The SolarEdge inverter I have (SE5000 model for those playing at home) feeds back data to their HQ, which I can access through a web portal. At the moment I’m just taking screenshots to log interesting events, and provide feedback to everyone in the chain.
As you can see, its great from a consumer perspective to understand your power usage at-a-glance, as well as the Powerwall and panels data. So I know this week how much I’ve exported, used on my own needs, and what I had to take from the grid.
You can see that 25th Feb was the hot Thursday, with temperatures reaching 41oC in the shade. The ability of our family to tolerate that kind of heat is not pronounced, so the air conditioner goes on.
The big red spikes above the “4k” line represent our ducted air conditioner going on. Yep, its a hungry beast. Generally speaking, it seems to kick off around 5kW to run as an absolute minimum, and generally goes around 6kW, depending on the ambient (room) temperature versus the thermostat.
One thing I didn’t fully understand when I got my system installed was the power parameters. I have a 5kW inverter, that means the system can move 5kW from the panels and Powerwall as a maximum.
So, for example, if the panels are blazing and the Powerwall is full, but I need to run the ducted air, it is going to pull a maximum of 5kW from my panels and battery combined, and then go to the grid for the rest.
Yeah, bummer, right? Unfortunately, the house came with this A/C so there isn’t much I can do about it at this point, beyond mitigating my use of it and setting my house up a little better. More on that point in a later post, when I get more time to think about it.
So, back to reviewing the data, and let’s continue by just looking at the solar generation side of things – and to make it interesting, let’s drill down on the days leading up to the full moon (yes, the portal has a drag-zoom setup – its pretty cool).
So we have some nice, parabolic curves representing power generation during the day. The peak is generally around 2PM each day (keep in mind we’re in DST here) and quite often hits in around the 4kW mark. However, I’ve seen individual readouts above this. I guess the graphing software tries to smooth curves as often as possible.
This isn’t the best bit though – notice the little squiggles happening around midnight on each day? I’m told by the installer that customers have reported moonlight triggering the panels, and I guess, being photo-voltaic in nature they respond to any light bright enough. Yep, that’s right:
Here is a zoomed-in version from the night of the 24th Feb through to about dawn on the 25th, showing the fluctuations. Not much graph smoothing here!
I’m kind of geeking out over this, in case you hadn’t guessed. Sure it isn’t a lot of actual power (up to 70 watts), but you must admit, that is pretty cool.
But going back to the top chart for a minute, you can see from the 25th onward a lot of red readout in the low-levels, meaning the Powerwall has ceased covering “Self Consumption”. The day after was cloudy, so little opportunity to replenish the levels.
After some awesome sunlight today with a nice cool breeze (no air con!), the Powerwall is sitting around 70% to get me through tonight and beyond.
It helps that we were out today, not using much power, and having an awesome lunch at Barbuto Restaurant in Narrabeen, followed by a stint on the beach in the afternoon. Great day!
My name is John, and I had the privilege of the first Tesla Powerwall installation in Australia (maybe the world, they say). It has been a short, but very interesting journey so far, and as it continues I hope to share useful information, a bit of humour, and a hopefully less swearing than I provide in person*.
It would be remiss of me if I didn’t mention Natural Solar at this point. Chris Williams, Oliver Coleman, and the whole crew have been really helpful in putting my system together, and I’m seeing results already.
I’ve got all these grand ideas about what I want to do here, but I typed most of this up on a Thursday night, having come home from at work with little in the way of motivation after a 41oC day here in Sydney (106oF for any Americans reading).
You’ll have to forgive the absence of anything like style on this site. I am one of the least creative people you’ll meet in terms of design and UX in general. My job as a database guy is more about structure and numbers, and its a different kind of beauty…
The good news is, I know people who are fully conversant with the interwebs, and have great advice, which they will no doubt give, so this will improve over time.
I just thought it was time to get it started, and the best place to start is at the beginning.
Why did I install Tesla Powerwall?
There were many battery options out there already, but this one happened to fit my needs best, and I’ll definitely cover that in more detail in a future post.
The installation itself has been covered in a fair few outlets in the mainstream like The Australian/AFR, News Corp, Sydney Morning Herald. All of them seemed to have their own angle on Tesla Powerwall, and what its going to do for the planet, or their otherwise empty column inches that week. At least, those they’re not stealing from Huffpost or some random entertainment website…
Ultimately, there is a financial argument that underpins why I got a Tesla Powerwall (or any solar hybrid system) installed. Despite being accused of a “profligate Western middle class lifestyle” I’m by no means rich (and no steve f – if that is your real name – the pool isn’t heated). I earn above the national average, and am fortunate enough to have a smart, talented, hard-working fox of a wife who earns something similar.
Ultimately, I make no apologies for trying to enjoy my life while offsetting that with investment in renewable energy, but some people can’t be pleased.
Renewable energy investment makes up the second leg of the argument. There is a growing need for research and development into solar, wind, and other forms of power. We can’t keep burning things to make lights come on when we have, as Elon Musk said, a giant, free source of energy right up in the sky. All we need is the will to change.
The good news from my perspective, now that I’m following sites like Renew Economy and One Step Off The Grid, it is clear that this movement away from coal and oil is only accelerating, if we can get our politicians to listen for long enough.
The third part of my desire for this is sheer nerdliness. I’ve been watching Tesla for a while now, and what they’re doing is impressive under the leadership of Elon Musk. You can read about Elon Musk in a long and humorous fan perspective at Wait But Why if you don’t know much about him already.
A few people – friends, friends of friends, complete strangers – have asked me what the best solar system to buy is. “How many solar panels?” or “Should I get a battery?” and “What is that thing growing out of your head?”.
To them I say:
Everybody’s house is a little different. Everybody’s use case is a bit different. Solar isn’t just a cookie cutter approach; at least, not yet.
What I can say is that there are a few steps I’d recommend to anyone thinking about installing solar panels and/or a battery.
(Oh wait: I forgot the paragraph wailing about how slack I’ve been on the blog. That was it – well except to say I got a new job in November 2017 working in energy which is pretty rad, but keeps me way busy).
MOTIVATION FOR SOLAR
People want solar for different reasons, and from my experience of the last two years, it breaks down into a few things.
Driving down electricity bills is usually numero uno, and there is nothing wrong with that. Investing thousands into something functional like a solar PV system, you’d want to see some payback and/or stick it to “The Man” if you’re angry about whatever it is “The Man” has done.
Green feelgood is another factor. Reducing your grid needs helps save operating costs on your house, as well as your carbon footprint. You also get to understand your ability to contribute to the energy ecosystem via renewable energy.
Curiosity is a relatively new thing, particularly for modern systems with API-driven inverters. Some people (me) like to watch what is happening on their solar system at various intervals, e.g.
After that, its a question of “Do you really *need* solar?”
WHERE TO START
First place is your electricity bill.
Look at the amount you consume on a daily basis across the year. Figure out whether there are major differences between summer, autumn, spring, and winter, and I’ll bet you start to see where the pain points are in terms of running certain devices in summer (AC) or winter (heating).
As I’ve said before: most of us get our bill, have a bit of a rage about it, and then pay it and move on. You need to take the time to analyse who you are, and what you use. It will be very helpful.
Have you spoken to your electricity provider about getting the best deal? Sometimes we pay too much via “lazy tax” where we can’t be bothered even making a phone call.
Have you told your electricity provider that you’re speaking to other electricity providers about the best deal? That can be quite the motivator.
Does your electricity provider offer “green” power options? That might elevate your bill slightly, but give you part of that feelgood factor you’re after.
EFFICIENCY, EFFICIENCY, EFFICIENCY!
Next, I’m going to ask whether you’re doing everything you can to reduce your electricity consumption.
Energy Efficiency is a very much overlooked part of housing, particularly in warmer places like Australia. Building standards here aren’t so great compared to other parts of the world, and we compensate using air conditioners.
I have to say I’m guilty here of jumping into solar + storage before really checking why my bills were so high. The good news is, I’m addressing these issues now by getting awnings on my west-facing windows as well as installing downlight covers in the ceiling to reduce insulation gaps.
Perhaps it is something as simple as setting your thermostat too hot/cold, and trading money for a tiny bit of discomfort. In modern HVAC (Heating, Ventilation, Air Conditioning), each degree you set your AC up or down from 25oC can cost 10% more energy. Not cool. Or hot. Whatever.
Check all the gaps around your doors and windows. Deploy window coverings against the sun, or heavy curtains against the cold, wherever possible. Turn off the beer fridge if you’re not really using it. When you replace a device, look at the energy efficiency rating system (it can save you hundreds).
The possibilities are not endless, but they’re available, and significant.
The goal is to consume the minimum amount possible without making yourself too uncomfortable. And maybe a little discomfort isn’t such a bad thing ?
Alright, so let’s say you’ve covered the energy efficiency thing, and have a fair handle on your bills. That’s half the battle. Let’s talk about solar.
CAN YOU HANDLE THE SOLAR?
Not every roof can handle a solar PV setup. I’ve lived in a house that could not, due to a lack of appropriate space.
Start by looking at your roof space on Google Maps, and see if you have north- or west-facing roof space that might host a decent array of panels, if you’re in in the Southern Hemisphere. For those north of the equator, its south- or west-facing, obviously.
In some cases you might even want to have east-facing panels as well, due to your usage patterns. Morning people; they exist.
The more complex your roof layout, the more it is likely to cost for installation. Two storey installs can cost more in some cases. Single storey might get tricky if you’ve got multiple roof lines with minimal contiguous area.
Roofing material may also determine how difficult the install becomes, as different fixings and sealing methods are required.
If in any doubt, talk to a local installer. That’s where Google Reviews and recommendations can come in handy – find the right team and you’ll reap the benefits.
A GALAXY OF SOLAR SYSTEMS
The trouble with me recommending anything is that the internet will immediately have an opinion on it. You will read reviews that are negative about perfectly good solar PV equipment, maybe because an individual had a bad experience.
There are thousands of combinations of solar panels, inverters, and (if you require it) storage systems from which to choose. You’ve also got different metering options, which can affect how you get billed, and how you might leverage peak/offpeak power rates.
“How many panels do I get?” is a pertinent question, and my response is always that panels are cheap, so get as many as you can afford.
Remembering that in most new setups, you’re in a “net” situation i.e. the panels feed your house first, then sell any leftover energy back to the grid at a modest rate.
Trying to self-consume every last kWh you produce is a waste of time for a grid-connected system, in my opinion. You’ll end up with a smallish system that meets your needs generally, but you’ll miss a lot of the cost offset you get from feed in tariffs, and payback time will be no different, or longer.
Panels are cheap. Get as many as you can afford.
At the same time, get an inverter that will handle that load. Having 6kW of panels isn’t going to mean much if your inverter is designed for half that. I’ve got 6.5kW of panels and my inverter maxes out at 5kW, which is generally OK, but I’d like a bit more ?
In Australia, I’d recommend a minimum of 5kW of panels. A system of that type will cost you around $6000-$7000 in Australia (installed). In the USA, Trumplandian authorities will ensure it continues to be about double that.
ADDING A BATTERY
Adding storage can double (or more) the cost of a system pretty quickly.
At this point (February 2018) it will extend the payback time accordingly because lithium batteries are still coming out of the early adopter phase. It becomes a question of capital investment versus operating cost.
If you get only the solar panels, you can get payback in under 6 years.
This makes the assumption that you’re operating the system with a decent amount of thought. Move heavy loads to the middle of the day when the sun is shining and the panels are blazing. Make the most of your feed-in-tariffs, where available. Be aware of your efficiency issues, and address them.
If you do all this right, you could get payback down below 5 years, BUT you’ll still be paying an electricity bill, even if its smaller now.
Today, the battery option will take your payback up past 6 years again, and maybe as high as 8 depending on the specifics.
There is a benefit, though: your operating costs for electricity will be closer to zero than if you have solar alone. Heck, maybe you might even turn a small profit!
There are additional benefits to your battery install as well, if you have smart technology like Reposit Power attached to the system. Selling power for $1 / kWh a few times a year might not sound like much, but when your total bill is close to zero, its heading toward profit.
It can help you save money on electricity via arbitrage if you have the right metering setup. Reposit maintain a list of good installers to use in Australia, who will ensure you get the best result.
BUT HOW MUCH WILL I SAVE???
Well, I can’t really answer that, unequivocally. A lot depends on individual circumstances.
I’m saving about $2000 per year over the first two years, having made small changes to how I run my house. I continue to make these changes as I explore ways to reduce my usage.
If you’re just going to whack the system in for something cool to look at, but not change any of your habits, expect your savings to match your behaviour.