5 Worst Solar System Design Mistakes (And How to Spot Them)

A badly designed solar system will cost you more money than no solar system at all. And the frustrating part is that most homeowners have no idea their system was designed wrong until they’re 2 years in and they realize the savings just aren’t there. I’m Jason. And I’m Cam.

We’re the owners of Source Energy Group, where we’ve designed and installed countless solar and battery systems for Australian homeowners. In this episode, we’re walking through the five worst solar system design mistakes we see so you know exactly what to look out for and what to check with any installer before they touch your roof. Welcome back. Hey Cam.

Hey Jay. Hey Delphy. Hey Delphy. Oh hi.

Back again mate. Damn. You can’t get rid of me. That’s it.

Delphy for whoever hasn’t been listening. Start listening as always. And uh Delphy works in our office. uh she is our PR manager and uh does all our connections and is one of the first points of call in the admin team. Hey guys, bloody beautiful uh talking about the five worst solar system design mistakes that uh homeowners might see.

Um we got Will they see it? The thing is they probably don’t realize it’s happening. Exactly. So what do you reckon number one is there, Cam?

Uh, I’m going to go choice of company would probably be number one. I agree. Yeah. Yep.

Choice of company. It’s uh Yeah, we we carried on a fair bit in the previous episode and almost every other one, but everything really does fall back to the because that’s the underlying cause of the of the mistakes, isn’t it? Yeah, 100%. Always always.

Yeah. We’ve also Yeah, we got shading is probably another big one. Uh the design error that’s that’s pretty big. Um, I had actually had a job recently was an insurance job we were requested to do.

Um, and the the panels existing on the roof had hot spots all over them. We were requested to go there and swap out that entire roof system by insurance and they I I mentioned the hot spots were likely caused by the shading events. Anyway, I mentioned we should at least like trim some trees, work on uh fixing the shading side of things, maybe jig the design, even add optimizers to the panels. They weren’t really happy to do any, so we just can the job.

So, I obviously understand what you mean there, but just for the listeners and the people that are, you know, looking into solar and trying to understand, you know, what these mistakes and what to avoid are, seems simple to us that shade’s an issue cuz obviously the solar panels need the sun to produce the power. Yeah. But, you know, in layman’s terms, what is the shade doing to those panels? Obviously, you just mentioned it’s going to cause hot spots.

Can you break it down real simple? Like, you know, explain it, Woody. Yeah, essentially, yeah, that panel’s uh just trying to operate to its its maximum capacity without the ability to, I suppose. Um, you’re only going to operate as good as your shittest panel.

So, all that power is trying to trying to go through and be used somewhere. I don’t know exact technical terms here, but yeah, I guess kind of leads into another one like in the system design and that. So obviously when you put the panels on the roof, your inverter has different strings or MPPT. Yeah.

Um so when the panels are in the shade and one panel in that string is in the shade, that brings the whole string down, doesn’t it? And it stops performing. Yeah. 100%. And the optimizer you’re talking about, what’s that role or what happens if the optimizer is not in place?

Uh, so that optimizer will uh drop that panel out of that string to stop the rest of the panels dropping down to as low as it is. It it’ll drop it out of the like stop it from dragging it down essentially. Yeah. And part of that what drags that down is if there’s no optimizer to isolate that shaded panel from the string, it actually sends reverse currents back through the string, doesn’t it?

And that’s what causes the hot spots. Yeah. Obviously not being an absolute expert on the optimizer side of things, but for what they do, if you just add optimizers to every single panel on a completely shaded roof, is it going to help production wise? Well, it’s not going to your system’s not going to perform, is it?

Like as if it’s in the sun. And I guess people I’ve spoke to over the years, they’ve been sold optimizers as if it’s fine. You’re in the shade, just put the optimizers on, you everything’s good. Yeah.

The reality is what the optimizer is doing, its role is to stop that reverse current going back through the string to stop the hot spots. Yeah, it’s not going to make your system perform in the shade. It’s just to stop that reverse current, everything, as I said. So, they’re still going to produce in the shade, but if you read the fine print on the optimizers, they say it’s going to produce at roughly 20 to 30% more than if you didn’t have the optimizer there.

So, without the optimizer there, it’s not going to perform. Yeah. So 20 to 30% more of nothing is still basically nothing. Nothing% there’s no win.

So I guess you got to read the fine print and understand what the actual optimizers for. And y when we’re talking about would you call them the JV hi-fi? JVI. Yeah.

Y they’re telling people that the optimizer is going to make your system work in the shade when it’s they have a specific role for shade but they’re not going to make your system perform. Yeah. though if you do have shade 100% you got to put those optimizers and we recommend doing it on the whole every panel on a string don’t we? Yeah. So that means just one sword.

Yeah. That means obviously there’s going to be a portion of the day when in the shade there’s going to be another 6, 7, 5, 4, whatever hours where it’s going to be in sunlight and they’re going to be producing full capacity during that time. But as they go into the shade that’s when they’re not going to produce at full. Okay.

And that’s when again comes back to we always talk about being designed for your house. If you’re getting a design done and you got trees on one side of your house which are going to cause some kind of shade, this should be taken into account into production, shouldn’t it? Yeah. Because that production number is going to affect your so-called savings.

And again, if someone’s designing your system in the shade and they’re not allowing for a 20% 30% 40% production loss based on whatever is relative to that shade, well then the numbers they’re showing you are just all horseshit. Yeah, likely case. Likely case. Yeah.

Couple other common mistakes here which Yeah, we’ll roll through them. Massive one, I reckon, especially with the battery side of things would be not assessing the property’s max demand. Y uh so if a customer requires X amount of like solar and battery, um you you got to have a look at what they’ve got in their house. You got to have a look at what they’re what what they actually use.

Like they might have five air conons, they might have two, they might have three TVs, they might have one, they might have two fridges, they might have one. Um, air con size is big one too. Like obviously if it comes into three-phase power and they got they could have an 8 kW ducted, they could have a 16 kW ducted or something in between, the size of the inverter you choose makes a big difference, doesn’t it? Oh definitely.

That is a big one which has sort of stopped now. 5 kW per phase and you can’t imbalance. Um, but we used to see it all the time back in the day um when we were working at another company that we’re not allowed to talk that’s not our experience. That’s uh Yeah, people putting singlephase inverters on three-phase properties. Yeah, that’s a that’s a big no no cuz then you still got like so on a three-phase property, you got uh power hooked up to or power lighting hooked up to three separate phases over it.

If you’ve got an inverter or solar on just one of those phases or even just battery on just one of those phases with a single phase inverter, you’re only saving on that phase and whatever’s hooked up to that phase. The same with a dual phase property as well, some people just sell it to them. Yeah. But also on the demand as you’re talking about, you know, um if you only got a 5 kW inverter or 10 kW inverter and you got a 16 kW ducted system running at full ball, you’re always going to be drawing from the grid at some point.

Oh yeah. roughly 6 kW does the math. Yeah. Well, I guess on that same one with demand too and technology is constantly changing. I’m not just talking sol shifting to EV.

So, if their home’s been designed or the systems been designed for their current usage, and I’ve talked about this all the time, it’s probably already under sized, especially if they’re planning for an EV in the future or a couple of EVs. Yeah. you know, you start charging your EV from home. Yes, you’re saving on your fuel, but your power bill is going to increase. So, if you’re going to spend the money on your solar and battery and you know you’re 100% getting that EV in 6 months, 12 months time, spend the money now and size for it.

Absolutely. That demand. I char Yeah. charged the EV overnight and had the heater on a stupid setting. Um Yeah.

Killed me battery. Not killed it dead. Like just Yeah. Died almost.

Drained it. Yeah. Yeah, that’s it. Like I only still only pulled 4 kW from the grid, so it must have nearly lasted.

But well, the property demand is probably actually one of the biggest mistakes to be honest. It’s like it comes back to what we always say about designing it properly around the usage. Yeah. And the demand is is usage, isn’t it?

Oh, 100%. And yeah, not looking at usage trends like that that’s I guess pushes into summer, winter. Yeah. like how does a customer use like in the in the summer I don’t really use the air con at all in the winter I’ll use the heater or heat I hate winter passionately I guess it comes back to using the average like your bill your power bill will come through your daily um usage as an average but if you use that you’re still going to get pretty close to the right size system but depending on what the goal is for the system you know you might need to look at I use more in winter because I run the heater all the time and summer I do anything because I love the heat. Or it could be ver reverse.

So I run the air con all the time because I can’t stand the heat. Winter I love the cold. Yeah. You know, so generally most of the times you want to be sizing for that peak demand.

So you’re covered through those other sides. Mhm. Um if you’re just looking at production, production in winter is always less, isn’t it? Yeah.

So a lot of time if you size for um peak usage in summer when the production is less you’re going to almost have oversiz in panels to charge that battery and everything as well aren’t you in production’s less. Most definitely. So um you reckon you your usage trends change when summer winter? Absolutely.

Yep. In the summer time I’m never at home. Yeah. That’s that yeah that that was going to be one thing I mentioned was yeah just the people act differently during summer and winter as well.

It’s not even just about usage. Yeah. People are out of the house going out for dinner. You’re out later in the afternoon cuz it’s not like poor get home on the rooftop pool.

Yeah, that’s it. Yeah. Yeah. 100%. Um yeah, even like it gets darker later.

So yeah, absolutely. It’s massive. It is is probably a massive thing to look out for. Back to the property max demand side of things.

Um, do you understand where we’re sort of going with that? The Yeah. So, Yep. Is there anything you can think of that like, let’s just say you’re getting solar and battery now?

Yes. Yep. What’s something that you’ve had on your mind that you’re going to purchase that’s going to use electricity within the next 6 months? Maybe a brand new air conditioner.

Maybe one needs to be replaced or it’s a little bit older or doesn’t fit the house. or some people, which a lot of people don’t think of, like, oh, I’m gonna upgrade my dishwasher to one that’s got a timer on it, washing machine, clothes dryer. I’m going to get a close dryer cuz I got solar and battery now. I’ve got one induction cooktop. There you go.

There you go. Perfect. Just all all those little things. Um, they’re things that people can have a think about.

Oh, definitely. I better better tell the bloke that’s sizing up me solar and battery. I’m I’m thinking about changing all of these things when I get this installed purely because that’s that’s going to really increase the size I need. Definitely.

Even the aircons as well. Like I did touch on the ducts earlier, but not everyone’s going to get a ducted, are they? No. It might be in a a small twotory townhouse or whatever where you the duct is not going to work and it might be split systems everywhere.

Yeah. Secondhand bloody window rattler from the recycle center. um they all draw a lot a lot of power and they draw it differently. You know, you put say a 10 kW ducted if you can in the house, it’s going to be more efficient than running, you know, all 2.5 kW split systems, isn’t it? Yeah, definitely.

Offgrid and uh APS backup requirements. Actually, probably one of the biggest benefits of going battery these days. Depends on where you live. Some people will get a lot of power outages because the the network’s just not suitable or could be weather conditions and so on.

Yeah, it was actually quite well not funny but around Christmas time like cuz we we only just started up the end of last year. A lot of the calls we were making everyone was concern was they wanted backup power so their Christmas cooking and food didn’t go didn’t get spoiled if the power went out. Yeah, that’s largely because of event that did happen and everybody lost power and this none of this technology was around then unfortunately the battery and inverter technology that was around when that event did occur people capitalized down on that and it wasn’t it wasn’t good enough offgrid or EPS backup and everybody thought they were getting what they were like what they wanted which was the off-grid support or EPS backup but they didn’t like they could have gotten one power circuit one light circuit the whole backup things. Another I guess it’s another one of those things that you get a lot of the JV hi-fi people um selling as get it cuz it’s got it.

Yeah. But then they don’t actually understand the difference in what the battery can provide um whether it actually has full home backup which is generally full home. Whereas obviously majority of the batteries on the market are only partial, aren’t they? Yeah. which we had we did uh have a discussion with a certain someone about that um that we didn’t agree with on that on that front and the way it’s worded uh which came back as apparently full home backup only has to be 75% of the capability or something like that.

Ah okay. So we get something technical. It’s kind of like those warranties will guarantee you this but then by the time you go through the fine print and don’t do everything there’s not a chance of getting it. That’s it.

What is it? Yeah. we’ll pay your power bill. Like if you if you get a power bill in the next bloody or in the lifetime of your system, we’ll pay for it. But if there’s all this criteria right here that you’ve got to meet, all the fine print.

Yeah. And if you touch on one of those fine print things, but it’s not only in solar, right? It’s it’s just a marketing tactic that a lot of people use will guarantee this guarantee because people hear guarantee. They’re like, I’ll go with this.

There’s just that many conditions that you’re never going to be able to claim it. No, definitely not calling out that sort of I like and that’s that’s like that um that reel I sent you from from another company that we like quite a lot. Um that that was funny. And yeah, they’re doing exactly that.

They’re calling out the sleazy salesman at the front door. funny. Yeah, it’s good. I love that We love a good do skits. Um yeah, but yeah, I picked up on that.

No, but the full home backup and partial. Do you want to give a bit of a rundown for people that are trying to understand it? I guess they’re listening or watching whichever wherever they’re seeing us. Um, I mean, I understand it, but let’s just break it all down.

You understand? You understand all that? That’s the question that I was going to ask next is to break that down so people understand. I know a little bit about it, but I’d love to learn more.

So, let’s unpack it. So yeah, the obviously my understanding of it and we only push to sell systems that will have it um because I believe if the if the technology is there in the market at the moment, the customer should get whatever the top-notch is. Well, hate to interrupt, but on that again as well before you dive in, yeah, the cost between the having the partial and the full home with the system we use is it’s negligible. It’s like, so why not just you’re spending all that money, just get the full home backup.

Y and we we were sort of weighing up that right at the get-go as well when we did first start off. And we were honestly we we love GoodWe. We stick with GoodWe no matter what. But we were trying to weigh up whether was like there was a way we could do like an A-grade system and a B-grade system.

And the the cost was next to nothing. like the cost difference in what we were able to provide with an A grade and a B-grade. It was absolutely nothing. Yeah. Why not just offer A-grade only and an A-grade service?

Yeah. But why do people need to be offered a B-grade when the A-grade’s affordable? Yeah. So the the offgrid off-grid backup style thing that the ESA offers is a full off-grid backup.

So in a in a power outage scenario, as long as obviously you’re solving your system size correctly, it’s under 4 milliseconds that if you lose main’s grid power that you’ll switch in the battery power uh feeding your house. So everything your house is running on right now with the grid Yeah. will continue to run if the grid goes down. Yeah, definitely. From the battery.

From the battery. Yep. Yeah. Uh so yeah, that that will So what happens if the battery goes gets used up.

The battery gets used up. Then you’ve got no power just like you did before. How do you prevent the battery getting used up? Uh monitor your your usage.

Uh yeah, just just be smart with your power and put solar panels on the roof. I guess it comes back to being sized properly, doesn’t it? Yeah. Oh, yeah.

That’s it. Yeah. Exactly. Being sized correctly.

Massive size correctly. It should be sized that in that event that you know your house is going to continue to run. About the only time it may not be enough panels on the roof is the physical infrastructure. In other words, the house and the roof cannot fit enough panels to size it to that size.

You know, that’d be the only time. And then that’s 100% when it’s like you’ve got the full home backup, but you know, maybe monitor your usage like you’re saying. Yeah, definitely. Yeah.

Just don’t be running your air con flat sick when when the power outage is there. And then obviously those in comparison systems that we’re talking about, they they only offer partial backup. And people will still call it off-grid backup because in in a sales note, if you’re looking at it and it says off-grid backup, you need to ask them what that exactly means. Yeah.

Because off-grid backup could be it is off-grid backup. It’s only for one circuit. Um some only allow 16 amps of off-grid backup. Some allow 21.

So you could be expecting, you know, the power goes out, you’re going to still have nice cold beer in your beer fridge out out the back on the patio. I I will. They’ve been sold they’ve been sold the full home backup or, you know, backup without getting explained what it is. And on install day, they’re going to wire it up to the essentials, aren’t they?

Yeah, 100%. So it might be your fridge in the kitchen. Yeah. Yeah.

Um and some lights and maybe something a couple other essentials that you have, isn’t it? Yeah, that’s it. Definitely people have to look into or when they’re getting quoted, whether it’s actually off-grid or whether it’s uh just partial partial backup. So on on the whole offgrid side, and this is another reason why I actually like the good.

There’s lots of reasons why we use the GoodWe One. Um, and look, it can be done with other systems, but GoodWe, you know, you can oversize the panels by 200% to the inverter. Yeah. What’s that for?

Uh, so for 200% oversize, uh, it used to be 1.33. It’s 200% oversized now to be able to allow that extra amount of panels in the, uh, on that system to be able to charge the battery as well as your usage 100%. During the daytime, if you’re using X amount of power, you’ve now got extra 67% of solar panels there or solar power available on that uh inverter to be able to charge your batteries at the same time as you’re still using it and hopefully feed some back to the grid, which was always the the aim. But I like to look at it too like we’ve t we talked about shade a lot in other episodes or even in this one is at the start like clouds are shading the panels, aren’t they?

So every shade if you’re going to have a power outage that’s usually causing some but you know you get the power outage you go into backup mode those panels are going to charge the battery during the day you’re going to use the battery at night and the system’s just going to keep running itself isn’t it? But with that 200% over, if it is overcast and rainy during this time, well, you do have all that excess power, like you say, to charge that battery to make sure it’s good and ready at night. Yeah. 100%. Um, and that’s where I actually, you know, we we spoke about it before in other episodes about how they dropped the battery rebate because it was getting chewed up because everyone was putting on systems that were too big.

I actually believe everyone’s now actually going to get undersized systems by people that aren’t actually designing properly and they’re just chasing the maximum rebate they can claim and selling them whatever they can at the easiest sale. Okay. Cuz those ones that are only going to get a, you know, 14 kilowatt battery now and that’s probably why everyone’s searching the 13.5. True.

The most rebate and they’re getting sold that and they’re thinking they’re getting the best deal and the best return on investment and everything like that. Um if their goal was to have full home backup and wipe out their bill as much as they can, chances are they’re probably going to get jack out of it. Yeah. Um what happened recently?

You might know this one, Del. What happened recently in New South Wales? What did they bring out? Oh god, I thought we were talking rugby there for a second.

Well, oh, we know who won the origin. What did they bring out? Uh the uh Oh, yeah. I know.

They won the 0% entry. That’s right. Yeah. Yes.

So, that’s exactly like moves into what Jayce is saying. They they’ve lowered the rebate uh to stop people getting oversized systems, but now essentially they’re forcing people into undersized systems. Y um I I don’t know, it could be completely innocent. They’re just silly buggers sitting me on a computer screen trying to fudge their numbers and make sure it lasts and they look good at the next election.

But my firm belief is they want people to be reliance on the grid. Yeah. like the whole NETCC Um, I don’t I don’t believe in it. Um, if you are listening, we are applying and we will become a member of the NETCC because we have to, but yeah, don’t believe in it. So, don’t So, to be a part of that, I think it’s all just a big a bit bit of a money grab to be honest.

Yeah, it’s just a it’s just a badge for people to hide behind. The reality is we actually follow their code more than the people that actually have the badge. And it’s just a sales code. Yeah, that’s all it is.

That’s if anyone doesn’t actually understand what the NETCC badge is, it’s a badge to say that as a business, we are following a a retailer’s code of conduct, which means we’re not going to operate and do all the JV high sleazy salesman tactics. Okay. And the reality is we don’t have that badge. Yeah, but we actually follow that code more than majority of the people that actually have it.

And a lot of them just pay the pay the yearly subscription, which isn’t cheap. Yeah. To have this badge to say, “Hey, look at me. I’m doing this.” When reality is they’re not.

Yeah. Definitely. Yeah. But the 0% interest loans are the only reason we’re going to get the badge so we can offer that.

And do it right. Yeah. And do it correctly. hopefully give the customer or only sell it to the ones that uh can actually think back to what you’re you sort of saying about those 0% loans. So this is the New South Wales 0% loan because it’s only New South Wales state level government cuz the battery rebate and solar rebate’s federal so every state gets it.

Yeah. So New South Wales government’s introduced that 0% loan and it’s only up to $15,000. So whatever you buy has got to be $15,000 below. Yes.

Y we’ve been talking about the prices of systems and generally you’re going to be 20,000 or 15 20,000 30,000 above. So look, it is going to help I guess say pensioners and boomers that are retired and their usage is getting lower and they’re about the only people that generally would only need up to a 14 kilowatt hour battery. Yeah. Okay. anyone other than that, a family with kids growing, uh, their usage is going to grow and it service doesn’t serve them at all.

Yeah. Yeah. They bring up uh just like a quick add a glance like between let’s say the GB ESA and then the Sungrow SPH um just like differences. Uh so for like the whole home offgrid backup side of things, uh GoodWe is a whole home backup built right in.

Um and the Sungrow SBH series is a selected circuit EPS backup standard. Uh the switchover speed is under four milliseconds for the GoodWe ESA. Um round about 10 milliseconds for the SPH. Uh reason I brought that up.

So one will drop your Wi-Fi out, the other one won’t. Yeah. Right. And that matters when you work at home. 100%.

Definitely does. Yeah. Yeah. Just a little bit more of a brag about the ESA.

Yeah. So, the most probably the closest thing on the market to the GoodWe ESA is the Sig Energy, isn’t it? And we spoke about that in another episode. It’s quite a good system, quite a good battery, but even that’s not the all in one full home backup, is it?

No. So, it’s got They probably will bring something out. Yeah. So, it’s still got a full home backup, but yeah, for the for the off-grid capability, you need the gateway installed as well. um which everybody does but however it’s still not an all-in-one system.

They are bringing one out which look out GoodWe. You’re going to have to drop your prices. Yeah. So when you say you need another gateway is that more hardware they got to install around the house or is that just a software gateway?

What is it? Just so everyone understands. Yeah. So what it reminds me of is it’s just like an inverter.

Like it’s it’s the size, it’s the look, it’s the everything just like a a sol normal solar inverter and then you’ve got a separate stack of batteries somewhere. That’s what that’s what we’re trying to run away from. Yeah. So, it’s just more hardware on a wall somewhere around your home.

Yeah. Yeah. More cables going to a spot, but Yeah. Awesome.

The all-in-one will be quite nice. Um or micro inverter systems. Uh the other one people uh people got very I feel like they did have their place in the market, but micro inverter systems I believe were for uh multi-roof face where somebody had bugger roof space on the roof. Um you couldn’t piece together a proper string.

Yeah. Exactly. So you got a you just got a brick brack buddy panels all over the roof and like you can just line them all in together. Oh, I mean they are another benefit probably would be for highly shaded areas.

Yeah, definitely. But again, it’s not going to make them produce in the shade, is it? No, won’t make them produce in the shade, but at least each one as the shade goes over can work individually and like not to get mixed up with an optimizer, which a lot of people will tell you, but the micro inverter all operated independently. the the optimizer will drop it out of the string to avoid it from dragging the rest down. Yeah.

Uh bloody ripper. So, yeah, realistically, if you are getting a solar system designed, hopefully by Source Energy Group, make sure these are questions you ask. Get in touch with your your sales company, with your with your subcontractor, with your electrician. Anyone could be selling you this.

Make sure you ask the questions. Go back and listen to our other podcasts. uh cuz very informative and you can’t make design mistakes. You’ll pay twice. So, how many panels per string?

Okay. On your inverter, you know, what’s the demand on your property? Have they looked at your usage trends? Are you going for full home backup or you just happy with the partial home backup?

Do you need optimizers? Uh are they offering you optimizers, micro inverters, or just the standard inverter? And your choice of company is going to be the major one. Get in contact with Delphy. give her a call.

She’ll hook she’ll hook you up with one of our team um if you want to find out this information and get your system designed properly. If you have any other questions that we haven’t covered here in this one, we’ve actually just done an episode of it’s a Q&A episode where we go through uh I think it’s about 14 questions that been getting asked online and through our support. Jump back if