Skip to main content
Observer Ethical awards Winners 2011

YouGen Blog

How closely should the input of an inverter match the output of a solar array?

Posted by Chris Rudge on 18 November 2013 at 10:31 am

Q: How important is it to match the Max DC input of the inverter, to the maximum possible output of the solar array? Some companies have given me quotes where the output/input are miles different.

A: It is standard procedure to install an inverter that is up to 20% lower in power rating than the array. Inverters run at a better efficiency if matched to the input power. The full generation capability of the array is limited by factors such direction of the array, time of year and most importantly, weather!

Because of these factors, the amount of times a year the array will be generating full output is limited in a standard UK climate. If the array is 2kWp and a 2kW inverter is installed the inverter may potentially not even turn on in cloudy conditions. However, if the inverter installed is, say, a 1.5kW type, lower light levels would still generate power.

More information on YouGen

YouGen guide to solar PV

Who deals with claims over an inverter warranty?

Inverters for Solar PV panels: your questions answered

Picture: SMA Solar Technology

About the author: Chris Rudge is a qualified electrician who specialises in renewable energy.

If you have a question about anything in the above blog, please ask it in the comments section below.

Like this blog? Keep up to date with our free monthly newsletter


2 comments - read them below or add one


vespecComment left on: 24 October 2015 at 3:29 pm

Looking for advice,

I am installing 3 x 250w panels to a static caravan, have the oppertunity to purchase a sunny roo inverter 3000, i know the inverter is way over the odds for a 750w array but would this make a difference to the performance....

report abuse

richly comic

richly comicComment left on: 27 April 2015 at 4:47 pm

We had a 2.5kW system installed a year ago, including access to an online monitoring system.  We haven't had any problems with the installation.  However, we've recently discovered that whilst it is a 2.5kW system, the inverter is 2.0kW. This has come to light with the glorious weather in April; when reviewing the charts you can see a jagged effect around 2kW, and nothing exceeding 2.04kW.


Should I be concerned about this?  Clearly I can see that currently we are losing out, but appreciate that most of the year 2kW is not reached.


I've read mixed information, and conflicting too.  One school of thought is that a smaller inverter is more efficient, and another that the inverter needs to be bigger to prevent overheating.  Which is correct?


Unlike some of the comments regarding quotations on here, we were never told the inverter would be smaller than the installation, and no explanation was provided.  More importantly the contract specifically states the installation will include 2.5kW panels and a 2.5kW inverter, so if nothing else I could have the installer on breach of contract.

I’d appreciate your comments.

report abuse

Leave a comment

You must log in to make a comment. If you haven't already registered, please sign up as a company or an individual, then come back and have your say.