solar
Do solar panels work less in Malta's summer heat?
Yes, in a specific sense. A panel is rated at a cell temperature of 25C and output falls as the cell runs hotter. Maltese summer roofs run well above that, so the hottest month is not automatically the best producing month. The thing you can control is mounting: a frame with airflow behind the panels runs cooler.
Malta has a lot of sun. That is the reason to fit PV here. It is also the reason a lot of Maltese systems give back less than the number printed on the box, because that number is measured in a laboratory at a cell temperature most Maltese roofs leave behind well before noon in July.
Do solar panels work less in Malta’s summer heat?
Yes, in one specific sense. A panel’s rated output is measured at a cell temperature of 25C. As the cell runs hotter than that, voltage falls and power output falls with it. Malta’s summer delivers the most sunlight and the hottest panels at the same time, so the two effects pull against each other.
The panel is not broken and nothing needs adjusting. It is a physical property of silicon, and it is on the datasheet of every module ever made.
What is actually happening inside the panel when it heats up?
Sunlight knocks electrons loose in a silicon cell. Heat raises the baseline energy of those electrons, which reduces the voltage the cell can hold across its terminals. Current rises very slightly, voltage falls more, and net power drops. Manufacturers publish this as a temperature coefficient of power.
That coefficient is a negative number, expressed as a change in power for every degree C above 25C. It is different for every module. A cheaper module usually has a worse one, and it is one of the few genuinely comparable numbers between two quotes. We are not going to print a typical value here, because the useful figure is the one on the datasheet of the module you are actually being sold.
Does that mean July is not the best production month in Malta?
We have not verified monthly output figures for Malta, and we will not publish one until we have. What we can say is the mechanism: irradiance and day length push summer output up, cell temperature pulls it down. The hottest month is therefore not automatically the highest producing month.
This matters when someone shows you a projection. If a quote gives you annual output only, ask for it broken down by month, and ask whether the model applies a temperature correction or just multiplies sunshine hours by rated capacity. The second approach flatters summer and is meaningless.
Why does a flat unventilated mount run hotter than a raised one?
A panel sheds heat three ways: conduction into whatever it touches, radiation, and air moving across its back face. Airflow behind the module is the main route. Lay a panel flat against a hot roof deck, or box it in behind a parapet, and that route closes. The cell sits hotter for longer and gives back less.
Maltese roofs make this worse than most. Flat concrete roofs absorb heat all day and re-radiate it upward into the back of the panel through the evening. Parapet walls, water tanks, washing lines, roof rooms and air conditioning condensers all block the breeze that would otherwise carry heat away. A roof that looks unobstructed for shading can still be dead air.
The tilted frame that installers propose for angle reasons is also doing thermal work. That is worth knowing before you accept a cheaper flush mount to save a few hundred euro.
What should you ask an installer about mounting clearance?
Ask for the air gap in millimetres between the back of the module and the roof surface, in writing on the quote. Then ask what is upwind of the array, and whether the frame is ventilated at the sides or closed in. Get the module’s temperature coefficient of power from the datasheet, not from memory.
| What to ask | Why it matters | A weak answer |
|---|---|---|
| What is the clearance behind the modules, in mm? | Airflow is the main cooling route | “Standard mounting” |
| Is the array boxed in at the sides or open? | Closed frames trap hot air | “It will be fine” |
| What blocks the breeze on this roof? | Parapets and tanks create dead air | No site visit was done |
| What is the module’s temperature coefficient of power? | Directly comparable between quotes | “All panels are the same” |
| Is modelled output temperature corrected? | Uncorrected models overstate summer | Annual figure only, no method |
How does the 2026 grant interact with any of this?
It does not. The RES grant is calculated on eligible cost and system size, never on generation. Two identical 5 kWp systems, one well ventilated and one flush against a hot roof, receive exactly the same grant. Heat does not change what you are paid. It changes what you get back afterwards.
| Item | Rule | Cap |
|---|---|---|
| PV with hybrid inverter | 65% of eligible cost | €3,000 per system and €645 per kWp, whichever binds first |
| Battery storage | 75% of eligible battery cost | €6,000 per system and €600 per kWh, only bundled with new PV plus hybrid inverter |
| Maximum combined household grant | 3,000 plus 6,000 | €9,000 (derived by us, not printed by REWS) |
| VAT on residential solar in Malta | 18% standard rate, no reduced rate exists | Included in eligible cost |
| Cap crossover point | 3,000 divided by 645 | 4.651 kWp |
That last row is the one nobody publishes. Below 4.651 kWp the per-kWp cap binds. Above it the flat €3,000 binds. Worked through on a 5 kWp system:
| Step | Figure |
|---|---|
| System size | 5 kWp |
| Eligible cost, VAT inclusive | €6,250 (illustrative example, not a market price) |
| 65% of eligible cost | €4,062.50 |
| Per-kWp cap, 5 x 645 | €3,225 |
| Per-system cap | €3,000 |
| Grant paid, lowest binds | €3,000 |
| You pay | €3,250 |
Eligible cost is reduced by discounts or offers (cash or in kind), by any extended warranty beyond the standard 10 year warranty, and by import duty on overseas purchases. You must not also claim a tax rebate, deduction or input VAT credit on the same expenditure.
What does this change about how you compare two quotes?
Stop comparing on kWp alone. Two 5 kWp systems on the same roof can give back materially different amounts over twenty years depending on module coefficient and mounting clearance, while costing you the same after grant. Compare modelled annual output, the correction method behind it, the coefficient, and the air gap.
If an installer will not put the clearance figure on the quote, that tells you something on its own.
A note on sequencing, because it costs people money. Part A must be submitted before purchase and installation, and REWS advises applicants not to enter a binding contract or pay anything, including a deposit, before receiving a grant offer letter. Processing is generally about 5 weeks for a complete application, and the offer is valid 8 months covering installation, commissioning and Part B.
Dawl does not install anything. We publish the arithmetic, including when the arithmetic says wait or say no, and we refer enquiries to one installer who pays for them. Feed-in tariff rates are being verified against the statutory instrument and this page will be updated when that is done. Until then we are not printing a payback period, because a payback figure without a verified tariff is a guess with a decimal point on it.
Questions
- Do solar panels stop working when it gets very hot in Malta?
- No. They keep generating. What changes is how much power you get per rated watt. Above a cell temperature of 25C, output per watt falls, and it recovers as the panel cools. Nothing is damaged and nothing needs resetting. It is a continuous effect, not a cut-off.
- Is a raised mounting frame covered by the 2026 grant?
- Yes. REWS lists the support frame inside eligible cost, alongside PV modules, inverters, battery storage equipment, interface modules, other materials and works, and certification. Eligible cost is VAT inclusive. So paying for a properly ventilated frame does not sit outside the grant calculation, it forms part of it.
- Does a hotter roof mean I get a smaller grant?
- No. The PV grant is 65% of eligible cost, capped at €3,000 per system and €645 per kWp, whichever binds first. It is calculated on money spent and system size, never on generation. A hot system and a cool system of the same size and cost receive the same grant.
- Should I wait until autumn to install so the panels start in cooler weather?
- Waiting does not change lifetime output in any way worth planning around, and the grant timetable matters more. Part A must be submitted before purchase and installation. REWS states no processing period is fixed at law, generally about 5 weeks for a complete application. The grant offer is then valid 8 months.
- Will adding a battery offset the summer heat losses?
- No. A battery stores what the panels produce, it does not increase production. Under the 2026 scheme battery storage is only available bundled with a new PV system plus hybrid inverter. Since 13 July 2026 REWS has stopped accepting Part A applications for standalone battery and hybrid inverter retrofits.
- How much output do Maltese panels lose in summer, as a percentage?
- We have not verified a figure and will not publish one. The loss depends on the specific module's temperature coefficient, the cell temperature it actually reaches, and the mounting. Ask your installer for the coefficient from the datasheet and for modelled monthly output for your roof, in writing.
Sources
We publish the working. We do not install anything. How this works