Homebrewed Electricity > Solar
What happens when you generate more than the inverters rating?
jasonmanning:
The efficiency of an inverter determines the efficiency of a solar panel because inverters convert DC into AC. If more power is generated it is clipped down. The device will have an inbuilt charge controller which prevents batteries from overcharging. 8)
Ungrounded Lightning Rod:
--- Quote from: Valalvax on September 05, 2012, 11:47:30 AM ---So what your saying is if I have 5 panels in series, and I want to add panels in parallel, I'll need to add 5 in parallel?
--- End quote ---
You'll need to add, in parallel with the five-in-series, another five-in-series (or other arrangement that produces the same voltage, or reasonably close to it). Panels are current sources with a maximum voltage and are quite happy to have their output dragged down to a lower voltage, or even shorted to zero. (When shorted they dissipate the same amount of heat as if they were unconnected - just more of it is in the conductors rather than distributed through the semiconductor.)
But they don't like being back-fed a higher voltage than they can produce. When you start paralleling strings of panels, you want to put a protective diode in series with EACH string, to keep all the strings feeding the output rather than pushing current backward through another panel that is a lower-voltage or has a shadow over part of it. Exceeding the peak reverse voltage of the cells can destroy them. Adding the diode may cost you a small amount of power due to its voltage drop, but it's a drop in the bucket compared to what you gain by adding another string of panels - or lose if a string of panels is destroyed by reverse-current.
Re: Big panel farm, small inverter. Addressed above (it's fine) but consider this: If the panels are charging a big bank of heavy-duty batteries, the batteries COULD produce tens or hundreds of kilowatts (for a short time) if they were loaded hard enough to do so. Like any other load on a power system, an inverter pulls enough current from a (somewhat soft) voltage source to do its job. If it's JUST an inverter, it's fine. (And you can even connect multiple inverters, for various loads and purposes, to a common battery bank fed by multiple strings of panels that produce far more power than all the inverters combined. The extra power just charges the batteries for use after the sun goes away.)
But if they're NOT just inverters there may be an issue. Some inverters also include charge controllers, or have some charge-controlling behavior (like MPPT voltage-conversion, dump load switching, etc.) These may be designed to assume they're the only such device in the system. In cases like that you may need to give them their own panel subset that's small enough for them to handle. Depending on how well their various systems play together (for instance: low-voltage-shutdown is just fine), you may be able to use a big common battery bank and pool the power from all the panel subsets for evening use, or you may need to have separate battery banks as well as separate panel arrays, for each, or some, of the devices.
Re: Responding to years-old posts. This one's a "sticky" and always at the top of the list of articles in the overall board index. New users will be reading it for years into the future. So if there's something confusing (or wrong) it's still useful to correct it - for their benefit, even if the original poster has long since dealt with the issue and moved on.
Alice Miller:
When the maximum power is exceeded, it is likely to cause damage to your inverter and even the rectification of the solar system. I suggest you add an inverter more, or replace with a higher power inverter.
camillitech:
--- Quote from: Alice Miller on May 10, 2022, 11:13:07 PM ---When the maximum power is exceeded, it is likely to cause damage to your inverter and even the rectification of the solar system. I suggest you add an inverter more, or replace with a higher power inverter.
--- End quote ---
Not so, I ran 3kW of PV through a 1200W Sunny Boy inverter for years in my 'AC coupled' off grid system. I had to do this cos I also had a 6kW wind turbine and 1kW hydro turbine 'AC coupled' and my 6kW off grid inverter couldn't cope with all the power back feeding into my batteries. Only recently upgraded my 1200W Sunny Boy to a 3800W Sunny Boy cos I upgraded from a 6kW off grid inverter to a 10kW one. It is quite common to undersize GTI's to maximise production if your export needs to be constrained.
Cheers, Paul
Amy:
If you generate more power than your inverter's rating, it can result in a decrease of efficiency and cause damage to the inverter. Additionally, it could also increase the risk of fire or personal injury due to electrical overload. It is important to make sure you are not overloading the inverter by verifying that the total solar output is less than the inverter rating. If you need to increase your solar output, you will need to upgrade to an inverter with a higher rating before doing so. Ultimately, it is always best practice to match the inverter's rating as closely as possible with the total solar output of your system.
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