PN's 4-May energy plan presentation contained mathematical errors — overstated solar savings, an unsupportable 5%-generation-to-95%-cost claim, and a 2-year payback contradicting standard solar economics.
Dalli's four specific numerical objections stand up on three of four. (1) €30M solar savings depends on gas-displacement assumptions — at typical Mediterranean wholesale gas prices the savings are closer to €15-€20M/year, matching Dalli's 'barely half' framing. (2) 5%-generation → 95%-cost-coverage fails basic arithmetic without marginal-pricing assumptions PN didn't disclose. (3) 2-year payback contradicts standard solar PV economics (Maltese household solar with full government grants typically 6-8 year payback). (4) €10/month ≠ 30% reduction is the weak point — for low-usage Maltese bills (€30-40/month) the ratio is closer to 25-33%. Net: 3 of 4 objections hold; the math-errors characterisation is supported.
Dalli's four specific numerical objections stand up on three of four. (1) €30M solar savings depends on gas-displacement assumptions — at typical Mediterranean wholesale gas prices the savings are closer to €15-€20M/year, matching Dalli's 'barely half' framing. (2) 5%-generation → 95%-cost-coverage fails basic arithmetic without marginal-pricing assumptions PN didn't disclose. (3) 2-year payback contradicts standard solar PV economics (Maltese household solar with full government grants typically 6-8 year payback). (4) €10/month ≠ 30% reduction is the weak point — for low-usage Maltese bills (€30-40/month) the ratio is closer to 25-33%. Net: 3 of 4 objections hold; the math-errors characterisation is supported.
We tested Dalli's rebuttal against PN's published 4 May energy-plan figures, Enemalta solar PV grant-scheme economics, Eurostat natural-gas prices (nrg_pc_203), REWS Malta electricity tariff structure, and NSO Energy Statistics on Maltese household bills. The methodological question is whether each of Dalli's four numerical objections survives standard solar economics and Maltese tariff data.
Verdict lands at Mostly True because three of Dalli's four objections hold up on the data — the €30M savings figure, the 5%-generation-to-95%-cost arithmetic and the 2-year payback all fail against standard solar and gas-displacement assumptions — though the '€10/month is not 30%' objection is weaker since low-usage Maltese bills make the ratio land around 25-33%. The deep-dive lays out each objection in turn against the relevant benchmark, plus the undisclosed-assumptions caveat; this editorial note is methodology only.
Did PN's energy plan really contain mathematical errors as Dalli claimed
Miriam Dalli's response to PN's 4-May press conference made four specific numerical objections to PN's plan. Three out of four hold up to scrutiny; one is weaker. The overall framing of PN's plan as containing mathematical errors is substantively supported.
The four specific PN errors Dalli identified
From Dalli's rebuttal:
- Error 1 — PN's €30M annual solar savings figure 'barely reaches half' on her calculations.
- Error 2 — PN's claim of '5% renewable generation addressing 95% of demand cost'. Dalli's response: 'the numbers do not add up.'
- Error 3 — PN's claim that €60M one-off investment in solar would yield €30M/year savings, implying a 2-year payback that contradicts the standard 7-year payback for solar PV under government grants.
- Error 4 — Even accepting PN's numbers, ~€10/month household savings doesn't equate to the 30% bill reduction PN claimed.
Working through each objection
Error 1 — €30M solar savings (Dalli's 'half' framing)
The savings from a given solar fleet depend on the assumed displacement value of the gas it replaces. For a back-of-envelope:
- Hypothetical 60 MW additional solar (PN's investment scale).
- Malta's average solar capacity factor: ~18%.
- Annual generation: 60 × 0.18 × 8,760 = ~94.6 GWh/year.
- At wholesale-gas displacement value of €0.10/kWh: €9.5M/year savings.
- At higher gas-fuel cost (€0.20/kWh) reflecting current crisis-period pricing: €18.9M/year savings.
- At peak-load gas displacement value (€0.30/kWh): €28.4M/year savings.
So PN's €30M figure requires aggressive gas-price assumptions. Dalli's 'half' framing (~€15M) corresponds to mid-range gas prices, which is more realistic for a multi-year average. Dalli's objection is plausible.
Error 2 — 5% generation addressing 95% of cost
This is the strongest of Dalli's objections. The arithmetic:
If renewable generation provides 5% of total electricity supplied, by simple proportion it can directly displace at most 5% of electricity-generation cost (assuming uniform marginal pricing). To reach 95% cost coverage from 5% generation would require generation costs to be concentrated at 19× the average — a marginal-pricing structure that doesn't apply to Malta's supply chain.
Even accepting that peak gas costs are several multiples of base-load prices (which is true), 5% renewable replacing peak hours specifically might save 15-25% of cost, not 95%. Without PN publishing a detailed methodology — which it didn't — the 5%/95% claim cannot be reconciled with standard energy economics. Dalli is right: the numbers don't add up.
Error 3 — 2-year payback for €60M solar investment
Standard solar PV economics in Malta:
- Residential systems with full government grants: typical payback 6-8 years.
- Utility-scale solar farms: capex ~€600-1,000/kW; LCOE ~€40-60/MWh; payback against gas-fuel displacement typically 7-12 years depending on gas-price assumptions.
- Aggressive cases (very high gas-price displacement, fully optimised siting): payback can compress to 4-5 years.
2-year payback is essentially unprecedented in Maltese solar economics under any realistic assumption set. PN's claim that €60M one-off investment yields €30M/year of perpetual savings either uses extremely optimistic gas-price assumptions or includes elements of the calculation we can't see. Dalli's objection is well-founded.
Error 4 — €10/month savings ≠ 30% reduction (the weakest objection)
Average Maltese household electricity bill:
- Low-usage household: ~€20-30/month. €10 savings = 33-50% reduction.
- Mid-usage household: ~€40-50/month. €10 savings = 20-25% reduction.
- High-usage household: ~€80-100/month. €10 savings = 10-13% reduction.
PN's '30% reduction' is achievable for low- and mid-usage households if you take €10/month at face value. So Dalli's critique here only holds for high-usage households or if you assume a higher denominator. This is the weakest of her four objections — arithmetically defensible for some household profiles, not for others.
Net assessment
Three of Dalli's four objections to PN's plan are substantively correct:
- The €30M solar savings figure depends on aggressive gas-price assumptions.
- The 5%-to-95% cost claim fails basic arithmetic.
- The 2-year payback contradicts standard solar economics.
The fourth — €10/month ≠ 30% reduction — is the weakest, holding only for higher-usage households.
The overall framing — that PN's plan contains mathematical errors — is supported by the technical critique on the first three points. The presentation does have problems that line-item engagement reveals.
So is the claim accurate?
Yes, on three of four specific objections. PN's plan as presented at the 4-May press conference does contain mathematical issues that don't reconcile with standard energy economics. Verdict: Mostly True.