Independent comparisons. We may earn from shop links. More info

PWM vs MPPT

Updated: October 2026

You have opened a solar panel kit, found a PWM controller in the bag, and started a PWM vs MPPT argument with the internet. The claim that MPPT is always the better circuit in Britain is only half the decision. Every kit in this [Solar panel kit comparison](/hub/electrical-equipment/solar-panel-kit) ships with PWM, from the £38.99 25 W maintainer to the £209.99 kit stated as 390 W, at the amazon.co.uk prices recorded on 19 October 2026. The question is whether that box is enough for your battery, or the part you should replace. A lead-acid battery in a dry shed is a different job from a campervan roof in a grey January.

You have opened a solar panel kit, found a PWM controller in the bag, and started a PWM vs MPPT argument with the internet. The claim that MPPT is always the better circuit in Britain is only half the decision.

Our top picks

ECO-WORTHY ECO-WORTHY 240W solar panel kit

Best overall

ECO-WORTHY ECO-WORTHY 240W solar panel kit
8.5/10about £164.49
View offer
ECO-WORTHY ECO-WORTHY 390W bifacial solar panel kit

Rank 2

ECO-WORTHY ECO-WORTHY 390W bifacial solar panel kit
7.9/10about £209.99
View offer
ECO-WORTHY ECO-WORTHY 25W 12V solar panel kit

Rank 3

ECO-WORTHY ECO-WORTHY 25W 12V solar panel kit
6.8/10about £38.99
View offer
On this page
  1. 1.What PWM does to a 12 V panel
  2. 2.When PWM is still the right box
  3. 3.When the kit's controller is the weak part
  4. 4.Swapping without a new mistake

What PWM does to a 12 V panel

A nominal 12 V panel is built so its best power sits higher than a resting battery, often in the high teens of volts, while the battery sits nearer 12 to 14 V as it charges. Victron's account is the one to use. A PWM controller pulls the array voltage down to battery voltage, so the panel never sits where its wattage is quoted. An MPPT controller finds that higher point and converts the extra voltage into current the battery can accept. Victron put the MPPT advantage at about 10% to 40% when the cells are cold, very hot, or the light is weak. The 30 W kit and the DOKIO folding 100 W kit use a 10 A PWM controller, the rigid Hoysicy 100 W a 20 A unit, and the three larger kits a 30 A unit.

When PWM is still the right box

Keep the included controller when the panel is small and the job is maintenance. The ECO-WORTHY 25 W at £38.99 and the Hoysicy 30 W at £39.99 hold a stored lead-acid battery, and the watts MPPT might recover on that panel are a handful. Azeco recommend MPPT for shade, a tight space, or cloud and cold, and they say that pattern looks like the UK. An unshaded shed may not repay the extra controller. Use the solar panel kit buying guide to check that 25 or 30 W is the watt band you need. The Hoysicy 30 W bullets name AGM, flooded and gel, not lithium. A review on that listing says the controller will not charge LiFePO4. If your leisure battery is lithium, this PWM box is the wrong profile however small the panel is.
ECO-WORTHY ECO-WORTHY 240W solar panel kit

Testsieger

ECO-WORTHY ECO-WORTHY 240W solar panel kit
8.5/10about £164.49
View offer

When the kit's controller is the weak part

Question the controller once the array is large, shaded, or buyers on the listing say they set it aside. The KOLLNIUN 240 W at £129.99, the ECO-WORTHY 240 W at £164.49 and the ECO-WORTHY 390 W bifacial at £209.99 are the kits people fit to vans. Damian Gray and another British reviewer on the 390 W listing say the supplied controller wastes a large share of the panel and that they want MPPT. The ECO-WORTHY 390 W bullets name lithium, lead-acid and gel. A KOLLNIUN review says the manual includes LiFePO4, and the Hoysicy 30 W does not. Match the job on the best solar panel kit page, or the roof on the solar panel kit for a campervan page.

Swapping without a new mistake

The replacement has to accept the panel's open-circuit voltage and the battery chemistry. One KOLLNIUN reviewer reports an input ceiling of about 23 V on the 12 V setting, and paralleled the two panels instead of series. An MPPT controller often accepts a higher array voltage and steps it down, so that series pair can become possible, though too many volts still destroys a controller. A lead-acid float on LiFePO4 is the wrong curve even if the case says MPPT.

Common questions

What is the actual difference in one sentence?
PWM ties the panel to battery voltage, so a nominal 12 V panel cannot sit where its wattage is quoted, while MPPT turns the extra voltage into charging current. Victron puts the gap at about 10% to 40% in cold, hot or dim conditions. That range is not a test of these kits.
Is PWM acceptable on a 25 W or 30 W maintainer?
Yes, if the battery is lead-acid, AGM or gel and the panel only stops a stored battery going flat. The watts MPPT might recover on 25 W are small beside a second controller. It is the wrong box if the battery is LiFePO4 and the listing, as with the Hoysicy 30 W, has no lithium profile.
Should I replace the controller on a 240 W or 390 W kit?
Treat the included PWM controller as the part most likely to limit a 240 W or 390 W kit, especially on a van in winter or in partial shade. UK reviewers of the ECO-WORTHY 390 W kit already say they want it swapped. The replacement has to name your chemistry and stay above the array's cold open-circuit voltage.
Does MPPT help in a British winter?
It helps when cells are cold and light is weak, which is the winter Azeco likens to a case for MPPT and the band where Victron says the gap grows. It will not turn a four-hour nameplate sum into a December day.
Will PWM charge a LiFePO4 battery?
Only when that controller has a lithium profile. The ECO-WORTHY 390 W listing names lithium, and a KOLLNIUN review says the manual includes LiFePO4. The Hoysicy 30 W bullets do not, and a review says it will not charge LiFePO4. PWM is the switching method. The profile is a separate line.
Is a 30 A PWM bigger than a 20 A MPPT?
A 30 A rating is a higher current ceiling than 20 A, not a better tracking method, and the label does not mean 30 A will flow. Compare the voltage limit and the battery profile before the amps.

Related pages

How to connect a solar panel kit

Solar panel kit

Best solar panel kit for a 12 V battery in Britain

How to choose a 12 V solar panel kit for a battery

Solar panel kit for a campervan roof or your pitch

Sources

Public UK sources and the amazon.co.uk listings used for this comparison. Prices and star ratings are the listing lines from 19 October 2026.

  1. GOV.UK: Register energy devices in homes or small businesses (retrieved 19 October 2026)
  2. legislation.gov.uk: GPDO 2015 Schedule 2 Part 14 (retrieved 19 October 2026)
  3. GOV.UK: VAT Notice 708/6, energy-saving materials (retrieved 19 October 2026)
  4. GOV.UK: VAT on energy-saving products (retrieved 19 October 2026)
  5. National Grid: G98 microgeneration (retrieved 19 October 2026)
  6. Electrical Safety First: solar panels (retrieved 19 October 2026)
  7. MCS: why certification matters (retrieved 19 October 2026)
  8. Azeco: PWM versus MPPT charge controllers (retrieved 19 October 2026)