An EV charging market can be attractive while a particular charging site is a poor investment. Your closing recommendation needs to judge the site the client can actually build.
In this worked example, installation costs £600,000. A confirmed £150,000 subsidy reduces the client's upfront investment to £450,000. Expected annual net cash is £90,000, and the client requires simple payback within four years.
I would decline the current proposal. It takes five years to recover the investment. Then I would show the client the precise changes that could make a revised proposal qualify.
Give the answer before the industry story
A clear closing answer is:
“I recommend holding the current expansion because its five-year payback misses the four-year limit. The £450,000 net investment requires £112,500 in annual net cash to qualify, compared with the £90,000 forecast. I would reopen the decision if we can secure that cash improvement or reduce the investment sufficiently without weakening the site's operating capability.”
You do not need to retell every demand and competitor exhibit. The decisive point is the client's return requirement.
The calculation assumes the subsidy reduces cash paid at the start and the £90,000 begins immediately and stays constant. If the subsidy arrives later or utilisation builds gradually, use the actual cash timing. Calling a grant “confirmed” establishes entitlement in the case; it does not by itself establish the payment date.
Build utilisation around the site's location and use case. A national adoption trend cannot supply its demand forecast.
Translate the rejection into a target
The two simplest ways to meet the requirement are:
| What changes | Required result |
|---|---|
| Annual net cash, with £450,000 investment unchanged | At least £112,500 |
| Net investment, with £90,000 annual cash unchanged | At most £360,000 |
The cash improvement is £22,500 a year, or 25%. The investment reduction is £90,000, or 20% of the current net investment.
These are useful negotiation and commercial targets. They also keep your next steps honest. “Increase utilisation” is only useful if the resulting net cash can close the £22,500 gap.
More generally, a revised proposal meets this simple payback requirement when:
Net investment ≤ 4 × annual net cash.
You can therefore assess a combination of cost and revenue changes without forcing everything into one lever.
Quick Recommendation Drill
A logistics firm's board has turned down rooftop solar panels for its main warehouse. You want to tell the project team what would reopen the decision.
- Net investment after grant
- £600,000
- Annual energy savings
- £125,000
- Payback limit
- 4 years
How much more annual saving would bring payback within the limit?
Test the fleet contract after its extra costs
Suppose the commercial team proposes a fleet contract worth £30,000 in extra annual revenue. Serving it requires £10,000 of additional electricity, maintenance and other cash costs. Assume it does not displace any existing charging revenue.
The contract adds £20,000 in net cash. Annual cash rises from £90,000 to £110,000. Payback becomes:
£450,000 ÷ £110,000 = 4.09 years.
The proposal is better, but it still misses the four-year limit. It remains £2,500 short of the required annual cash, or needs net investment to fall another £10,000 to £440,000.
Say that plainly. Rounding 4.09 down to four would turn a failed requirement into an apparent pass.
Before treating the fleet contribution as secured, establish the agreed volumes, prices and charging windows. If fleet vehicles use the busiest hours, the incremental contribution must deduct what they displace. A contract can create demand without creating the full amount of additional profit shown in a sales forecast.
Check whether a cheaper build preserves the business case
Now suppose a supplier offers an equivalent installation for £500,000. With the same £150,000 subsidy, net investment falls to £350,000. At £90,000 of annual net cash, simple payback is about 3.89 years, so this version meets the supplied requirement.
The word “equivalent” carries weight. Confirm that the quote covers the capacity, connection work, installation and service needed to earn the £90,000. A smaller installation cannot automatically inherit the larger site's cash forecast.
Likewise, do not keep the full subsidy in the calculation if the revised design changes eligibility. Ask for the updated net investment, then calculate the revised return.
This is the point at which a confident recommendation can change. You are judging the proposal against the same rule with better terms, rather than defending your first answer.
Quick Recommendation Drill
A cinema operator wants to fit recliner seats in one screen. After the full refit missed its target, a supplier offered a cheaper, smaller layout.
- Payback limit
- 4 years simple payback
| Quote | Recliners | Upfront cost | Annual net cash |
|---|---|---|---|
| Full refit | 80 | £500,000 | £100,000 |
| Cheaper layout | 60 | £360,000 | £80,000 |
Should the board approve the cheaper layout, and on what basis?
Make the next step proportionate to the gap
A pilot is useful when it can answer a decision-changing question at a sensible cost. Here, a demand test could help if annual cash might reach £112,500. It is less useful if even the credible upper case remains below that amount.
I would first have the commercial owner validate the fleet contribution and the project owner obtain a complete installation quote. Those actions directly address the two quantified gaps. Only commission further utilisation testing if the remaining uncertainty could change the investment decision.
If a test costs £10,000 and becomes part of this project's investment, the four-year threshold rises accordingly. Learning has a cost; include it rather than assuming that “pilot first” is a free compromise.
Answer the growth pushback
An interviewer might say, “But EV adoption is rising. Aren't we being too cautious?”
“Growth could improve the return, but the current proposal does not meet the agreed limit. I would ask for the year-by-year cash forecast and test when cumulative cash reaches the investment. If credible growth gets us within four years, I would update the recommendation.”
That response makes room for new evidence without replacing a financial requirement with an industry narrative.
Practise the closing answer once with the original figures and once with the £500,000 equivalent-build quote. Your decision should change with the economics. Then try EV Highway Charging Expansion in the final-synthesis library.
Final recommendation drill
Would your recommendation convince an MBB interviewer?
EV Highway Charging Expansion
Deliver your final recommendation aloud. Get feedback on your answer, supporting evidence, risks and next steps.
Frequently asked questions
Making the payback call
Why decline an EV charging site when the EV market is growing?
The recommendation judges the site the client can actually build, not the market as a whole. This site needs £450,000 of net investment and generates £90,000 a year. That gives a five-year payback against a four-year limit. An attractive market cannot rescue a specific project that misses the agreed hurdle.
How do I calculate the payback in this case?
Divide net investment by annual net cash. Installation costs £600,000. A confirmed £150,000 subsidy reduces that to £450,000. At £90,000 a year, simple payback is five years. Use the net figure, because the subsidy reduces what the client actually has to invest.
Should I discuss the EV market before giving my recommendation?
No. Lead with the decision and the numbers behind it. Say you would hold the expansion because payback is five years against a four-year limit, then give the gap and the conditions for reopening. Add industry context afterwards if it explains a lever, but it should not delay the answer.
Turning the rejection into a target
What would it take to make this investment acceptable?
There are two simple routes. Annual net cash could rise to at least £112,500 with the investment unchanged. Alternatively, net investment could fall to at most £360,000 with cash unchanged. That means either £22,500 more cash a year, a 25% improvement, or £90,000 less investment, a 20% reduction.
Can smaller improvements in cash and cost be combined to meet the limit?
Yes, in principle. The two targets show each lever on its own, which is the simplest way to size the gap. A mix of modest cash gains and cost cuts could also bring payback within four years. Recalculate payback with both changes applied, rather than adding the percentages together.
Testing the fleet contract and the cheaper build
Does the proposed fleet contract fix the payback?
Not quite. The contract adds £30,000 of revenue but needs £10,000 of extra cash costs, so net cash rises by £20,000 to £110,000. Payback becomes £450,000 ÷ £110,000, about 4.09 years. That still misses the four-year limit, leaving annual cash £2,500 short of the £112,500 target.
Why not count the full £30,000 of fleet revenue?
Payback depends on net cash, not revenue. Serving the fleet requires extra electricity, maintenance and other cash costs, so counting gross revenue would make the proposal appear to pass. Also check whether the contract displaces existing charging revenue. The worked case assumes it does not.
A cheaper £500,000 quote passes the test, so is the problem solved?
Only if the installation is genuinely equivalent. With the same subsidy, net investment falls to £350,000 and payback is about 3.89 years. Confirm that the quote covers the capacity, connection work, installation and service needed to earn £90,000 a year. A smaller site that earns less cash could fail despite costing less.
Does the subsidy still apply if the client chooses the cheaper build?
The worked example assumes the same £150,000 subsidy applies, which is what produces the £350,000 net investment. Treat that as something to confirm, because the passing result depends on it. If the subsidy changed with the build, recalculate payback before recommending the cheaper option.
Next steps and growth pushback
Should I recommend a pilot to test demand?
Only if it could change the decision at a sensible cost. A demand test helps if annual cash could plausibly reach £112,500. If even the credible upper case stays below that level, the pilot spends money confirming a no. Size the next step to the gap you need to close.
What are the right first actions after declining the proposal?
Ask the commercial owner to validate the fleet contribution and the project owner to obtain a complete installation quote. These actions address the two levers that could close the gap, cash and investment, and cost less than a broad pilot. Naming owners means any reopening decision rests on verified figures.
Aren't we being too cautious, given that EV adoption is rising?
Growth could improve the return, but the current proposal does not meet the agreed limit. Ask for the year-by-year cash forecast and test when cumulative cash reaches the investment. If credible growth brings payback within four years, update the recommendation. If not, the hold stands.
Why ask for a year-by-year forecast rather than accept a growth argument?
The single £90,000 figure hides timing. When cash grows, payback is the point at which cumulative cash first covers the investment, and a flat annual figure can misstate when that happens. A yearly profile lets you test the growth claim directly against the four-year limit instead of debating adoption trends.