HOW SOLAR REALLY WORKS PART 1
Hi, Electrical engineer here working in solar. To give you a brief explanation on how solar really works, let’s talk about the basics.
Solar power starts with photovoltaic panels that convert sunlight into direct current electricity. This DC power then goes to an inverter, which converts it into alternating current that your home or facility can actually use.
From there, the power either supplies your loads directly, charges a battery storage system if you have one, or gets exported to the grid in a grid tied setup. An Energy Management System can help decide where the power should go depending on demand, battery state of charge, and grid conditions.
1. What are the different types of solar setup
A grid tied system is connected to the utility grid. It does not require batteries in most cases. Solar power is used first for the loads, and any excess is exported to the grid. If solar is not enough, the system pulls power from the grid. This is the most common setup for residential and commercial buildings.
An off-grid system is completely independent from the utility grid. It always requires batteries because all excess solar energy must be stored for use at night or during low sunlight. These systems are commonly used in remote areas where grid access is not available.
A hybrid system combines both grid connection and battery storage. It can use solar power first, store excess energy in batteries, and still connect to the grid as backup. It offers more flexibility, better energy security, and can be optimized using an Energy Management System.
2. What is the difference between kW, kWp, and kWh
kW or kilowatt
kW is a unit of power. It tells you how much electricity is being used or produced at a specific moment.
Example, a 5 kW load means the equipment is consuming 5 kilowatts right now.
kWp or kilowatt peak
kWp is the maximum rated power output of a solar system under ideal test conditions. It is basically the nameplate capacity of solar panels.
Example, a 10 kWp solar system means the panels can produce up to 10 kilowatts under standard test conditions.
kWh or kilowatt hour
kWh is a unit of energy. It tells you how much electricity is used or produced over time.
Example, if a 1 kW load runs for 1 hour, it consumes 1 kWh of energy.
Real life analogy
kW is like how fast a car is going
kWh is like how far the car travelled
kWp is like the car’s top speed rating under perfect conditions
3. Why does my solar system not reach maximum capacity starting with the panel
What is the rated panel capacity or kWp
Solar panels are rated under Standard Test Conditions, which assumes perfect sunlight of 1000 watts per square meter, panel temperature of 25 degrees Celsius, and no losses. This is where the “maximum” kWp value comes from.
STC
NOCT
Please note:
A solar panel does not usually reach its maximum kWp rating because that value is based on Standard Test Conditions, which assume perfect sunlight, ideal temperature, and no losses. In real world operation, output is reduced by higher panel temperature, varying irradiance throughout the day, suboptimal slope or tilt angle, incorrect orientation relative to the sun path, cloud cover that reduces direct sunlight, shading from nearby objects like trees or buildings, and soiling such as dust, dirt, pollution, or bird droppings that block sunlight from reaching the cells.