Reduce Your Energy Bills - Grid Tie Solar System
27 Jan 2023
What is a grid tied solar system?
Grid-tied solar systems are the simplest type of solar system. As there is no energy storage equipment in this system, any power generated by the solar panels that is not used immediately gets fed into the main grid. When energy generation from the panels is insufficient to match energy usage, drawing power from the main grid makes up any shortfall.
Advantages of a grid tied solar system
Grid tied solar systems have several key advantages that contribute to them being the most popular type of solar setup. These advantages include:
As the simplest type of solar setup, grid-tied solar systems require less equipment, mainly due to the fact that they are the only type of solar system that doesn’t require a battery. This makes them more straightforward to install than other options, such as off-grid or hybrid systems. This simplicity generally translates to savings for the customer, making grid-tied solar the most accessible form of solar power for most people.
Flexible, reliable power
Having your energy supply linked to both solar panels and the main grid offers all the major benefits of solar (such as cheaper power and a lower carbon footprint), but still gives you the reliability of the grid.
Arguably the greatest benefit of a grid-tied system over an off-grid system is the ability to feed excess electricity into the grid. This process earns you credit from your energy provider, which can reduce the cost of your energy bill significantly.
What is a grid-tied solar system?
An on-grid solar system is one that is connected to the main electricity grid. They can operate without being connected to a solar battery therefore making them the most simple, cost effective, and popular type of solar system.
The main types of solar systems to choose from are grid-tied, off-grid, and hybrid.
A grid-tied system is, as we’ve covered above, linked to both the solar panels and the main grid. This means that you can draw power from either the panels or the grid, and also automatically feed excess solar power into the grid. As such, different equipment is used to that used in off-grid systems.
Off-grid systems differ in that they are not linked to the main electricity grid. Instead, they operate as a closed system, making them ideal for areas that do not have grid access. To ensure reliable access to power, off-grid systems will generally also include a battery system and a backup generator.
Hybrid solar systems combine some of the elements of the other two systems, making them an attractive option for those looking for flexibility. Hybrid systems include solar panels, batteries, and a grid connection, as well as a generator in some cases. This means users can dynamically switch between energy sources depending on price, energy production, and energy usage.
What does a hybrid grid tied system look like?
A hybrid grid tie adds battery storage to your system. So during the day the batteries can also be charged from your solar panels and you can draw upon them during the evening or when you need. This means you do not have to take electricity from the grid. You can also recharge the batteries if needed during the night when electricity is cheaper from the grid.
Equipment required for a grid tied system?
As grid-tied systems are connected to both a solar panel array and the main grid, they require some specialized equipment. For example, grid-tied systems need a grid-tied inverter (GTI) (such as a suitable central inverter, string inverter or microinverter). These inverters convert the direct current (DC) from your solar panels to alternating current (AC) to feed into the grid and to power appliances.
Microinverters can also be used in a grid-tied system, and can make your solar setup more efficient when compared with standard grid-tied inverters.
Another key piece of equipment is a two-way power meter. A power meter measures the electricity going from your system into the grid, and from the grid into your system.
It is also a good idea to add a MidNite solar surge protector device to your system. This protects against lightning strikes and any surges on your electrical devices.
How to size and install a Grid Tie System
For a grid-tie solar system we usually want to offset as much of our annual electricity use as possible, but no more than that! Almost every province in Canada has annual net-metering, which allows for ‘banking’ of excess energy production for use within 12 months. This means we can overproduce in summer and use up the excess in winter. Any credits left over after one year, are usually not paid for, but given away to the utility. So how much electricity do you use per year?
The easiest way to determine how much energy you use annually is by taking a look at your electricity bills. You simply add up your bills for each month of the past year to get an overall annual Kilowatt-hour (kWh) value. Unfortunately you can’t just take one month and multiply by 12, electrical use generally changes quite a bit throughout the year so this number would not be accurate. The average Canadian household uses around 1,000 kWh per month, or about 12,000 kWh per year. Few people are ‘average’ so your numbers may be very different.
The next step is to convert your annual electricity use into a number of solar panels, or kW of solar, that it will take to generate the amount of energy you want to offset per average year. As the saying goes, the three most important things for this are “location, location, and location”: Solar panels in southern Ontario for example will perform very differently from solar panels in northern Nunavut. The table on the next page will give you a good idea what to expect for your location:
Calculating the number of solar panels needed
This table will help us calculate the number of panels needed. Find your location in the left column. The second column shows how many kWh to expect for every kW of solar panels, when those panels are mounted facing south, at a tilt-angle equal to the latitude of the location, and if there is no shading of the panels at all. The two columns to the right of this show annual energy yield in kWh for panels mounted at a tilt-angle 15 degrees steeper, and 15 degrees less steep than the latitude. One interesting aspect is that for most locations a tilt-angle that is less steep than the latitude actually does a little bit better annually (for example, for Ottawa the best tilt-angle for annual energy production is actually around 40 degrees, while the latitude is 45 degrees).
Calculate Number of Solar Panels you will need: In this example we are using the location of Kelowna in British Columbia (see table)
Solar Panels (kW) = Total annual energy use (kWh) / Solar energy per kW of panels
12,000 / 1132 = 10.6 kW of solar panels
To find out how many solar panels that is we have to divide by the size of each PV module. So let's take a single 360 Watt solar panel, and 360 Watt equals 0.360 kW (“kilo” just means thousand). Punching these numbers into our trusty calculator we get:
10.6 / 0.360 = 29.4 solar panels (30 x 360 kW solar panels are needed to meet your annual electricity usage.
N.B. Now you have to work out whether you have enough physical room on your roof or backyard to accommodate that number of panels. Or recalculate with a higher performance solar panel ie. 425W (22.3 or 23 solar panels)
The next page looks at calculating your roof area.
How to Calculate Roof area for number of solar panels
Now you know ideally the number of solar panels you would like to install you have to calculate whether your roof area can physically accommodate them. Using a tape measure you can get a good idea without having to get on the roof. Don't forget to add any overhangs and also be aware of any obstructions, vents on your roof where the panels can not lay over. You might have dimensions when you bought the property already or just use a calculator width x length. Leave 18-36 inches from the edge for install. Take the area for each panel (see manufacturers dimensions) and see how many will fit on the area you have calculated. Its best to do this on a piece of paper so you know exactly where to install the panels.
Calculate Gable roof: To calculate your roof area, simply multiply your roof length by your roof slope height, and multiply this by two. This should give you the total area of your roof, not accounting for a chimney or other sections of your roof not covered by tiles.
(Roof Length x Roof Slope Height) x 2 = Roof Area
Let’s say we have a typical home with a gable roof. The roof slope height is 7m, with a 9m roof length and a pitch of 45 degrees. Therefore, using our above calculation:
(7m x 9m) x 2 = 126m2
So you now know how many panels, how many you can actually fit on your roof. Don’t forget solar panels vary in performance and dimensions so you might have to play around with the best configuration.
So your ready to install
Contact CDN Solar. We will walk through your requirements and calculations and make sure you have the right system. Then just simply order online and you can either pick up in Kelowna or we can ship across Canada to your location.
First you need to check the size of your electrical panel. Is it a, 30 amp, 60 amp, 100 amp or a 200 amp panel. The main on/off breaker usually has a sticker or is stamped with it on. It needs to be 200 amp for Grid Tie
Work with your local electrician
You will need a Permit from your local city. We advise working with a local electrician. As many already have permit approval so this saves you from submitting electrical diagrams etc.
We highly recommend using your local electrician to connect your Grid Tie to your electrical panel etc.
Install Panels on Roof. You may be happy to install the panels yourself (we provide full instructions and fixtures) or you may prefer to hire a roofer / handy person
Overview of Grid Tie
Installation Videos From Hoymiles
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