Batteries and banks
Lead acid or LiFePO4, single or in series for a 24V or 48V bank.
Solar and charge controllers
Solar panel wiring diagram: series or parallel
Whether your panels go in series or parallel decides the voltage and the current reaching the charge controller — and therefore the cable size, the fuse and which MPPT fits. Draw both and compare.
Drawing and checking is free and works without an account.
- Free drawing, no account
- Victron components with real terminals
- Checks on cables, fuses and voltage
What can you draw?
Every part comes from the component library with real ports, voltages and currents.
Solar panels
Panels in series or parallel to a charge controller at the right voltage.
MPPT charge controller
Charge controllers between solar and battery, including Victron models.
DC-DC charger
Charging from the alternator or starter battery over a DC-DC charger.
Inverter
From 12V or 24V to 230V for your onboard appliances.
Shore power and charger
Mains connection with battery charger, RCD and circuit groups.
12V and 24V loads
Lighting, pump, fridge and other loads with a fuse per circuit.
230V circuits
Sockets and fixed connections behind your inverter or shore power.
What the app checks
Voltage per string
Panels in series add up, parallel strings keep the same voltage. The check works that out per string and compares it with the controller input.
PV cable and voltage drop
The PV run is usually the longest part of the system. With the length filled in you see how much harvest you lose in the cable.
Battery side protected
Between controller and battery there should be a fuse that matches the cable; that check works the same as for other branches.
Automatic checks while you draw
WireElectric calculates along as you connect parts and reports what does not add up.
Wire size
The required cross-section follows from current, length and allowed voltage drop.
Fuses
A fuse that does not match the cable or the device is flagged.
Voltage drop
Per cable you see the loss in volts and percent.
Connections
Ports that do not match in voltage or type raise a warning.
Parts of a solar system
For the solar section you use, among others:
- Solar panels from 100 W to 500 W, wired in series or parallel
- MPPT charge controllers in different current ratings
- PWM charge controllers for simple systems
- PV isolator, fuse and the cable run to the roof
- Battery bank at 12V, 24V or 48V with busbars and main fuse
- Shunt or battery monitor to follow the harvest
Drawing the solar section
- 1
Choose the panels
Place your panels with their power and voltage and decide whether they go in series or parallel.
- 2
To the controller
Connect the string to the PV input of an MPPT or PWM controller, with an isolator in between if you want one.
- 3
Battery side
From the controller to the battery busbar with a fuse, and a shunt in the negative lead if you monitor the bank.
- 4
Check
Fill in the lengths and work through the findings: voltage, conductor size and protection per connection.
Example wiring diagrams for campervan, boat and off-grid
Calculate it yourself
Every calculator answers one question about your installation. WireElectric then runs the same calculations for every connection in your complete diagram.
Wire gauge calculator
Find the cross-section that suits your 12V or 24V system, based on current, length and voltage drop.
View →Fuse size calculator
Find a suitable fuse for your circuit, including a check on whether the cable can carry it.
View →Voltage drop calculator
Check how much voltage you lose over a cable and what reaches your load.
View →Battery capacity calculator
Work out how much battery capacity in Ah you need for your daily use and autonomy.
View →Battery runtime
Calculate how long a battery can power a load, including the usable share and inverter losses.
View →Watts ↔ Amps
Convert power straight to current at 12V, 24V, 48V or 230V.
View →Solar panel calculator
Work out indicatively how many Wp of solar panels your daily consumption needs.
View →Solar panel wiring diagram: series or parallel
Two panels in series double the voltage at the same current; in parallel they double the current at the same voltage. That difference decides whether your controller can handle the string, what the PV cable needs to be and whether a fuse or isolator belongs in the string. In the editor the panel circuit is judged separately from the battery circuit, so a series string is never flagged as a polarity error.
You can start drawing without an account.
Open WireElectricQuestions about solar in a diagram
- Series or parallel: which is better?
- Series gives higher voltage, thinner cable and less loss, but shade drops the whole string. Parallel copes better with shade but doubles the current and the cable size. Draw both and compare the findings.
- Which MPPT fits my panels?
- Look at the open circuit voltage of the string and the charge current on the battery side. The app works out the string voltage; the controller limits are in the manufacturer's datasheet.
- Do I need a fuse in the PV lead?
- The battery side always needs a fuse. In the PV lead an isolator or fuse is common with multiple strings; follow the manufacturer's guidance.
- Can I use this for a home battery?
- Yes, there is a dedicated page for a 48V home battery system with the same checks on cables and protection.
Also useful
- Back to the homepage
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- Draw the wiring diagram for your boat
- Draw an off-grid diagram with solar and battery
- Draw an electrical diagram without learning CAD
- Build a 12V wiring diagram that adds up
- Draw the electrical diagram of a caravan
- Draw a home battery wiring diagram