Tiny Power! Part 1
Updated: Jun 17, 2020
My Tiny solar power system has been in place for 3 years now and has done its job of facilitating power. When I first started I had no idea about solar power and felt like I was starting from scratch to understand it. The tiny house industry was not where it is today, and just like I had to build one if I wanted the type of tiny house I had in mind, I also had to make sense of a somewhat fragmented solar industry that was not well equipped to deal with newbies in tiny house power. At the time I found this incredibly frustrating, but in hindsight it means I know a lot more about solar power (and tiny house power in general!) now than I did before and am now best placed to troubleshoot my own power issues. And that feels good.
I started like most people do, calling solar power companies, asking about their small off-grid systems. There were only 2 companies that sold systems that were both tiny-house small and off-grid. Neither had the features I really wanted, in particular access to the data. That feature only came with larger residential size systems that plugged into the grid. Neither option came with a comprehensive user guide that would explain exactly how the whole system worked - it was really just a collection of user manuals for each component and some friendly encouragement from the sales person. You'd have thought that building in Sydney would have meant that I would have access to local providers, but the smaller providers were many hundreds of kilometres away so a site visit was not possible.
In the end I went with Aussie Off Grid (now Aussie Batteries), whose salesman enthusiastically assured me that I would not need to hire an installer, that I would be able to do it myself. It was a kit that came with a pre-wired board so he was essentially right, but his enthusiasm was not accompanied with any kind of comprehensive guide. Perhaps he figured that if I had built a tiny house, I'd be able to work the kit out. So for a total cost of around $5,500 I had a pallet of equipment delivered to me. With very few instructions.
I spent the next week unpacking the parts, trying to make sense of the bits, googling the named parts and trying to understand what I was supposed to do. I made several calls to the solar power salesman, and he continued to help as much as he could from afar. The user manual for the inverter had several schematic diagrams to indicate how you might wire your batteries for various voltages. Alas, all I did was look for the layout that looked the most like mine (ie same number of batteries and size batteries) but forgot my high school physics class that taught me the significant difference in results of wiring in series vs parallel. In effect I wired the batteries for 48v when it should have been 24v. The inverter displayed an error code and despite several attempts to understand what the error was I couldn't work it out. I got onto their salesman and then their tech support and after a few exchanged photos, it was established I had wired it incorrectly, and may have even damaged the unit in doing so. By now, I was pretty annoyed that the salesman had assured me I could d put the kit together myself, however I wired it correctly (luckily no damage was done), and the thing started producing power. That joy of having independent lights on my build replaced the irritation I felt towards the solar company.
I had decided that I wanted the solar panels separate to the house so that I could park it in the shade without impacting my ability to produce power. So I built some frames to hold the solar panels and wired them, being careful now to use my voltmeter to test that I had the wiring correct before plugging it into my inverter! The one confusing part about wiring the solar panels was that the kit came with cable and connectors and no obvious way of crimping the connectors to the cable. I googled this and worked out you needed a crimping tool but you couldn't buy them as a consumer. I ended up visiting a solar power company around the corner from where I was building with the bits and asked if they sold the crimping tool. They were kind enough to explain how you could crimp without the tool, which was clumsy but effective, and were also able to sell me a few replacement connectors I'd broken in the process.
So feeling like a complete hack, and not very confident about it, I managed to get my solar power system working. The system was promised to provide me 2-3 days autonomy but it never actually delivered on this. I think I got about 1 day autonomy (enough power in the batteries to supply me with power for a day if it was cloudy and solar panels were not producing) but that was only in the first 12 months. Now in summer I don't need additional power unless there are a few days of cloudy weather but in winter I only get power in the middle of the day from the system and need to take additional power from mains to run my air conditioner in the evenings. Why this was the case was never established. Which leads me to why my wish for data was even more important than I realised.
After 12 months (6 months building and 6 months living) I soon found out that debating whether your purchased solar system is what you asked for is a waste of time without data. Because how your solar system performs depends on how you manage it and without data, it's all conjecture. How much charge did your batteries get before solar production stopped for the day? What level did the batteries drop to during the non-solar producing part of the day? What load was put on them at what voltage level? Without the answers to these questions you are navigating blind.
Whilst I didn't understand all this at first, I knew I wanted to know at least what my battery levels were at without having to physically look at the inverter LCD display. I tried very hard to install a raspberry pi server connected to the inverter but the USB port would have nothing to do with such technology. And the data stream from the inverter was in a proprietary format meaning nothing I could do would allow me to plug it into a modern energy dashboard without some serious automated manipulation. So I bought a cheap laptop and loaded the (very difficult to find online) inverter software so that I could save the data to the laptop. I loaded TeamViewer on the laptop so I could remote into the laptop and see what was happening from the convenience of my desk inside tiny, but it was never an ideal system. For a start, after about a month's worth of data saving, the software would run so slow that it would take 10mins to just query today's data chart. Exporting the data took even longer. Maybe it was because it was on a low performance laptop, but I didn't have anything else lying around to use. Also, if the connection to my wifi dropped out I'd have to go see what was going on at the inverter anyway. It was just not the seamless experience I had hoped for.
When I contacted Aussie Off Grid to complain I wasn't getting the promised performance, their tech support staff would spend hours on the phone and on email looking over spreadsheets I had managed to pull off the inverter but to be fair, he was only get part of the story. What solar was being generated? What load was being put on the system? In the end they replaced the AGM batteries under warranty (pro-rata) but the new ones performed slightly better for 12 months before dropping back to previous performance standards. By this stage, Aussie Off Grid was now Aussie Batteries and they were sick of me. They stopped returning my calls, and required 1 week's notice to book in a telephone call with a technician who would be hours late for that call. The technical staff were helpful when I got onto them but it felt like the company had set them up for days/weeks of sorting out issues that weren't their fault and were highly difficult to diagnose and fix. Eventually the receptionist would insist there was simply no one in the office other than herself whenever I called at any time of day and I realised I would have to give up on them. That was unfair on me, but I made the decision to prioritise my sanity and move on. Data would be the way forward.
Because I was using considerable power from my landlord, I installed a power monitor between the power point and the extension lead. I used the Efergy Ego Smart Socket which has a companion app that allows me to monitor how much power I am taking through this powerpoint. Its an older style device that I put in place 2 years ago and whilst the app has been upgraded and some smart features added (like rules to turn it back on if ever turned off) I don't know that it will integrate into Apple HomeKit or the Android equivalent. Whilst the app provides historical totals, as far as I am aware I can't download historical data. It was not expensive and it's done its job, which was to enable my landlord to calculate the power I use and both parties have been happy with it.
Because the power cable plugged into my landlord is about 50m long there will be considerable losses over this connection. In order to understand my actual usage needs (to inform the next iteration of solar power) I have also installed an Energy Monitoring Kit (Efergy Hub Kit) which measures the AC mains power coming into the inverter via clamps and the AC leaving the inverter feeding my tiny house. There are still considerable losses here but the most important data is how much my tiny house is pulling. This data is available via an API feed and I can access this either via Efergy's personal dashboard, or by enabling a public dashboard using the API. If you are interested in this level of data, you can review it here.
The most power-hungry appliances I use are the air conditioner (which can run entirely off the solar panels in summer) and the fridge. You can see when these items power up and down clearly in the data. Winter is an expensive time of year for me because I need the air conditioner when there is no sun to power me, and that is a lot of the time thanks to the reduced amount of sun I get in the narrow valley I live in. Other than that I have LED lighting, a bathroom exhaust fan, kitchen range hood, laptop and an LCD computer monitor which I use for work during the day and watching movies at night. I use LPG gas for heating water and for the stove and cooktop.
The differences in mains power being pulled into the system versus what is being used to feed the tiny house are very interesting but I have not been able to establish the source of these impressive losses (other than the very long extension cable). But they do suggest that the system is not adequate for my purposes. What I can see is how much power I need to run my household so I know that I am looking for a 6.5kWh system. I also know that in winter I probably need another couple of solar panels, even though in summer 4 are plenty. I also believe that the low temperatures we get in Bright are probably sub-optimal for the AGM batteries. Either the enclosure needs to be insulated or I need to regulate the temperature. Currently they sit in an enclosed (and uninsulated) cargo trailer.
And so, armed with data and a greater understanding of solar power in general, I began the search for Tiny Power v2.