Solar Installer ROI Calculator: Are Your Leads Worth It?

Most solar installers track leads and installs but don't have a rigorous framework for evaluating whether their marketing spend is actually profitable at the margin. This guide gives you the exact formulas, benchmarks, and calculations to determine whether any given lead source is worth continuing — and at what scale.

The Core ROI Framework

There are three numbers every solar installer needs to know cold:

1. Gross Profit Per Install (GPPI): Revenue minus direct costs (panels, inverter, hardware, labor, permits, interconnection)
2. True Cost Per Install (TCPI): Marketing spend divided by actual completed installs (not signed contracts, not leads)
3. Marketing ROI: (GPPI − TCPI) ÷ TCPI

Step 1: Calculate Your Gross Profit Per Install

For a typical residential system in 2026:

Component	Small System (6 kW)	Average System (9 kW)	Large System (13 kW)
Gross revenue (contract value)	$19,800	$29,700	$42,900
Panels + hardware	−$6,500	−$9,800	−$14,200
Inverter(s)	−$1,200	−$1,800	−$2,500
Install labor	−$2,400	−$3,200	−$4,200
Permits and inspections	−$800	−$1,000	−$1,400
Interconnection fee	−$200	−$200	−$300
Design/engineering	−$400	−$500	−$700
Gross Profit	$8,300	$13,200	$19,600
Gross Margin	42%	44%	46%

These are direct costs only. Overhead — sales commissions, office rent, vehicles, insurance, software — comes out of gross profit. A company running a 15% overhead expense ratio nets 27–31% EBITDA margin before marketing spend on average residential solar.

Step 2: Calculate Your True Cost Per Install

This requires tracking from lead to completed install, including cancellations:

Example: You spend $15,000 on Google Ads in Q1, generating 80 leads. Of those, 55 are qualified, 28 book appointments, 22 show up, 7 sign contracts, 1 cancels before install. You complete 6 installs from this campaign (lag-adjusted). Your TCPI from Google Ads is $15,000 ÷ 6 = $2,500 per install.

The "lag-adjusted" note is important: solar has a 30–120 day cycle from lead to install. Installs completed in Q1 were likely generated from Q4 leads. Match your cost to the leads that ultimately drove those installs, not the leads generated in the same quarter.

Step 3: Calculate Channel ROI

Using an average system GPPI of $13,200 and a TCPI of $2,500:

A 428% ROI on marketing spend means for every $1 you put into lead generation, you get back $5.28 in gross profit. That's before overhead and sales commissions, but it's a strong return that fully justifies continued investment.

Benchmark ROI by Channel

Channel	Typical TCPI (CA)	GPPI ($13,200 avg)	Marketing ROI	Assessment
Referrals	$250–$800	$13,200	1,550–5,180%	Excellent
Organic SEO	$300–$900	$13,200	1,367–4,300%	Excellent
AI direct mail	$600–$2,000	$13,200	560–2,100%	Very Good
Google Search Ads	$1,500–$4,000	$13,200	230–780%	Good
Facebook/Meta Ads	$1,200–$4,500	$13,200	193–1,000%	Good–Variable
Canvassing	$2,000–$8,000	$13,200	65–560%	Variable
Purchased shared leads	$3,500–$25,000	$13,200	-47–277%	Often Negative

Customer Lifetime Value: Why LTV Changes the ROI Calculation

The ROI calculations above account only for the first installation. A solar customer who has a great experience has lifetime value that extends well beyond the initial contract:

• Battery storage add-on: 20–35% of solar customers add battery storage within 3 years of installation. At $3,000–$6,000 gross profit per battery install, this adds significant LTV.
• Service and maintenance contracts: $150–$300/year for monitoring and annual inspection. On 200 active customers, that's $30,000–$60,000/year in recurring service revenue.
• Referrals: At a 20% referral rate, each customer generates 0.2 additional customers. If your average customer refers 0.2 people, and those refer 0.2, your effective LTV multiplier is 1.25x (1 ÷ (1−0.2)).
• Panel upgrades: As panel technology improves, some customers upgrade to higher-efficiency panels in year 8–12. An upgrade project generates $4,000–$8,000 in gross profit at very low acquisition cost.

A fully loaded LTV calculation including referrals and service revenue might show $18,000–$22,000 per customer versus the $13,200 first-install GPPI alone. This expands the acceptable maximum TCPI and justifies investment in higher-cost channels that deliver better quality customers.

Maximum Allowable CPI by Margin Target

What's the maximum you should pay per install, by target net margin?

Target Net Margin After Marketing	GPPI $10,000	GPPI $13,200	GPPI $18,000
30% net margin	$7,000 max TCPI	$9,240 max	$12,600 max
20% net margin	$8,000 max TCPI	$10,560 max	$14,400 max
10% net margin	$9,000 max TCPI	$11,880 max	$16,200 max

These limits include all sales commissions, marketing spend, and fully loaded acquisition costs. Most well-run solar installers target 20–30% net margin after all selling costs, implying a maximum TCPI of $9,000–$10,500 on an average $13,200 GPPI system.