Environment
Quick Links
Background
These pages detail our attempts to minimize our eco-footprint.
We have explored
-
Photo-Voltaic panels
(including Uninterruptible Power Supplies)
-
Rainwater Harvesting
- Smart Heating
- Computer support for all the above
Photovoltaic Panels
Today's Generation
See separate page for plots.
Current Scenario
We currently are running:
- 36x370W REC Alpha panels, installed Jul 2022
- 12x275W Canadian Poly Panel, installed Feb 2018
Total generating capacity: 16.62 kW (inverter limited to 10kW)
There are 3 inverters involved:
- Trace SW Series 3.5kW, installed Mar 2003
- Fronius Primo 3.0kW, installed Feb 2018
- SolarEdge SE10000H Energy Hub, installed Jul 2022
Total inverter capacity: 16.5 kW
There are 2 sets of batteries:
- 12x2v Lead Acid cells, rated at 7.9 kWh
- 3x5.04kWh Alpha SMILE-B3-PLUS batteries
Total battery capacity: 23 kWh (Alpha battery inverter max 3kW)
PV Associated Software
There are a number of pieces of software to assist in the
management of the PV system. These are:
- /home/ajh/Personal/Home/Solar/python/logSolar.py
-
This runs on the reuilly computer, and logs
the current recordings of each of the Solar Edge and
Fronius systems every minute, to a file
/home/ajh/logs/solar-{date}.log, where
'date' is the current date in the format YYYYMMDD.
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.
- /home/ajh/Personal/Home/Solar/python/EnergyChart.py
-
This program is a python3 module that provides the
EnergyChart class. This class, when
instantiated with a date argument (as above), loads all
solar data associated with that date, and then provides a
number of methods and attributes for the data.
- powerGen()
-
returns the total power generated by the solar array
for the given data
- drawBattery()
-
generates a plot of all (relevant) solar system parameters
- drawEnergyChart()
-
an earlier version of drawBattery, showing only energy
generation (kWh)
- drawPowerChart
-
an earlier version of drawBattery, showing only
power generation (kW)
- drawMaxChart(reset=True,rollingLength=28)
-
a decommissioned method to show averaged maximum
energy levels over a number of days, given by
rollingLength
- totgen
- total (energy) generation in wattHours
- totload
- total load in wattHours
- totgrid
- total grid in wattHours (grid load is -ve for feedin)
- maxbatt
-
maximum battery charge for the day, as a percentage of
total capacity
- /home/ajh/bin/makeSolarFig.sh
-
This is a script that runs on the reuilly
computer every 10 minutes, and calls the
EnergyChart.drawBattery method to plot key
parameters of the whole PV system. The result of this
plot is stored in a file
/home/ajh/public_html/images/solar/{date}.jpg
(where 'date' is as above). The script also uploads the
plot to public facing servers.
- /home/ajh/public_html/cgi-bin/solar.py
-
This code is run by every web server to display the
current plot generated by the previous item. It also has
buttons to navigate through displays of previous dates.
Comments on the History of the System
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.
Changes post 2018
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.
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Home Photo Voltaics
Whirlpool Discussion
Current Rainwater Harvesting
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.
