Accessories
Mounting structure, cable, connectors, breakers and charge controllers explained.
Solar accessories · Protection
Solar DC Breakers and SPD Price in Karachi
Breakers and surge protectors cost little next to an inverter, and they are what protect it. This page explains which ones to buy and how to match the ratings.
- ✓ Why DC is different
- ✓ Matching voltage ratings
- ✓ Free estimate on WhatsApp
Why you cannot use an ordinary AC breaker on the panel side
Alternating current crosses zero many times a second, which helps an arc die out when a breaker opens. Direct current from panels does not. An arc on DC burns longer and hotter.
That is why the panel side needs breakers, isolators and fuses rated for DC. An AC breaker used on a DC line may fail to open the circuit and can start a fire. Ask for parts marked with a DC voltage rating, not just a current rating.
Solar protection falls into two groups. Breakers and isolators switch the circuit off. Surge protectors divert voltage spikes away from the equipment. A good system has both.
Breaker and SPD prices we quote
Prices change with the rating and the dollar rate.
| Item | Detail | Price (PKR) |
|---|---|---|
| DC breaker | Rated for your array voltage | Contact us for latest prices |
| DC surge protector (SPD) | For the panel side | Contact us for latest prices |
| AC surge protector | For the inverter output side | Contact us for latest prices |
Prices change with the exchange rate and stock. Contact us for the latest prices.
Where each part goes
A typical home system uses this set. The exact list depends on the inverter and the layout.
| Part | Position | What it does |
|---|---|---|
| DC isolator or breaker | Between the panels and the inverter | Lets you switch the panel side off safely |
| String fuse | On each string, when several are combined | Protects the cable from a fault current |
| DC surge protector | On the panel side | Diverts spikes before they reach the inverter |
| AC breaker | On the inverter output | Protects the output cable and the board |
| AC surge protector | At the distribution board | Limits grid-side spikes |
| Earthing | Connected to frames and the SPD | Gives surges a safe path to ground |
How to match the DC rating
The sum is simple, and getting it wrong is dangerous.
- 1
Find the open-circuit voltage of one panel
It is on the datasheet. Many 585 W panels are around 50 to 53 V, so check yours.
- 2
Multiply by the panels in one string
Ten panels in series at about 52 V give about 520 V.
- 3
Choose a rating above that
The DC breaker, isolator and SPD must be rated higher than the highest string voltage. Many are rated for 1,000 V DC.
- 4
Check the current rating
The breaker current must suit the string current, with a margin, and the cable must carry it.
- 5
Check the standard
Look for the standard on the part. IEC 60947-3 covers switches and isolators, and IEC 61643-31 covers surge protective devices for solar systems.
Surge protection and the earth
A surge protector only works if the earth is good. It sends the spike down the earth wire. A weak or missing earth leaves the spike with nowhere to go but into the inverter.
Karachi has a monsoon season from late June to September, and storms can bring lightning and grid spikes. A surge protector is cheap compared with an inverter, so ask for both DC and AC protection.
Ask the installer to test and record the earth reading, and to show you the surge protector status window. Many have a window that changes colour when the protector has done its job and needs replacing.
What to avoid
Avoid breakers with no printed voltage rating, unbranded SPDs with no standard marking and any quote that leaves out earthing. The cheapest protection is the first thing a poor quote cuts. See how a full quote should read in our system size guide.
FAQs
Questions people ask us
Short answers. For your own property, send us your electricity bill and roof details.
Ask on WhatsAppIt depends on the voltage and current rating and the brand. Send your array details and we will quote the right size.
No. DC arcs do not die out as AC arcs do, so you need parts rated for DC voltage.
We recommend it on both the DC and AC sides. It costs little compared with an inverter.
Surge protective device, also called a surge protector or arrester.
Check the status window or indicator. Replace the unit when it shows it has been used up, and after a heavy storm.
Related pages
Charge Controllers
MPPT and PWM charge controllers, with the sums to size the right amp rating.
3 kW, 5 kW, 6 kW Systems
3 kW, 5 kW and 6 kW systems: output, roof area, loads and quote checks.
Installation
The installation process, how to vet a solar company and Karachi site issues.
Need protection for your system?
Send your array and inverter details. We will quote the right breakers and surge protectors with a free estimate.