“Here’s to it, and to it again. If you ever get to it to do it, and don’t do it,
may you never get to it to do it again.”
I’m 65. It’s unlikely during my lifetime I’ll get back the money I’ve spent this year going off-grid.
Due to saving over $3000 a year I have got back much more than the $48,000 I spent going partly off-grid in 1996 (19 years x $3000 = $57,000).
But I’m confident that the sale value of my house (The Sustainable House), and other homeowners with off-grid features, whether just energy efficient appliances or such, is higher, too.
The running costs, or “liveability” of a house, is now figuring more strongly in both the minds and the pockets of house owners, buyers and the real estate industry.
Liveability is the key to higher prices and faster selling times, according to Cecille Weldon of the Centre for Liveability Real Estate. The centre is solely focused on training and promoting real estate agents to sell sustainable housing.
Cecille says there are over 400 real estate agents specially trained to sell houses with sustainable items. She says the agents are now advocates who can sell sustainability features in the sale price and cut down the time to sell. For a list of the real estate agents go here.
This Burr is about the costs I’ve paid to go off-grid for electricity, along with costs for some other off-grid products and electricity use rates that apply to related projects.
The cost of going off-grid is directly affected by two things:
- the amount of electricity used through the year – the higher the use, the higher the cost
- the amount of sunlight which can be harvested at the site – the more sunlight, the lower the cost
Using very rough estimates based on projects I’m consulting on for consumers and businesses, and without doing a complete survey of all products on the Australian market now, the relationship between the amount of daily electricity use and system cost is in this range:
Daily average electricity use Purchase cost (panels, inverter, batteries)
5 – 7 kWh $15,000 to $35,000 – save ~ 4-10 tonnes air pollution
10 – 15 kWh $25,000 to $55,000 – save ~ 8-20 tonnes air pollution
These costs will bring an end to your electricity bills but they will also lose any savings you’re achieving from feed in tariffs and the savings you make by using your own solar electricity, which is not reflected in your bill (and which most people forget to consider.)
I’ve been working in the off-grid market and observing prices since I installed my solar grid-connected system in 1996. This year I’ve seen the costs of going off grid decline more rapidly than the decline of the price for solar panels; my rough estimate is battery prices in Australia this year have reduced by about 5 per cent with about 15 products now competing in the market and more coming.
There’s also some delightful commercial initiatives showing up in the Australian market with new energy companies and products.
Enova Energy, for instance is committing to paying higher prices for buying back solar power.
A new company, Allgrid Energy, claims it will go to market selling battery and inverter systems for less than $10,000.
And with the Adelaide City council offering $5000 rebates for battery systems there’s also leadership being shown in the public sector.
Here are the details of comparative costs between different size solar arrays.
The Sustainable House solar system costs and production analysis
|1996||March 2015||August 2015|
|Cost of panels (including inverter cost and installation fees)||$26,000
18 panels x 120W
6 panels x 327W
6 panels x 260W
|Cost of batteries and storage system||—||$17,800
Alpha ESS storage system and batteries with 8kWh storage(1.5 days supply with no sun)
Battery with 2kWh storage (total of 10kwh storage; 2 days supply with no sun)
Selling energy back to the grid
One-time renewable energy credits
One-time renewable energy credits
To disconnect from grid
|Total cost per kW of power production||$11,820/kW solar power||$4,600/kW solar power||$2,430/kW solar power|
|Total cost per kWh of energy storage||—||$2,225/kWh energy storage||$1,500/kWh energy storage|
Note: cost of panels in August 2015 were significantly lower than in March 2015 because the size of panels were lower but also because of falling prices in the market.
Expected panel production
Since the Sustainable House began producing solar power, there have been three major installations or upgrades. Below is a summary of the three installations and the total system capacity after each one:
|Date||Installations and removals||Total capacity|
|1996||8 x 120W panels installed||16kW total|
||40kW total capacity|
||52kW total capacity|
We can estimate the average daily production by month for each system and then compare those values to what the different monitoring systems report.
Analysing the panel production before and after: the August 2015 solar system upgrade
The solar production analysis compares the panel production data reported by the available systems on 2 July 2015 to 6 July 2015 with the values reported on 12 August 2015 to 17 August 2015.
The upgrade to the solar system (six additional panels and 2kWh in additional storage) occurred on 5 August 2015.
Note: Before the system upgrade, Tigo values only reflect the solar production from the six 327W panels. After the system upgrade, Tigo values reflect the solar production from the six 327W panels and the six 260W panels.
- The Alpha values reflect the solar production of the entire panel system both before and after the system upgrade.
- As shown in the diagram on page 1, Tigo reports production at the panels while Alpha reports the power received at the system after wiring losses have occurred.
- Given our expected production values for July, the Alpha system is reporting daily production to be 1kWh less that we expected: 6.6kWh/day reported versus 7.6kWh/day expected production.
- Given our expected production values for the new panels in July, the Tigo system is reporting daily production of 0.5kWh less than we expected: 3.9kWh/day reported versus 4.4kWh/day expected production.
- Given our expected production values for August, the Alpha system is reporting daily production to be 2.4kWh/day less that we expected: 7.2kWh/day reported versus 9.6kWh/day expected production.
- Given our expected production values for the new panels in August, the Tigo system is reporting daily production of 1.5kWh less than we expected: 8.1kWh/day reported versus 9.6kWh/day expected production.
The expected values we’re using to compare to the reported production values are just estimates, and it’s not surprising that the actual production values are a bit lower than the expected estimates.
However, what does raise concern is the fact that the Alpha system is showing lower production values than Tigo. A likely explanation for this can be seen because the Alpha system is reporting production values after cable losses and Tigo is reporting production values at the panels.
If this is the case, it would seem that the system is losing roughly 1kWh per day due to inefficiencies in wiring transfers and conversion between DC and AC.
Further analysis needs to be conducted to confirm that this discrepancy is indeed due to wiring losses and determine if and how these losses can be reduced.
Analysing energy consumption before and after the August 2015 upgrade
This section is a technical analysis undertaken in conjunction with environmental engineer Marianna Verlage.
Like the analysis for solar panel production, the consumption data compares the usage reported by the available systems on 2 July 2015 to 15 July 2015 with the values reported on 12 August 2015 to 17 August 2015.
There is a discrepancy of about 1kWh/day between Alpha and the other reporting systems for energy consumption. However, unlike the differences observed in the solar production section, this discrepancy points more toward a possible calibration issue with Alpha as opposed to differences in where the energy is measured.
It is important to first acknowledge that the Efergy and Wattwatchers systems are reporting consumption values taken at the meter box which should represent the energy used by the house. The Alpha system however, is between the meter box and solar panels (see solar system diagram) and is not only reporting the energy used by the house but is also measuring the energy consumed by the storage system.
When only this information is taken into account, it would suggest that Alpha’s larger consumption values by roughly 1kWh/day represent the energy required to run the storage system. However, the Alpha system claims a <2 W consumption and an inverter efficiency of 97 per cent (for every kWh DC going in we should get 0.97 kWh AC coming out), so if these numbers are correct these shouldn’t be the sources of our losses. The battery efficiency is another possible source of power losses, and we will be looking into their efficiency further.
The reason we believe the Alpha system may not be calibrated or may have some software issues is because of the base load it reports.
The Alpha system shows an average base load for the house to be 0.25kW (it is important to note that to be conservative, we took the single lowest value reported by Alpha during the 12am-6am timeframe for each day, so the actual baseload Alpha reports is even higher than this). If we extrapolate just the base load out for the entire day, this results in a daily usage of 6kWh, which is higher than the total daily usage that Alpha reports.
Because of this uncertainty about the accuracy of the Alpha system, we cannot confidently conclude what the house’s average daily consumption is including the power used by the storage system. However, we can be fairly confident (given the values reported by both Efergy and Wattwatchers) that the energy consumption inside the house is between 4-5kWh per day with a base load of 0.85kW to 0.9kW. More research and analysis should be done to resolve the discrepancies with the Alpha system.