Hello Jan,You're right, a capacitor could theoretically help bridge the gap during the switchover from solar/grid to battery power. The short power cut you're experiencing is likely due to a relay switching and the time it takes for the inverter to recognize the loss of grid power and engage the battery system. However, using a capacitor to handle a 10kW load presents some significant challenges and practical considerations.Here's a breakdown of why, and what your options might be

Why a Capacitor Might (Theoretically) Help:
Bridging the Gap

A capacitor stores energy. When the power dips during the switchover, the capacitor could discharge and provide a small amount of power to "fill in" the gap, potentially preventing a complete power loss to your sensitive equipment.

Why a Capacitor is Impractical (Most Likely)



Enormous Capacitance Required

To provide even a fraction of a second of power at 10kW (10,000 Watts), you would need an enormous amount of capacitance. The formula for energy stored in a capacitor is: `Energy (Joules) = 0.5 Capacitance (Farads) Voltage^2` Power (Watts) = Energy (Joules) / Time (Seconds)Let's say you want to supply 10kW for just 0.1 seconds (100 milliseconds). Let's also assume a DC voltage of 48V (a common battery voltage). You'll need to maintain that voltage while the capacitor discharges. To keep things simple, we will do some approximations. Energy Needed: 10,000 Watts 0.1 seconds = 1000 Joules Rearranging the formula: Capacitance = (2 Energy) / Voltage^2 Capacitance = (2 1000) / 48^2 = ~0.87 Farads (870,000 microfarads)However, a more precise calculation considering voltage drop is more complex. The more the voltage drops, the more capacitance you need. For example, if we assumed a 240VAC system and used AC capacitors, this gets slightly better but is still very large and expensive.

Size and Cost

Capacitors of that size, especially ones that can handle the voltage and current required for a 10kW load, are physically large, extremely expensive, and difficult to integrate into a standard residential or commercial electrical system. They are generally only used in very specific industrial applications where momentary power dips are critical.

Discharge Profile

Capacitors discharge in a curve. The voltage drops quickly initially, and then tapers off. This means the power delivered will not be constant and might not be suitable for all loads. You would need sophisticated control circuitry to manage the capacitor discharge and ensure it provides a stable voltage.

Safety Concerns

Large capacitors store a significant amount of energy and can be dangerous if mishandled. A fault in the capacitor or its control circuitry could result in a significant electrical hazard.

Maintenance

Large capacitors can degrade over time, requiring periodic replacement.

Better Solutions


UPS (Uninterruptible Power Supply)

This is the best solution for sensitive equipment. A UPS is specifically designed to provide seamless power during outages. A small UPS can be installed on just the critical circuits you need to protect (computers, networking equipment, etc.). Make sure the UPS is rated for the wattage of the devices it will be supporting, with some headroom (20-30%) for surges.2.

Inverter Settings (Most Likely the Problem)



Transfer Time

Check your inverter's settings for "transfer time" or "switchover time." Many inverters have adjustable settings that control how quickly they switch to battery power. Try setting this to the fastest possible setting (typically a few milliseconds). Consult your inverter's manual for details. This is the first and easiest thing to try.

Voltage Threshold

Another setting to check is the "grid voltage threshold." This setting determines at what voltage the inverter switches to battery. If this is set too low, the inverter might be waiting too long before switching.3.

Inverter Compatibility

Some inverters are just better at seamlessly switching to battery power than others. If your current inverter is known to have this issue, it might be worth considering a different model. Consult with a qualified solar installer who has experience with different inverter brands.4.

Soft Start Devices

If the power cut is only happening when specific appliances turn on (e.g., air conditioner, refrigerator), the inrush current (the surge of current when the appliance starts) might be causing the voltage to dip and trigger the switchover. Consider installing "soft start" devices on these appliances to reduce the inrush current.5.

Battery Capacity

While less likely to be the cause of the short power cut, insufficient battery capacity can exacerbate the problem. If your batteries are deeply discharging frequently, it can put more stress on the system during switchovers.

Recommendation


Start by checking your inverter settings

This is the easiest and cheapest thing to try. Consult your inverter's manual or contact the manufacturer's support.2.

If inverter settings don't help, consider a UPS for critical loads

This is the most reliable solution for preventing disruptions.3.

Consult with a qualified solar installer

They can assess your system, identify the root cause of the power cut, and recommend the most appropriate solution. They can also test the system with an oscilloscope to precisely measure the time and voltage drop during switchover.

Important Note: Working with electrical systems can be dangerous. If you are not comfortable working with electricity, please consult a qualified electrician or solar installer.Good luck! Flag for review