is three seats at $135, which is $405 a month or $16.20 a proposal before time, against $5.40 for a single seat. All-in, three Basic seats come to $36.62 a proposal against $20.42 for OpenSolar. The firm should ask whether the rep needs the design view at all. If not, one seat and a PDF handover brings the figure back to $25.82. This is where a free tool with no seat charge looks strongest, but the firm should still run the trial: a rep who can adjust panels live in front of a customer may close more.
A third installer quotes 45 systems a month, mostly with batteries, and the finance partner asks for bankable shade reports. Premium at $220 is $4.89 a proposal, $25.31 all-in. The 50-project cap is the risk: a 55-proposal month would need a second licence, which doubles the fee to about $8 a proposal. For this firm the paid tool has a concrete reason to exist, since the report is a requirement and not a nicety. The check is to ask the finance partner in writing whether a free tool's shading output would be accepted.
Why free has limits: what OpenSolar charges for in 2026
OpenSolar's own statement is that the core app stays free and that it earns money from hardware and finance partners. That model has a consequence worth testing. A tool paid for by hardware and finance partners is likely to put their products in front of you, so price one proposal twice, once with the default hardware and finance options and once with your own, and see whether the numbers differ. Its pages say the extras are optional, and that is checkable in an afternoon.
The 2026 announcement is the second thing to read. An OpenSolar post from June 2022 says the platform will always be free, and in 2026 two connected services became paid. The core app is still free, as the company says, but the episode shows that "free" covers what OpenSolar says it covers and not everything an installer might later want. Plan for it: if a CRM link is on your roadmap, price the per-project fee and the $49 accounting connector now, and keep PDF copies of proposals and design exports outside the platform. Any tool, free or paid, can change its terms, and supplier risk is easier to manage when your records live in your own folders.
Time three past jobs in each tool before you pay
The time assumptions drive every table above, and the only reliable source for them is a trial on your own jobs. Pick three finished jobs: a simple roof, a shaded or multi-pitch roof, and one with a battery. You already know the as-built system size and, if you have a few months of data, the actual production. Design each job from scratch in each tool and manual, with a timer running from opening the address to a customer-ready proposal. Use OpenSolar's free account for its side of the test. For Aurora, the cheapest honest test is one month of Basic on monthly billing at $159, since monthly plans carry no minimum commitment, and that is better than committing to a year before the numbers are in.
Job Tool Minutes System size vs as-built Needed a site-visit fix?
Simple gable Manual 85 -2% No
Simple gable OpenSolar 30 +1% No
Simple gable Aurora 28 0% No
Shaded roof Manual 110 -9% Yes (shade)
Shaded roof OpenSolar 45 -3% No
Shaded roof Aurora 40 -2% No
Battery job Manual 120 n/a Yes (sizing)
Battery job OpenSolar 50 n/a No
Battery job Aurora 42 n/a NoThat sheet is invented to show the layout; fill yours with real minutes. Then apply the rule from earlier. In this made-up result Aurora saved only a few minutes per job over OpenSolar, so at ten proposals a month it would need to save 23 minutes to justify Basic and fails by a wide margin. Had Aurora saved 25 minutes on every shaded roof, it would clear the 23-minute bar for a firm whose proposals are mostly shaded roofs, and the decision would turn on how many of your jobs look like that one. Run the numbers per job type, not on an average, because a firm that does mostly simple gables and a firm with mostly shaded roofs buy different things.
- Keep the same imagery source and the same panel and inverter choice across all three tools, so you test design effort and not catalogue differences.
- Record two timings: the first design, and a revision after the "customer" asks for a battery or four fewer panels. Revisions are where manual design loses most.
- Compare each result with the as-built size and, where you can, real production, and note any job that would have needed a site-visit correction.
- Put the minutes into the formula: all-in cost = subscription divided by proposals, plus minutes divided by 60 times your hourly cost.
- Check the extras you would actually use, such as a CRM link, imagery or a second seat, and add their prices to the same line.
For a wider view of where design sits in the rest of a small installer's software, solar installer software across CRM, design and tracking compares the layers, so that a cheap design tool does not leave you paying for three disconnected ones.
Questions installers ask about cost per proposal
Does Aurora's 50-project cap count proposals I lose?
Yes. Aurora's Terms of Use count every project you start, defined as a location or address for which you begin a design or sales proposal, whether you click Create Project or Copy Project. A lost quote and a re-quote therefore both use a slot. Count every design you start, not only those you win.
Is OpenSolar still free after the 2026 changes?
For the core app, yes. OpenSolar's post of 16 February 2026 says the core app stays free for work inside the platform. Since 16 April 2026 it charges for API access, billed as a fee each time a project is created, and for its own connectors, with accounting connectors listed at $49 a month. Premium imagery and support packages from $500 a month are optional extras.
When is manual design still the right choice?
When you quote fewer than about five proposals a month and a free tool would still need learning time, manual design costs little more. It also suits roofs the imagery cannot model, where you would measure by hand anyway. Above five a month, on the time assumptions used here, a tool pays for itself.
Do I need Aurora Premium for bankable shade reports?
Aurora's page lists bankable shade reports, LIDAR-assisted modelling and battery storage modelling on Premium and above, not on Basic. Premium costs $85 a month more on annual billing ($100 more monthly). Ask your finance partner whether they actually require a bankable report before paying the difference.
Further reads
- Solar Lead Generation: Cost per Lead, Cost per Survey and AI Follow-Up — Cost per lead and survey, so you can weigh proposal cost against it.
- Heat Pump Installer Software: Surveys, Heat Loss and Quotes, AI Compared — What a heat pump installer's software must do at survey, heat loss and quote stage, which tools cover which job, where AI helps and what vendors charge.
- AI Tools and AI Development: The Complete 2026 Guide — the AI hub, including every tutorial in the AI-for-business series.
Sources: Aurora Solar pricing page, Expert Design and Aurora AI pages and Terms of Use (Credits); OpenSolar 'Why is OpenSolar Free?', February 2026 pricing-change post, API page, Accounting Connectors help article, Imagery Marketplace, Auto Design and Enterprise Services pages. All read on 29 October 2026.