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These pages detail our attempts to minimize our eco-footprint. We have explored
See separate page for plots.
We currently are running:
There are 3 inverters involved:
There are 2 sets of batteries:
There are a number of pieces of software to assist in the management of the PV system. These are:
An associated script, /home/ajh/bin/checkSolarLog.sh, is run every 10 minutes to ensure that logSolar.py is still running, and if not, to restart it.
The original installation of 2003 was accompanied by 20x75W panels, which over the years became somewhat obsolete and inefficient. They took up valuable roof space, and given that they had paid themselves off over 15+ years, it was not a difficult decision to replace the panels. But because the system had (lead acid) batteries which were only ever used in UPS (uninterruptible power supply) mode, we decided to keep the Trace inverter and batteries as a stand-alone unit. They had been wired into the house circuitry via a separate network of power points used to run fridges and computers, and had proved effective in that mode. These batteries are no longer charged by solar panels, but instead rely on the grid and/or other inverters for charging. The UPS functionality is preserved.
This 2003 system ran well for 13 years, with an average (grid) consumption of around 20kWh/day. The solar panels generated a yearly average of around 4.6kWh/day, for a total consumption of 25kWh, less in summer, more in winter. Most of this consumption was due to running several computers 24/7 with a total load of about 1kW, accounting for half the base load.
With the remodelling of our house in 2016/7, it seemed appropriate to upgrade this system, and extend the number of panels to fill out the available capacity of the inverter. However, while I was told that this was technically feasible, a better and cheaper solution was to go for a completely independent new inverter and panels. So we installed the Fronius Primo 3kW inverter, together with 3kW of PV panels. This doubled the capacity of the old system, and served well for 5 more years, with a new average consumption of approximately 12kWh/day.
In Mar 2018 our renovated house took on new residents. Our son and daughter-in-law with their two daughters moved into the house with us. This was planned (see My Personal Page), so it was no surprise. But our services consumption has increased correspondingly. Our daily electricity usage then more than doubled to 28KWh per day, against the 12kWh/day that we had been using.
As part of the ongoing evolution of our environmentally conscious house improvement regime, we replaced our solar/gas boost hot water system in Aug 2021 with a heat pump. This had the effect of halving our gas consumption, but at the expense of electricity consumption. Our usage jumped from 28kWh/day to 43kWh/day! To be fair, this is based upon a small time period, and may not be an accurate reflection of usage. One significant aspect of this is that the hot water system uses a ring main to provide fairly instant hot water, but this comes at a cost of circulating hot water at 70 degrees around the building, with attendant heat losses, and further energy consumption.
Part of this consumption was reduced by introducing a timer to the ring main pump, which only switched the ring main on at peak demand times, i.e., early morning (for showers), lunch time (for washing up), and evening (washing up and childrens' baths). (I have not attempted to extract data to determine the quantification of this change.) A further improvement was to set the hot water heat pump to only come on in the day time, when the solar panels can be generating to supply the energy. These improvements saw our energy consumption drop to the order of 38kWh/day.
In Jul 2022 we scrapped the original 1.5kW panels (but kept the associated Trace inverter and battery as a UPS), and used the freed-up roof space to install 13.3kW of new technology solar panels, along with a 10kW inverter. This inverter was wired in parallel (with associated isolating switches) with the Fronius inverter, and thus functioned as a stand-alone, independent solar system.
Then in Aug 2022 we invested in a 5kWh battery to add to the 16kW solar system. By shifting solar power from the middle of the day to the evening, we a) reduced our grid consumption, and b) earned the full tariff on the power saved rather than feeding the excess energy back to the grid. Given that we are limited to 5c/kWH and a total of 5kWh/day from the feed-in, this is quite significant! It leaves a headroom of over 10kWh for running things like the heat pump, driers, and other intermittent heavy uses.
Indeed, it has been so successful in reducing our consumption down to about 20kWh/day that we have added 2 additional 5kWh batteries to the system. On sunny days, I believe that this will make us almost self sufficent!
This diagram shows how the three inverters sit side by side. The Trace inverter functions purely as a UPS (uninterruptible power supply), while the Fronius and SolarEdge inverters function as "normal" inverters. The Active and Neutral connections connect to the grid, while the circuits below the RCD (residual current device) feed separate UPS sockets scattered throughout the three levels of the house. Anything plugged into these sockets will have continous power in the event of a grid outage (subject to the capacity of the battery, around 5kWh).
Note that in the event of an outage, the Trace inverter automatically isolates itself from the grid (it uses an internal isolating switch, and not the shown isolating switch), thereby ensuring that there is no back-feed of power to the rest of the house wiring, and most importantly, the grid.
Note also that the shown battery (lead-acid gel cells) plays no part in the normal day-to-day solar battery operation. It is only used in the event of grid outages.
We now have three 2000 litre tanks for collecting rainwater. The 4000 litre "wootank" had to be dismantled at the start of renovations. Imagine our surprise when we found Percy the Perch flopping around in the bottom as we drained it. We thought he had died years ago. We rescued him and took him to Jells Park, where we released him into the lake there.
Unfortunately, at the moment none of the tanks are plumbed to any outlets, so overflow simply goes down the drain. Two factors limit the plumbing: a) the supply pump is currently decomissioned, and needs to be re-instated; and b) there are no vegetable gardens, toilets, or other outlets currently plumbed in.
(20210907:115435) The pump has been recommissioned, and two (20230205:175432) vegetable garden beds are now with irrigation. But the pump currently suffers from excessive leaking from its joint (more teflon tape anyone?) and urgently needs attention.
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