There a three major types of solar power systems that you should now about, namely they are On-grid, off-grid and Hybrid. In this article, we will explain all of these different types of solar power systems so that it becomes easier for you to choose one of them.
1. On-grid Solar
On-grid solar is also known as:
- grid-connect solar;
- grid-tie solar, and;
- grid-feed solar
This is still the most common solar system by a country mile. Ninety-five per cent of solar systems in Australia are of this type. This is a solar energy system that is linked to the grid. It has actually no batteries connected to it. The photovoltaic panels generate direct-current (DC) electricity when light hits them. Remember, it is the light from the sun that produces the electricity, not the heat. Heat minimizes the panels’ efficiency, as we’ll learn a little later.
How do photovoltaic panels create electricity from the light? The light knocks electrons about in the silicon wafers that make up the panels. Those electrons are caught by tiny wires called ‘busbars’, which are laid on the silicon. This process is called the ‘photovoltaic effect’.
The DC power is ‘direct existing’, which indicates it is a constant voltage and current. This voltage can be high: as much as 600 V in a domestic setup.
The appliances in your home don’t use DC; they use ‘alternating present’ (A/C). Air Conditioner means that the present wiggles up and down 50 times a second. The factor they utilize AC power is that, at the development of massive electrical power generation, AC was much easier to generate. Why? Because all generators were made to spin. A steam turbine utilizes steam to spin a generator. A spinning generator with no modern-day power electronic devices to smooth it naturally generates A/C as it spins around.
Likewise, AC is a lot easier to put through transformers to boost the voltage to numerous countless volts. The current can be efficiently transmitted long distances from power stations (or wind farms) to your local substation.
The whole industrialized world is set up for Air Conditioning power, so we require to transform the DC solar energy to Air Conditioner power, which in Australia is 230 V A/C, cycling at 50 times a 2nd. That DC to Air Conditioning conversion is done by the solar inverter. The solar inverter is a box of power electronics that sits on your wall. It transforms solar DC to usable AC, which is fed directly into your house’s switchboard.
From the switchboard, the solar power will initially stream into any devices in your home that is utilizing power. There will constantly be some electricity intake in a contemporary home, so whenever there is a solar generation, at least some of it will flow into your home.
The on-grid solar system has two fundamental modes of operation, which depend on just how much solar is being produced and just how much electricity your home is utilizing.
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Mode 1: Surplus solar
If there is more solar power going into your switchboard than your devices can use at any time, the excess solar electricity will just be exported to the grid.
When there is more solar than your home needs, surplus solar is exported to the grid surplus solar electrical energy export.
This excess solar energy streams through your meter recording how much power is draining. The meter counts how much kWhs head out into the grid. It keeps tally on one of the digital counters that you can scroll through on your meter’s liquid crystal screen (LCD). Your electrical power merchant (the business that costs you every quarter) will tape this count in every billing cycle (normally every three months). If you have a ‘wise meter’, they get the number over the air. If your meter is not wise, someone comes and reads it by hand. The merchant will pay you for that exported electricity.
Mode 2: Not enough solar
Suppose at any moment; you are not generating enough solar energy for your appliances to use. In that case, your switchboard imports grid electrical power to make up the deficiency.
When there is insufficient solar to power the house, the grid tops it up.
The energy from the grid in circulations through the meter too. The meter records just how much grid energy you import so you can be charged for it.
Again, the meter can not measure your house’s total electricity intake (which is the sum of E and G in the diagram). It can only measure your grid imports (G). You’ll require to buy your own monitoring if you wish to see what’s going on ‘behind the meter’, and I’ll show you how to do that in Step 5: A monitoring system for your solar.
The concept of ‘behind the meter’ You expect your electrical energy meter to understand how much energy you use. Sounds obvious?
However, producing your own electrical energy requires a whole new state of mind. You might be amazed to find out that the meter installed by the electrical power merchant does not know– and can’t understand– the details of what is occurring with your home’s electricity.
When you have surplus solar, your meter can’t see just how much electrical energy your house is using or how much is being created by the solar system. It can just determine the exported solar.
For instance, if you’re exporting 2 kW of surplus solar your meter does not understand if you’re generating 3 kW and utilizing 1 kW, or if you’re producing 4.3 kW and utilizing 2.3 kW. All it knows is that the distinction is 2 kW.
2. Off-Grid Solar System
An off-grid solar energy system is not connected to the grid. But you already understood that.
What you might not appreciate is that an off-grid system that will give a typical Australian home almost the same benefit as being on-grid will cost at least $40,000. Why so much? Because it needs to be designed to work even in the depths of the winter season when there is extremely little sun. This implies it needs a much larger solar panel array to create as much power as possible in low light and to charge your batteries as well as powering your home. It likewise requires a large battery bank to keep as much energy as possible for the gloomy days and to manage any appliances that draw high power, even for brief durations.
An off-grid solar energy system is similar to an on-grid system, except that you require to add the following.
A battery inverter: Like solar panels, batteries produce DC voltage. The battery inverter transforms this to AC for your appliances to utilize. The battery inverter also houses the power electronics that constantly balance supply and need in the stand-alone system.
A battery bank: Any solar energy generated above your appliances’ needs, instead of going to the grid, charges your batteries. When the batteries are charged, the solar energy is throttled back so as not to damage the batteries. This suggests that the majority of the time, your solar panels are running method under their peak capability– wasting solar power if you like. When your photovoltaic panels are not producing sufficient power, the appliances draw power from the batteries.
A generator for backup: There will always be times when your batteries are drained pipes, and the sun refuses to come out. For these times, you require a backup generator.
Here are four reasons you may select to go off-grid.
There is literally no electrical power grid where you live. Maybe you live in the middle of the Simpson Desert like my Uncle Dave (seriously, he does!) or elsewhere similarly remote. Hey, there’s no lack of places like that in this big ol’ country of ours!
There is a grid, but the nearest connection point is a long way from your house, and your local electricity network wants to charge you an arm and a leg to link you. In this case, it may be less expensive to go off-grid. Be aware, however, that a decent-sized off-grid system for an extremely effective home is going to begin at about $30,000.
You are connected to the grid; however, you suffer frequent blackouts that trigger your grief. You want a system that can run when the grid is down, and you understand that a standard grid-connect solar system does not work when there’s a power cut unless it has a huge and expensive battery backup system or a backup generator (or both).
Your home is currently linked to the grid. Blackouts aren’t an issue (if they were, you’d currently have a generator), but you much like the sound of going off-grid. You believe it makes you more independent and secures you from the upcoming apocalypse. In fact, you’ve already got a huge shed to put the batteries in. It’s the same one where you stored all the canned food in readiness for the Y2K bug/end of the world last time around. You do not mind investing $30,000 on an off-grid system that would just cost $6,000 if it were grid-connected or maintaining it a lot more regularly than a grid-connect system or buying brand-new batteries every few years. Since you’re much closer to nature now, you’ve cut that grid connection.
I think what I’m trying to state is that unless 1, 2 or 3 above uses, it’s financially and ecologically insane to demand an off-grid solar service. It’s financially ridiculous since the expense is three to five times greater. It’s environmentally outrageous because of all those batteries you’ll require to buy (and change from time to time), which may consist of nasty chemicals. Batteries also minimize the efficiency of your solar system. Expect them to lose 10% to 30% of all the energy kept. There’s also all the solar energy that’s squandered when your batteries are full. With no grid to absorb excess solar energy, your solar panels will spend most of their time being throttled, so they do not overload your house and batteries.
Luckily, there’s a compromise: hybrid systems.
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3. Hybrid Solar System
Hybrid solar energy systems are the best of both worlds: you get the guaranteed (well, 99.9% of the time) electricity supply of the grid, with the capability to keep your excess solar power for use when the sun isn’t shining. This typically reduces your reliance on grid imports by 70% to 95%.
Hybrid systems are likewise at least half the rate of an off-grid system and do not need diesel backup. They’re still more costly than a purely on-grid system, though– typically double the price of grid-connect solar.
The only difference between a hybrid solar power system and a regular grid-connect system is the addition of batteries and a battery inverter.
A hybrid system is typically configured to charge the batteries with excess solar energy– as this is the most inexpensive type of energy you can get. Once the batteries are full, the excess solar gets sold to the grid, making you earnings.
When there is insufficient solar energy to power your home, the battery inverter will do its finest to offer power from the battery. If it can’t supply sufficient power (keep in mind, power is measured in kW) because it strikes its power score, or it can not supply adequate energy (kWh) because it is running flat, then the grid will offer the deficiency.
Generally, the batteries in hybrid planetary systems are sized to get you through the night; however, they can still pump out power during the day when needed. Hybrid systems are set up so that your house uses solar initially, then battery power, then– as a last resort– grid power. If you suffer a grid outage, some hybrid systems can supply restricted backup from your batteries to keep the lights on and some devices running.
I chose my words very thoroughly in the previous sentence.
I say ‘some’ hybrid systems because, counter-intuitively, lots of hybrid systems can’t supply backup power if the grid goes down. This is because running in ‘off-grid’ mode needs additional control and changing equipment, which costs a minimum of $1,000 more.
Even if you’re offered a battery that guarantees ‘backup’, it may not be the backup you’re anticipating. I’ll discuss this in detail in the battery section of Step 5.
In summary, a hybrid solar system is a grid-connect solar energy system with added batteries. It’s about a 3rd of the cost of an off-grid system, can sell excess solar instead of wasting it, and does not require a generator.
If you want batteries and you currently have a grid connection (or you’re developing and you can get connected to the grid for an affordable price), the hybrid is a much better option than off-grid.
So now the concern becomes: ‘Should I buy a standard grid-connect system or a hybrid?’.
Short answer: If your main motivation is optimum payback or helping the environment, then don’t buy batteries (yet).