A big trend in residential solar + storage is sourcing full systems from a single vendor when possible. One of the leaders in this space is Qcells, which ranks No. 1 in terms of residential solar panel market share, and also has a compelling home energy storage system.
On this episode of The Pitch, Qcells Head of Engineering Dru Sutton, provides a good overview of the Q.HOME CORE ESS (battery, inverter, energy management hub), and the benefits of sourcing from a single provider. Watch the full 12-min video here. Part of the transcript is below.
- 0:35 – Overview Q.HOME CORE ESS
- 1:24 – Q.VOLT battery design that saves floor space, eases installation
- 2:33 – Trends in battery system sizing
- 3:47 – Benefits of sourcing ESS + solar from a single supplier
- 4:35 – Q.VOLT inverter specs to know
- 5:47 – Retrofitting ESS to existing home solar system
- 6:44 – Sizing Q.HOME CORE ESS for California NEM 3.0
- 9:14 – UL 9540A explained
- 10:20 – ESS installer training and Qcells Partner Program
- 11:19 – Qcells U.S. supply chain news
Sutton: The basic system of the Q.HOME CORE consists of three main components. The first one we call the Q.VOLT inverter. That’s a 7.6 kW inverter, pretty standard size, and that connects into what we call the Q.SAVE batteries. Each one is 5 kWh, and you stack up to four of them to a single Q.VOLT inverter to provide a 20 kWh battery. And then connecting them all together and the connection to the actual electrical service panel is a device we call the Q.HOME HUB. … Communications is in there, the transfer switch, and such, to make the system complete.
Crowell: I wanted to start with that first visual. What stood out to me is the shape of the system versus other energy storage systems I’ve seen. It’s kind of tall; it has that thin profile.
Sutton: The Q.HOME CORE is our second generation, if you will. Some strong customer feedback was that installers wanted a system that, first of all,could be easily installed, and secondly, one that didn’t take a lot of floor space. So, when we figured out the architecture for this, we came up with this concept where the Q.HOME battery system in the hub actually sits just off the wall and is thin like that.
This has a couple benefits. One is it becomes very easy to install. It kind of goes together like LEGO blocks — you stack the different components together with little to no wiring. Secondly, many people will put the system in their garage, and this shape takes up very little of the valuable floor space in there and gives you a lot of options of being able to mount it in different locations either in the garage or outside.
Crowell: In terms of scalability of the battery, you mentioned the 5 kWh building block. I see various system sizes trying to cater to a whole home backup but then also trying to cater to NEM 3.0, and not needing a super huge battery to just save some solar and not export to the grid. Can you walk us through your various system sizes and what you’re seeing customers gravitating toward?
Sutton: There used to be a trend as, you said, bigger is better. But now, with NEM 3.0 in California, we see there’s a sweet spot for a system that would have like a 10 kWh battery. The way we’ve developed our system is the minimum size of system that we can support is 10 kW. A system can also do 15 or 20 kWh as well with the 5 kWh battery blocks that would plug into the system. We also have the ability to scale and put multiple inverters together.
Crowell: You’re also, as a part of this, promoting an integrated rapid shutdown solution. Is that a unique feature? And I was curious if that maybe only applies with integrating the system with Qcell modules that have a specific junction box.
Sutton: The goal of Qcells is to source full systems from a single supplier. So we actually provide a rapid shutdown device. It’ll go on any module but of course the benefit of going to Qcells is you would put it behind a Qcells module and connect all that together with our Q.HOME CORE device. It’s an external device that plugs right into the cables coming out of the junction box in our Qcells module.
Crowell: Any other features or spec sheet stats that you wanted to point out?
Sutton: The 7.6 kW inverter of course is the industry’s standard. One of the things we did also develop in that inverter was the ability to oversize — meaning that you can actually put more than 7.6 kW of dc power going into it. We actually allow a 2x oversizing, which means you can put up to roughly 15 kW into a single 7.6 kW inverter. You might consider doing that because the way the inverter works is any unused dc power going into the inverter can actually directly go into our batteries, which means, if you had 10 kW going into the inverter, and you were using 7.6 ac output, the other approximately 2.5 kW can directly charge the battery. That’s an interesting feature that hybrid inverters have.
Crowell: In California under NEM 3.0, offering battery systems without microgrid interconnection devices that can only operate in self-consumption mode is increasingly popular. Is there an approved Q.HOME CORE configuration that allows for a time of use optimization without full backup capability?
Sutton: Absolutely. There’s actually there’s actually three use cases. The full up system that we’ve been talking about includes the ability to do either whole home backup or partial home backup. For California, there seems to be a great use for having a lower cost version where you don’t have the backup. So, we call that grid service. In other words, that system contains the Q.HOME CORE and the Q.SAVE battery but no Hub. On the installation side, you don’t have to worry about connecting either partial home backup or full home backup, but you still have the battery to discharge in accordance with NEM 3.0 in California.
We also have another option which we call solar-only, and we actually see a market for installers and customers who just want just a solar electric system, and it’s completely sourced from Qcells — it’s Qcells panels, Qcells shutdown device, Qcells inverter, and that’s gaining in popularity with some of the installers because it’s a system 100 percent sourced from Q cells.
It’s a single point of contact not only to purchase all the components but also one place to call to get help. You’re talking to someone who can answer module questions, inverter questions, battery questions.
Crowell: Does Qcells offer any type of training courses on how to design and install the Q.HOME CORE system? And also, just thinking about the full product suite from modules to inverters to storage, do you have an installer program to get preferred pricing or anything like that?
Sutton: It’s very helpful to help train installers how to not only install it but also how to design it. How much battery should you put on a house? How do you do the single line drawing? Where do you connect into the service entrance? These are a lot of new things that many installers are not used to, so we offer a full online training course that goes through how to design with a Qcells product. And once you have completed the course, it allows you to become able to join the Qcells partner program. If you go to qcellspartner.us it lists all the benefits of that.
— Solar Builder magazine