OFF GRID POWER
When is going off grid the only option? (see item 10.)
I will answer what is required for an off grid power installation.
Follow the frequently asked questions and answers. (FAQ)
1. DOING YOUR OWN ELECTRICAL WORK.
Any installers, who installs solar system and connects this to the public electricity grid, needs to be a licensed electrician plus he also needs to have a DC license in addition. When the installation is finished this electrician needs to sign off on a form, stating his license numbers.
Doing DIY electrical work is illegal. The rules state you need to be qualified or licensed, without really stating what qualified means.
But with all those things, if you do a completely independent off grid installation, there is no sign off form needed. So who is qualified then?
If you have received training and instructions on what to do, and have a fall back possibility to ask questions, are you now qualified?
2. WHAT ARE WE TALKING ABOUT, WHEN WE MENTION A GRID.
The dictionaries say a grid is a series of parallel lines or sometimes crossed lines. In the electric sphere the lines are wires criss-crossing the country side, to distribute electricity from the generator plant to the end user.
So when we have the generator being a power station and you are being charged for the electricity you use, then we have a public grid.
If you are both the power generator and the end user, then you have a private grid. That is also referred to as Off-grid, because you are not on the public grid.
The installation rules are there to protect the generator, any installer and the end user and maybe also the environment. Things have to be safe!
It is my belief, that there are such things as the protection of the individuals freedom. This might mean, if an individual wants to build or create something, he should be allowed to do that. however, provided he does not interfere with, or become a burden on society or public facilities.
3. LET ME EXPLAIN HOW AN OFF-GRID PROJECT WORKS.
- The bulk of the equipment is made overseas and needs to be imported. Sometimes an agent does that, or the company has a subsidiary in Australia.
- Then we have a wholesaler, who distributes to contractors, installers or retailers.
Because this solar business is virtually a closed industry, there is very little emphasis on competition.
If your power plant has to be connected to the public grid, the job has to be signed off by a licensed electrician, who also needs to have a DC license.
I managed to get a resale account with some large wholesalers of this type of equipment, and I can supply this at reasonable prices, but only for off grid installations. This means an installation that does not connect to the public grid.
- The recommended resale price ex the wholesaler has a 100% markup. And all the contractor has to do is order the equipment and get it delivered. They usually do not have stock on hand.
- Then there is a an installation cost for onsite work, which could be between $4000 and $8000.
- Also please note to install an inverter to the wall is not a one man task, because some of them weigh up to 65kg.
When I supply the equipment, I supply it with instructions and costed at a 20% markup, rather then 100%, but you have to do your own installation. But I can only do that for a completely OFF-GRID project.
4. SOLAR PANELS.
With Solar panels there are tier 1, 2 and 3 suppliers. The tier 1 are large companies with their own research facilities. And things get progressively less reliable, with tier 3, being risky.
I stay with the tier 1 like Trina and Jinko. Now I must also say, that the first lot of panels were only 330W per panel, now they sell 450W. They are also getting thinner, and sometimes larger, to fit more cells.
You need to be careful to not buy too many solar panels. Their total output power and voltage need to match the capacity of the inverter. That type of inverter is discussed on my point 5.
Continue with the next column to the right, which shows a picture of my solar panel setup.
5. A GRID TIED INVERTER or Solar inverter.
This inverter converts the DC voltage from the solar panels into AC. The word grid tied means that this inverter will only do its job, if it can see an active AC grid at its output terminals. The trick is now that the AC power it creates must exactly follow the phase and voltage of the active grid it sees. If there is no grid at the terminal, the inverter shuts down.
Continuing what you need for a private grid.
6. A BANK OF BATTERIES.
In a second location the bank of batteries is yet another source of electric energy. Once more this is a DC source. The voltage can vary from 12V, 24V, 36V and 52V etc. The energy in the batteries cannot be used as is. There are several types of batteries.
- I have chosen to go with the more expensive Lithium Ion batteries. They should last 10 years or more and they can be drawn down to 10-20% of the full charge. They are a tricky device, and can only be charged by dedicated devices.
- The alternative is 12V or 24V lead acid batteries. They are a lot cheaper, but they only last 3 to 5 years. In addition they can only be drawn down to 50% of their full charge.
- The life of a battery is not determined by years, but it often works out that way. More important factors are:
- The number of charges and discharges.
- The regular depth of discharge.
- Sudden very heavy loads on the battery and how often do they occur.
- Exposing batteries to extreme temperatures.
- The regular magnitude of the charging current.
- All these things add up over time and some batteries handle it well and others don’t.
7. A BATTERY MANAGEMENT INVERTER.
This inverter takes the DC energy from the battery and creates an AC grid of 230 Volts. It also controls the voltage and the phase of the grid. There is a second task, which is checking the state of charge of the batteries. Let’s look at the control actions of the inverter with respect to the battery health:
- It can give a signal that the batteries need charging. This inverter has 2 inlets, one with DC from the batteries and one connected to a standby generator. A generator equipped with auto start can be turned on and off by the inverter. I am not using that feature.
- When the State of Charge (SOC) reaches the lowest setpoint, it will shutdown the complete grid, including the solar panels.
- When the SOC reaches 99%, my inverters will change the grid frequency slightly (1-2 Hz) for a few seconds. The solar inverter picks that up and shuts down the solar panels.
- When the SOC reaches 100%, the inverter will stop drawing charge current from whatever device is connected, either solar panels or generator or another grid. (As could be the situation in my installation.)
8. HOW DOES THE INVERTER MANAGE THE GENERATOR AND BATTERIES?
Most battery manager inverters have a relay that can switch on a generator when the stage of charge (SOC) of the batteries is below a setpoint.
The software that comes with the inverter can produce a continuous chart of the batteries SOC. Monitoring this chart allows the grid owner to plan his load, when to run certain operations, or not, and when to charge and for how long. Most people elect to operate the generator manually when needed, because that power is expensive.
9. LAST, BUT NOT LEAST, EVERY INSTALLATION NEEDS A SWITCHBOARD. Plus lots of cables!
A switchboard controls which circuits are on and each circuit also has a residual current devices for safety. The second board on the right monitors every one of my 14 end circuits and also my 6 sources. Because of the incompatibility of the batteries, there are some 30 relays behind the switchboard panel, to prevent mixing out-of-phase power sources (as that will create big sparks). (The relays work as lock-outs.)
But don’t worry, most people don’t need to go to this extreme.
But operating in conjunction with the inverter’s SOC chart and the AMP reading drawn by certain circuits you can make well informed choices.
Continue with the column to the right, which starts with discussion item 10.
10. When is off grid the only option?
You may be keen to go off grid, but there are some serious considerations. If there is no power at your location, then going off grid is almost the only option. Bringing power via new transmission lines to a spot is extremely expensive. My neighbour spent $80,000 to bring the power to his home, yet I could have built 2 or 3 off-grid systems for that price, because of his low power consumption. Mind you a friend was quoted $120,000 (for 5km from the main road), but he also went off-grid.
11. Here is a story, about a closed industry.
What happens in Australia!
- When the first battery/inverter system was launched it did cost about AU$12000. The same unit in the USA cost US$3000, converted AU$4000. Now we have to add some importing costs plus a moderate margin for the importer, let’s say $6000. That raises the question why is the Australian retail price two times the retail price in the USA? And a similar story about the incinerating toilet. (US$3500 to AU$6000.)
12. YET, I NEED TO GIVE SOME WARNINGS ABOUT GOING OFF GRID.
- Do not think that when you go off-grid, you will automatically save on your electricity cost, because that is not true at this point in time. The kWh cost is the same if not more. By investing in off grid power you have basically paid for your power bills in advance. But in 10, 15 maybe 20 years you will have to replace all this equipment, but now at a higher $value. {However if energy prices keep going up, you might still be on the winning side.}
- If you think that running on off grid is a set and forget, once more not true. You need to monitor things daily.
- And then if there is a breakdown, who do you call? NOBODY. You are the trouble shooter, repair man and spare parts manager.
- Please do not think you can operate an off-grid system without a generator. When it rains the solar panels have almost no output. (mine fall from 18 Amps to 1-2 Amp.)
- You might say I buy more batteries, but they are the expensive part of the system. Then choose more solar panels, but that is of no use. My solar panels have the batteries full by lunchtime in sunny days, but I struggle after 1 or 2 days solid rain.
- Let me explain the cost of generator electricity. The generator uses about 5L of petrol per 1.5 hours. At 15 Amps (65% of its capabilities) the generator gives 3.5kW/hr. So in 1.5 hours that is 5.3kWhr. The fuel cost for that time is $12. So, the power cost is (12/5.3)=$2.30 per kWh. That is almost 5 times higher than current public grid price. NOT VERY DESIRABLE. Mind the actual cost is determined by the fuel type, its price and the make, capacity and age of the generator.
OK, am I trying to talk you out of it? No, I am trying to make sure that you enter this phase with your eyes wide open, and there will be no false expectations! I can teach you about electricity, safe practices, and wiring methods, and prepare you to do the work yourself.
13. My Ebook about “working with electricity”.
I have written an Essay (or Ebook) “Working with electricty” (and it also deals with electronic components), under the category engineering. This essay is available from my shop. It handles mostly what is there and what the components do or sometimes how they work. There is also a section about wiring 230V circuits plus the safety aspects. I also spend some time on what electricity can do to the human body.
Electricity is dangerous, because it acts without warning.
If things are warm (or Hot), you can feel that and you can take precautions. Electricity does not have that feature. When you notice anything, the destructive process is already happening and it is often too late already.
Do you want to check my section about comfortable and very inexpensive shipping container living.
And you really cannot ignore my section about water usage, collection and recycling. This can be of benefit even if you are not moving off grid.
