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How to connect a solar charge controller

Updated: October 2026

The controller, the panel, and the battery are on the bench. How to connect a solar charge controller comes down to one order that six listings in this amazon.co.uk set actually print: battery first, then the panel, then the load. UK reviews in the same files include a USB port that smoked, a case that melted in a shed, and displays that never came up. This page is that sequence and the point where you stop. Ranks and prices stay on the [solar charge controller comparison](/hub/electrical-equipment/solar-charge-controller). This is not a substitute for BS 7671 where the wiring is part of a fixed installation. A qualifying Amazon purchase can earn us a commission at no extra cost to you.

The controller, the panel, and the battery are on the bench.

Our top picks

Victron Energy Victron SmartSolar MPPT 100/15

Best overall

Victron Energy Victron SmartSolar MPPT 100/15
8.6/10about £61.60
View offer
Topcloud Topcloud 10A PWM

Best value

Topcloud Topcloud 10A PWM
7.2/10about £8.96
View offer
AeternaSol AeternaSol 10A 12V MPPT

Rank 3

AeternaSol AeternaSol 10A 12V MPPT
5.5/10about £18.99
View offer
On this page
  1. 1.Connect the battery before the panel
  2. 2.Set the battery type before you trust the numbers
  3. 3.Use the load terminals only for a small DC load
  4. 4.Stop if it is hot, blank, or smoking

Connect the battery before the panel

The controller has to see battery voltage before it sees the panel. Renogy's Rover installation text says to connect the battery terminals first and never to connect the panel before the battery. Inside this capture, that order is printed on the AeternaSol 10 A, the Topcloud 10 A, the Rolokit 30 A, and the Depvko listing whose title says 100 A. The Victron SmartSolar and BlueSolar captures do not print that sentence, so for those two you follow Victron's own manual. A fuse belongs on the positive lead, close to the battery, sized to the cable you actually fitted. Do not paste a Victron fuse rating onto a PWM unit that never published a terminal rating. A flat battery can be read as the wrong system. When you take the system apart later, reverse the order. Panel off first, then the load, then the battery.

Set the battery type before you trust the numbers

A lit display is not proof that the charge profile matches the battery. The Rolokit 30 A and the Depvko 30 A say lead-acid only, and they say not to charge lithium. The Topcloud 10 A and 30 A name lead-acid, ternary lithium, and LiFePO4, and they tell you to select the mode on the LCD before use. The AeternaSol 10 A names LiFePO4 on a 12 V system and says it is not for 24 V. The SmartSolar bullets talk about battery presets in the app and do not list the chemistries in the captured text. If you have not chosen the chemistry yet, stop and use the solar charge controller buying guide before you close the cover.
Victron Energy Victron SmartSolar MPPT 100/15

Testsieger

Victron Energy Victron SmartSolar MPPT 100/15
8.6/10about £61.60
View offer

Use the load terminals only for a small DC load

The load screws are not a second battery terminal and they are not an inverter socket. Renogy's Rover manual says not to put an inverter on the load terminals. The Topcloud 30 A states 30 A of charge and only 10 A of discharge. The Y&H 60 A states 30 A of discharge against a 60 A charge title. A 1,000 W inverter is not. USB is a smaller rail. The Rolokit states 5 V / 3 A. In the UK reviews, a Rolokit USB port smoked after a few minutes, and the Depvko 30 A rear gets hot when the USB ports are used. Charge a phone if you must, and unplug it if the case warms up.

Stop if it is hot, blank, or smoking

Stop when the signs in these UK reviews show up. The Topcloud 30 A sample includes a unit that burned and melted in a shed. The AeternaSol 10 A smoked and failed within seconds of being plugged into a portable panel. A blank display is not always your wiring. Topcloud reviews include a display dead on arrival. If you see smoke, melted plastic, or a case you cannot touch, isolate the panel and the battery, and do not put the unit back. A 12 V controller on a shed battery is not permission to feed a ring final. Van roof mounting belongs on the solar charge controller for a campervan page. If you are still choosing which box to wire, the shortlist is the best solar charge controller page.

Common questions

Do I connect the battery or the panel first?
Connect the battery first, then the panel, then any load. Six listings in this set print that order, and the Renogy Rover manual says never to connect the panel before the battery. The Victron SmartSolar and BlueSolar captures here do not print the sentence, so use Victron's manual for those two.
Can I run an inverter from the load terminals?
No. Renogy's Rover manual says not to put an inverter on the load terminals, and the discharge figures here are small. The Topcloud 30 A states 10 A of discharge beside a 30 A charge rating. Use the load port for a lamp or a pump inside that figure.
The display is blank. Did I wire it wrong?
Sometimes. Battery first, with enough voltage for the unit to recognise 12 V or 24 V, is the check. A flat battery can fail that step. Sometimes the unit is dead. UK reviews in this set include a Topcloud display dead on arrival and a Depvko that would not switch on.
The case is too hot to touch. Do I leave it?
No. Isolate the panel and the battery and leave the unit out. Reviews here include an AeternaSol 10 A that was too hot to touch, a Depvko that overheated toward melting, and a Topcloud 30 A that melted in a shed. A case you cannot hold, or smoke, means the job is over for that unit.
When do I stop and call someone?
Stop if there is smoke, melted plastic, or a connection that would feed the house mains. A shed battery that never touches the consumer unit can stay a 12 V job. Export into the distribution network, or any wiring you cannot prove dead, needs a competent person.

Related pages

Solar cable

Solar charge controller

Best solar charge controller UK: which listing fits

Solar charge controller buying guide, voltage first

Solar charge controller for a campervan, 15 W or 15 A

MPPT or PWM solar charge controller: voltage first

Sources

Public UK and manufacturer sources are listed below. Shelf prices and star lines are the amazon.co.uk figures captured on 19 October 2026.

  1. Victron Energy, BlueSolar MPPT installation (75/10 to 100/20) (retrieved 19 October 2026)
  2. Victron Energy UK, solar charge controllers (retrieved 19 October 2026)
  3. MCS MIS 3002 (2026), solar PV systems (retrieved 19 October 2026)
  4. Electrical Safety First, solar panels (retrieved 19 October 2026)
  5. Electrical Safety First, plug-in solar consumer guide (retrieved 19 October 2026)
  6. GOV.UK, fire and solar PV recommendations (retrieved 19 October 2026)
  7. IEA PVPS, Recommended Practices for Charge Controllers (retrieved 19 October 2026)
  8. Consumer Rights Act 2015, section 22 (retrieved 19 October 2026)