Understanding Grid-Tied Solar Systems
how's it going you guys it's Scott with everyday solar and I want to go through some of the basic components on a grid tied solar system now for many homeowners it's kind of like drinking from a fire hose there's a lot of different components a lot of different terminology a lot of different calculations so I want to break it down into digestable chunks specifically only focusing on one component at a time and today we're talking about a combiner box now when it comes to a grid TI system if you have a combiner box that means that you're using mic micro inverters at each one of your PV solar panels microinverters will be located on the rails right underneath your PV solar panels and they're actually converting the DC power from the panel over to AC right at the micro inverter and then the AC power is being combined together and then lands within a combiner box
Enphase IQ Combiner 4 Introduction
Now there's many different brands and different types of combiner boxes but this is going to be one of the most common you'll see out there and it's made by nphase this is their IQ combiner 4 and it has capability of bringing in four different strings each string going into a 240 volt 20 amp eaten circuit breaker with an additional 15 amp circuit breaker here also two or 40 volts but this is not bringing in any of the power from the PV panels This is just powering the overall smarts of the envoy system here now this combiner box is part of an 11.3 KW grid tide system that I just had installed in house it cost me $37,000 which is a large chunk of change and if you guys are just considering solar check down a link in the description below this video and that will jump you over to where I started I started sizing out my system and getting an estimate on the cost that cost estimate was pretty accurate on the high side I was all the way up on the high side and remember that cost estimate you're getting is after a 30% federal tax credit but this combiner box has a big old plastic cover on on it I do not recommend you taking the cover off especially when it's on but I'm going to open this up to give you a little bit more of the guts of a combiner box which will help things make a lot more sense
Internal Components and Operation
so now with that cover removed you can really see what's going on we have in and out when it comes to our wires in brings together all the different 10 gauge stranded runs coming from your panels on your roof or your ground mount for me I have three different strings one is nine panels the other is nine panels and my last is 10 panels now this is 10 gauge usually for a 20 amp breaker say home or residential you could use 12 gauge but because this is such a long run they use a thicker gauge wire to reduce what's called line losses so that's why they're using 10 gauge here each of these these 20 amp 240 volt Breakers are mounted to a common bus bar very similar to your main panel or subpanel in your home and then you have two different phases going down to these main lugs and then this black conductor and this red conductor which are stranded THHN 6 gauge now those are going to tie into your panel this is what's grid tying us tying us to the utility we have that 15 amp that is going over and powering your circuit board and that is that Envoy system that is the smarts of the operation and then you will have a current clamp over here that is monitoring the black side of your three different strings so that's measuring the current coming through all three of those strings together and then you will have two different bus bars on the bottom one is going to be your ground bus bar and the other is going to be your neutral bus bar
Combiner Box Purpose and Safety
and that's pretty much it that is the guts of the combiner box box the whole purpose is to bring together all the different AC power from the different strings coming together bring those into one combiner box and then bring those over to your home to your main panel whether you're going into a breaker on your main panel or you're doing what's called a line side tab so hopefully that gave you a little better understanding of a combiner box and again I do not recommend you take the cover off and poke around especially when everything is up and running let me know if you guys have any specific questions down in the comments and I love DIY setups smaller setups just to get started in solar it really starts to help you understand those different components and not everything translates over to a grid tied system but it really does start to help you understand what's possible from solar and honestly it's just fun so if you want to test out a very simple DIY setup check out this video right here I'll walk you through all the different components and how to get up and running in the same day so thanks for joining me on this video and we'll catch you on that next one take care
Technical Specifications: Enphase IQ Combiner 4
| Feature | Detail |
|---|---|
| Model | Enphase IQ Combiner 4 |
| Input Capacity | Up to 4 PV strings |
| Input Breakers | 4 x 240V, 20A circuit breakers (for PV strings) |
| System Breaker | 1 x 240V, 15A circuit breaker (powers the Envoy system, which includes monitoring and control functions, often referred to as the "enphase smart switch" or system intelligence) |
| Input Wiring | 10 gauge stranded runs (from PV panels) |
| Output Wiring | 6 gauge stranded THHN (black and red conductors to main panel) |
| Bus Bars | Common bus bar for breakers, separate ground and neutral bus bars |
| Monitoring | Current clamp monitoring the black side of PV strings (for overall current) |
| Nominal Voltage | 240 Volts |
Frequently Asked Questions
Q: What is a combiner box in a grid-tied solar system? A: A combiner box is where the AC power from different strings of microinverters (located at each PV solar panel) is combined together before being sent to your home's main panel.
Q: What is the purpose of the 15 amp circuit breaker in the Enphase IQ Combiner 4? A: The 15 amp circuit breaker in the Enphase IQ Combiner 4 is not bringing in any power from the PV panels; it is just powering the overall smarts of the Envoy system. This Envoy system acts as the intelligence and monitoring hub for the solar installation, which can be thought of as a central "enphase smart switch" for system management.
Q: Why is 10 gauge wire used for the PV strings instead of 12 gauge? A: For a 20 amp breaker, usually 12 gauge wire could be used residentially, but because this is often such a long run from the panels, a thicker 10 gauge wire is used to reduce what's called line losses.