This article was developed by Ana Marques, working with UK solar installers across different sizes and business models. The question she gets asked most frequently isn't "how do I generate more solar leads?" It's a more fundamental one: "how many do I actually need?" As Ana puts it, "most installers I speak to have a vague sense that they need more leads. Very few have sat down and calculated the exact number that makes their business profitable. That calculation changes everything about how you buy and how you invest."
The answer depends on four variables: average installation revenue, gross margin per job, fixed monthly costs, and solar lead conversion rate. Get those four numbers right and the minimum viable solar lead volume for your business becomes a precise figure, not a guess. This article builds that calculation from first principles, applies it to three realistic UK installer profiles, and shows you where most solar companies go wrong when they try to grow without understanding their own break-even arithmetic.
The Baseline: What a UK Solar Installation Actually Earns in 2026
Before calculating how many solar leads you need, you need accurate revenue and margin figures for your typical installation. Industry data for UK solar installers in 2026 shows a wide range depending on system type, region, and business model. Still, the benchmarks below represent realistic figures for a competent residential installer.
| Installation Type | Average Revenue (£) | Typical Gross Margin | Gross Profit per Job (£) |
|---|---|---|---|
| Solar panels only (3–5kWp) | £6,500–£8,500 | 25–35% | £1,625–£2,975 |
| Solar + battery (4kWp + 10kWh) | £11,000–£15,500 | 25–32% | £2,750–£4,960 |
| Solar + battery + EV charger | £13,500–£18,000 | 26–33% | £3,510–£5,940 |
| Battery retrofit (existing solar) | £4,500–£7,000 | 28–38% | £1,260–£2,660 |
Gross margin figures of 25–35% are consistent with SurgePV's 2026 benchmark analysis of residential solar installers. Net margin, after fixed overhead, staff costs, marketing, and operational expenses, typically lands between 8–15% for well-run residential solar companies. Installers achieving net margins above 15% are either running very lean operations, installing predominantly solar-plus-battery at scale, or both.
The Break-Even Formula Every Installer Needs
The calculation that determines your minimum viable solar lead volume has three steps.
Step 1: Calculate your monthly fixed cost base. This includes salaries (office and management, not installers who are a variable cost), premises, insurance, software, vehicle leasing, and any fixed marketing retainers. For a small UK solar installer with 3 to 5 staff, this typically runs £15,000 to £35,000 per month. For a mid-sized company with 10 to 20 staff, expect £40,000 to £80,000.
Step 2: Calculate your contribution per installation. This is your gross profit per job minus the variable costs directly associated with that installation: installer labour, survey cost, and the cost of the solar lead itself. If your average job generates £2,200 gross profit, your installer team costs £600 per job, your survey costs £80, and your solar lead cost per acquisition is £300, your contribution per installation is £1,220.
Step 3: Divide fixed costs by contribution per installation. If your fixed cost base is £24,400 per month and your contribution per installation is £1,220, you need exactly 20 installations per month to break even. Every installation above 20 is net profit.
Now work backwards from installations to solar leads. At a 10% solar lead conversion rate, 20 installations require 200 solar leads per month. At 6%, you need 334. At 14%, you need 143. Your conversion rate is the single biggest lever on how many solar leads your break-even requires.
Three Installer Profiles: How Many Solar Leads Each Needs
| Installer Profile | Monthly Fixed Costs | Avg Revenue per Job | Gross Margin | Lead CPA | Contribution/Job | Break-Even Installs | Solar Leads Needed (at 10% conv.) |
|---|---|---|---|---|---|---|---|
| Small (2 installers, 1 sales) | £18,000 | £7,500 | 28% | £280 | £1,420 | 13 jobs/month | 130 solar leads/month |
| Mid-size (5 installers, 2–3 sales) | £42,000 | £9,500 | 30% | £300 | £2,050 | 21 jobs/month | 210 solar leads/month |
| Growth (10+ installers, dedicated sales team) | £85,000 | £12,000 | 31% | £260 | £2,860 | 30 jobs/month | 300 solar leads/month |
"What strikes me when I go through this exercise with installers is that most have been buying solar leads based on budget rather than based on a calculated need," Ana observes. "They spend what they can afford that month, not what the maths says they must spend to break even. Those are very different numbers, and they lead to very different outcomes."
Why Conversion Rate Is the Variable That Changes Everything
The break-even solar lead volumes above assume a 10% conversion rate, which is realistic for exclusive solar leads from well-run campaigns with fast follow-up. But conversion rate is the variable most installers underestimate and undertrack. The table below shows how dramatically your required solar lead volume shifts with conversion rate, using the mid-size installer profile (21 installations needed per month).
| Conversion Rate | Solar Leads Needed to Break Even | Monthly Lead Spend (at £28 CPL) | Lead Spend vs Fixed Costs |
|---|---|---|---|
| 5% | 420 solar leads | £11,760 | 28% of fixed costs |
| 8% | 263 solar leads | £7,364 | 18% of fixed costs |
| 10% | 210 solar leads | £5,880 | 14% of fixed costs |
| 12% | 175 solar leads | £4,900 | 12% of fixed costs |
| 14% | 150 solar leads | £4,200 | 10% of fixed costs |
The difference between a 5% and a 14% conversion rate on the same solar leads is the difference between spending £11,760 per month on leads and spending £4,200, to achieve the same 21 installations. Improving your conversion rate from 5% to 14% is worth £7,560 in monthly savings, without changing a single thing about your campaigns. That saving comes entirely from fixing follow-up speed, sales process, and lead quality. It is the highest-ROI improvement available to most UK solar installers and the one most consistently ignored in favour of buying more solar leads.
The Hidden Cost Most Installers Forget: Wasted Lead Spend
The break-even calculation above treats lead spend as a clean variable cost tied to installations. In reality, a portion of every solar lead budget is structurally wasted on leads that will never convert regardless of sales effort: invalid phone numbers, non-homeowners who slipped through qualification, prospects who had already purchased from a competitor before being contacted, and homeowners whose property is genuinely unsuitable. This wasted portion reduces your effective conversion rate and inflates your true cost per acquisition.
For shared solar leads from broad campaigns, wasted lead proportion typically runs 20 to 35%. For exclusive solar leads from well-qualified campaigns, it runs 8 to 15%. A company buying 300 shared solar leads per month at £9 each with 25% waste is effectively paying for 225 viable leads at £12 each, not 300 leads at £9. The advertised CPL is misleading unless you account for the waste rate.
"I always ask new clients to pull their CRM and show me what happened to every lead from the last 90 days," says Ana. "Usually, 20 to 30% of leads are sitting in a grey zone, no clear disposition, never properly worked, just accumulated. That's money that was spent and never given a fair chance to convert. Before we talk about buying more solar leads, we talk about recovering the value from the ones they've already paid for."
Solar Leads vs Solar Leads: Exclusive vs Shared Economics
The profitability calculation changes materially depending on whether you're buying exclusive or shared solar leads. The CPL difference is significant (£25 to £35 exclusive versus £8 to £14 shared), but the conversion rate difference reverses much of that advantage for shared leads.
Using the small installer profile (needing 13 installations per month) as a reference:
Buying exclusive solar leads at £28 CPL with 10% conversion: 130 leads needed, £3,640 lead spend, £280 CPA. 13 installations generate £97,500 revenue. Lead spend represents 3.7% of revenue.
Buying shared solar leads at £9 CPL with 4% conversion: 325 leads needed, £2,925 lead spend, £225 CPA. 13 installations generate £97,500 revenue. Lead spend represents 3.0% of revenue.
On pure CPA, shared leads look fractionally better (£225 versus £280). But shared leads require 195 more lead contacts per month from your sales team. At 5 minutes per contact attempt with 3 attempts per lead, that's an additional 48.75 hours of sales time per month, roughly one full-time sales employee's productive hours. When you include the cost of the sales time required to work shared solar leads to the same number of installations, exclusive leads are almost always cheaper per installation for installers with established sales teams.
Battery Attachment Rate: The Profit Multiplier You Control
One of the fastest ways to reduce the number of solar leads you need to hit your profit target is increasing your battery attachment rate, the proportion of solar installations that also include a battery system. The economics are straightforward.
A panels-only installation at £7,500 with 28% gross margin generates £2,100 gross profit. The same customer installing solar-plus-battery at £13,000 with 30% gross margin generates £3,900. The same solar lead, the same survey, the same sales effort, generates 86% more gross profit when battery is included.
If your current battery attachment rate is 15% and you raise it to 35%, your average gross profit per installation increases by approximately £270. For an installer doing 20 jobs a month, that's an additional £5,400 in monthly gross profit from the same solar lead volume. Across 12 months, that's £64,800 in additional gross profit without acquiring a single additional solar lead.
"Battery attachment is where I see the biggest missed opportunity for most installers," Ana notes. "They're generating the solar lead, they're running the survey, they've built the relationship with the homeowner, and then they present a panels-only quote because that's what the homeowner originally asked about. A well-trained surveyor presenting battery economics on every qualifying job can shift attachment rate from 15% to 35% in two months. That improvement is worth more than doubling your solar lead budget."
Building Your Own Break-Even Model
The framework below lets you calculate your own minimum viable solar lead volume in under ten minutes.
Your monthly fixed costs (£): Add all non-variable monthly outgoings. Salaries of non-installation staff, premises, insurance, software, vehicle leasing, fixed marketing costs.
Your average gross profit per installation (£): Average installation revenue multiplied by your gross margin percentage.
Your average variable cost per installation (£): Installation labour per job, survey cost, and your solar lead cost per acquisition (CPL divided by conversion rate).
Your contribution per installation (£): Gross profit minus variable cost per installation.
Your break-even installations per month: Fixed costs divided by contribution per installation.
Your minimum viable solar lead volume: Break-even installations divided by your conversion rate.
Run this calculation with your actual numbers, then run it again with a 14% conversion rate (achievable with exclusive leads and fast follow-up) and with a 35% battery attachment rate. The difference between your current numbers and the optimised scenario is the opportunity sitting in your existing operation before you spend an additional pound on solar leads.
The Number That Should Drive Every Solar Leads Decision
Every decision about how many solar leads to buy, which type to buy, and from which provider should flow from your break-even calculation. Buying solar leads without knowing your break-even lead volume is the equivalent of filling a car with petrol without knowing how far you need to travel. You might have enough. You might run dry two miles from the destination. You have no way of knowing.
UK solar installers in 2026 operate in the best demand environment in a decade. Electricity prices remain high, battery storage has become mainstream, and the Future Homes Standard has permanently legitimised solar in the public conversation. The installers who will capture disproportionate value from this environment are not necessarily those buying the most solar leads. They're the ones who know exactly how many solar leads they need, at what conversion rate, with what battery attachment, to hit their profit targets, and who invest accordingly.
"The calculation takes 20 minutes," Ana concludes. "But it changes how you think about every pound you spend on solar leads. It turns a gut-feel budget decision into a business case. And once you've done it, you can't unsee how much money is left on the table by companies that haven't."
Want help building your break-even solar leads model and designing a campaign to hit it? ImperioLeads works with UK solar installers to calculate the exact lead volume, quality, and budget their operation needs to grow profitably.
