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Net Metering
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What is Net Metering?

The diagram illustrates a typical installation. Net metering is the middle ground between generating all your own power similar to an off-grid home, and the previous microFIT installation where you sell all the power you generate at a subsidized rate to the IESO. Typically but not always a residential net metering system in Ontario is limited to a 10kW or less installation. Not shown in this diagram is a mandatory outside disconnect switch which isolates the electricity from the inverter from the grid for hydro crew safety purposes.

This is an arrangement between you and your local hydro company to swap power with the grid. When you have an excess of power beyond your own requirements, the excess is exported onto the grid. At night and when you use more power than you generate, you receive some or all of your power from the grid. Your solar system uses the grid as a virtual battery to store surplus power until it is needed. This is available in most provinces, but this requires your hydro company to offer net metering. Hydro One and Ottawa Hydro both supports net metering.

The existing house's smart meter is replaced by a bi-directional smart meter. The DC power flows from the solar panels into an inverter which outputs 240VAC synchronized to the hydro grid. It supplies power to your building, and any excess is exported to the grid. At night and when you consume more than you generate, the shortage in power is imported from the grid, and supplements any power generated by the PV panels. Usually there is no battery in this system. A significantly more expensive implementation with batteries and a different inverter is permitted and will provide power when the grid goes down.

 

You buy the power at the standard, non-time of use price, and when you export your excess power it is credited to your account at exactly the same rate that you purchase. Over the period of a year, you pay only for the power that you consume. If you generate more than you consume, you do not pay for the power, but you are NOT paid anything for the excess power. There is an an Ontario Ministry of Energy brochure that explains the financial model of net metering in more detail. If Hydro One is your local utility, they use a sliding 11 month window to reconcile your credits.

This requires a 60A 240VAC disconnect switch mounted outside near the meter base. Wires from the inverter connects to the disconnect switch which in turn connects to a dual breaker in your main panel. There is no need to change the meter base. .

Your existing house meter is changed to a bi-directional meter, instead of the normal unidirectional smart meter. This takes only a few seconds.

Many people expect to be paid for the excess power that they generate, but they are not. It is banked as a credit and reconciled on a one year window.

When you export to the grid in Ontario, you are credited a delivery charge at the same rate per kWh that you pay when you are using power from the grid. Therefore if you used no power over a year, or you generated more than you consumed, you pay no per kWh delivery charges. You do pay the same fixed monthly delivery charge. If you generated a little less than you consumed, you pay the per kWh on the net amount that you used from the grid, both for the kWh and for the delivery charge for the net amount.

There is no taxpayer subsidized rate paid to the producer, and power is bought and sold at the current market price.

Your savings are all in after income tax and after HST dollars! (This is due to you avoiding spending money, rather than earning income as in the expired microFIT program.)

Why Net Metering?

You wish for your solar installation to make economic sense and pay for itself in the long run and meanwhile it provides a green source of energy.

You may be concerned about the rising cost of electricity, a net-metering installation can protect against rising prices. The protection can be almost 100%, if you generate more than you consume. The only price that can rise is the fixed portion of the delivery charge. Your cost of electricity goes down, with an up front investment in solar power.

In a Globe and Mail article, the provincial Energy Minister announced "The province’s long-term energy plan, released Monday, projects a 42-per-cent jump in home power bills by 2018, climbing to 68 per cent by 2032. The cost for industrial enterprises will also rise, by 33 per cent in the next five years and 55 per cent in the next 20." This amounts to a 3% increase per year, until 2032.

Net metering is a safe investment with a reliable return. It can drive your hydro bill down to a small amount of fixed charges for having an electrical service. If you don't pay for any amount of power consumed, the energy savings will over time offset the cost of the installation, and from then on, you have almost free electricity. This is with the reliability and convenience of a grid power connection. If you have high hydro bills, this can provide a good return on investment, with no impact on your lifestyle as might happen with off-grid solar.

Net metering can have a better payback than solar thermal hot water heating, and there are a lot less moving parts - none. There is a lot less to go wrong. In a partially solar electrically powered house there are far more potential savings available if the electrical bill goes to zero, than if the hot water heating costs drop towards zero.

The more electricity your house uses, the greater the savings than are possible with net metering.
Do you wish to be power self sufficient, without the cost and maintenance of a large battery bank. The grid acts as your battery bank and does not need replacing every 10 years. Meanwhile you save money and help green the planet at no cost in the long term.

If you would be interested in discussing a net metering solar energy system please contact Ottawa Valley Photovoltaic to get started. Usually the first steps are a site survey and a review of your hydro bills to determine annual consumption.

graph hydro rates

This is supplied by the Ontario Energy Board and details the 2 tiered price of electricity BEFORE delivery and regulatory charges and before HST. The key observation is that overall the cost of electricity is rising at a steady rate and over the time frame of 15 years has gone up 250%. Since 2002 it has gone up 300%. The blue line is most important as most homes are using only the lower tiered pricing if they use less than 12,000 kWh per year which is the 2020 threshold between the two tiers.

What is the process for a net metering system installation?

We have a guide that outlines buying a complete net metering solar installation.

 

Will I have power if the grid goes down?

A common misconception and expectation is that you will still have power if the grid goes down since you have solar panels. The most common form of net-metering has no batteries. If you have a battery free version of net-metering, you will loose power if the grid goes down. For safety reasons all the approved inverters must shut down immediately when the grid goes down, so you don't electrocute the hydro staff repairing the problem.

At night, the panels do not generate any power, so panels without batteries can't keep your lights on. The power has to come from another source, which could be a battery or a standby generator.

If always keeping the lights on is one of your major objectives, there are two approaches.

  1. You need a battery, therefore net-metering is implemented as an off-grid system with the grid providing the backup instead of a generator. You need an off-grid inverter which has grid tie capabilities. You have all of the off grid components except for the automatic standby generator. This is the more expensive and more complicated approach.
  2. The less expensive way to provide lights when the grid is down is to use a normal grid-tie inverters, with no batteries and have a standby generator and a transfer switch.

In 2022 there are grid tie inverters that can also operate to supply power if the grid goes down. They have an automatic transfer switch and then once isolated from the grid they can start up again and create a local grid. This require a battery to be part of the system and the battery supplies power at night. This does add significantly to the cost of a net metering system. When the grid is restored or the sun starts to shine the battery begins to recharge. If you wish to have a battery backup as part of a net metering system then contact us and ask for a paper we have written on this topic. Meanwhile here is a bit of economic perspective.

Batteries are the dominant cost of the battery backup portion of a net metering system with backup capability. Roughly from a series of hydro bills work out how many kWh you use per day in the winter. Multiple that by 20% as the minimum amount of electricity would would use per day during a grid outage with extreme conservation. Then multiply by 2 or 3 days. This will give you the amount of power you need to store in a battery bank. A new year round off-grid home typically uses 4-6 kWh per day. If we take a typical case of 20 kWh per day, the Ontario average and do the math for 3 days, that is 12 kWh. If the sun does not shine for several days as during a winter storm and the battery is depleted you will be in the dark unless you also have a backup generator.

Also in the wintertime after a snow storm and the snow has stopped falling what happens? If the panels are ground mounted they can be brushed off and then when the sun shines they will resume generating power. What if the panels are mounted on a 2nd storey roof. It is unsafe and impractical to mechanically brush of the panels. Therefore they remain snow covered until the temperature rises above the freezing point for sufficient time to melt the snow off the panels. If the grid is still down it would be unpleasant to wait a week or two in January for a warm day to restore solar panel operation. For example, only about 40% of Januaries in Ottawa experience such a thaw of two days.

A lithium Iron Phosphate battery costs between $800 and $1800 per kWh and is good for about 10000 cycles.

A good AGM lead acid battery (no maintenance) designed for solar applications costs between $400 to $500 per kWh and is good for about 1000 cycles.

A flooded lead acid battery (requires maintenance) designed for solar applications costs about $160 to $400 per kWh. (And you can't discharge it 100%) It is good for 1200 cycles if you only discharge it 50%.

Since you may only have 2 or 3 outages a year, then you may only do 2 to 5 cycles a year. Therefore the Lithium batteries which are capable of a much greater number of cycle will die of old age before you use all of its cycles, (2000 years) and even the lead acid batteries used for backup purposes you will never use 1000 cycles.

Therefore, I do not recommend buying Lithium Iron Phosphate batteries for this application. AGM batteries are the best choice for a no maintenance battery. However this still costs $5424 just for the example battery bank. (For off-grid applications the math is completely different.)

 

Can I install a net metering system myself?

Yes you can. There is a sample list of parts costs for a bungalow Parts. Also see our FAQ for more details. and a list of steps involved for a DIY installation Steps for DIY.

At the current price for electricity without subsidy our financial analysis tool projects a DIY system could result in a break even period of about 6 years. It would be slightly longer in an urban area as urban residents have a lower delivery charge than rural customers in Hydro One territory.

 

What do you use and recomend for backup when there is a power outage?

I have a 10 kW microFIT solar installation, which I do not use to power my house during a grid outage. I use a 9 kW gasoline powered generator which cost a little over $1000. The generator must output 240VAC to connect to a whole house! This allows me to run everything except electric heat and we have wood heat for heating backup. In addition I have a 1 kW Ecoflow Delta 2 portable power appliance which I use to power my phone, router and internet related equipment. The Ecoflow stores power in an internal Lithium Iron Phosphate battery. This can run this equipment for about 33 hours on a full charge. It will recharge in 80 minutes which is a very important feature. I plan to run my generator at meal times but not all the time we are awake. There are many times during the day when the only power consuming devices are the internet and telephone equipment. Without the Ecoflow Delta 2 I found we were often running the generator during the day only so we could make phone calls or use the internet with our phones or laptops. This was quite fuel inefficient and we had the generator noise in the background.

With the addition of the Ecoflow Delta 2 in our system, the generator can be switched off between meals and when it is running it rapidly recharges the Ecoflow appliance. With an all in one desktop computer running the Ecoflow can keep providing power for up to 16 hours, and when I also run on a desktop computer and it's monitor the Ecoflow can power both the desktop, the all in one computer and the essential internet and telephone for 6 hours.

The Ecoflow is not connected to the household wiring in any way. You just plug the power cords of devices that you wish to power into outlets in the back of the appliance. If you want to power a floor lamp in another room you just use an extension cord.

Instead of running the computers you could plug in a couple of LED lights for the evening instead of running the generator, and could leave one light on overnight.

The Ecoflow product is ideally suited for this type of service due to its very fast recharge time, and it can and does act similar to a UPS. It does not switch as fast as a UPS, and does not claim to protect against power surges but all the equipment in my house that I wish to run from this power source tolerates the slower (30 ms) switching time without noticing the gap in power when switching between hydro and the internal battery.

This also cost a little over $1200 so the combined cost of approximately $2.2k is much less that a battery system integrated into the solar system. And if we have a multi-day power outage we can use vastly more power than we could use if we had a solar charged battery and the weather was overcast, etc.

Instead of trying to get by with a use of 1 to 3 kWh per day for 3 days from a 10kW battery bank and then having nothing after that if the sun does not choose to shine, my 9 kw generator could in theory supply 9 *24 = 216 kWh in a day, much more than the average 20 kWh used per day by an Ontario home without electric heating.

With the Ecoflow we have phone and internet and laptop and phone charging for 24 hours a day during the power outage. With this configuration there are many hours when there is no need to run the generator.

Any system that provides an alternative source of power to all or a critical load sub-panel requires either a transfer switch or an GenerLink to connect to the household wiring. Therefore I have excluded it from the cost of the backup power source.

I have also assumed a manually initiated electric start generator that is stored in a garage or in a shed and wheeled out to plug into the cable from the transfer switch when a power cut occurs. This is my approach. You can spend a LOT more money and buy a propane fueled Generac or Kohler automatic start backup device that is located outside permanently, wired permanently to an automatic transfer switch and starts and stops itself automatically commanded by the automatic transfer switch when there is a power outage. That is the premium approach. That can add up to $20k to the price tag.

Disclaimer: I do not sell the Ecoflow portable power appliance, and I have not named the brand of generator that I use. I have no financial interest in suggesting that my model for dealing with grid outages may be better than using batteries, inverters, charge controllers and other items required to tie into your solar panels for backup power.

What would a typical turnkey net metering system cost?

An average cost for a 10kW net metering roof mounted system in Ontario if you do an internet search in 2020 the results would be: If you hire a company to do everything to put a net metering system on your roof you might expect to pay about $24,600 for a 10 kW system. This is an average installed cost in Ontario in 2020 of $2.46/Watt. This is a basic system with no more than 10kW of panels. This figure appears in many places on the internet but none of these sites provides any details of the system they claim is typical.

This would be a basic system without any premium features. It would use a central string inverter, have all the panels installed in a single rectangular array on an asphalt shingle roof with a 30 degree slope or less. It would use simple L foot mounting instead of deluxe waterproof flashing for each fastener penetration. It would have no obstacles on the roof to work around such as attic vents or plumbing stacks or chimneys.

In 2022 a more realistic cost would be about $3.01 / Watt, or $30,100 for a typical system that might use micro-inverters or premium panels. Soaring transportation costs make the panels and racking components more costly as they are heavy and are delivered by commercial truck freight companies. Ocean transport of panels is now slower and more expensive.

Any ground mounted system would cost more due to more materials required to build the support frame.

What can I do to lower the system cost?

You can partly or completely install the system yourself to reduce or eliminate the

costs.

You can participate in the Canada Greener Homes Grant program and apply for a $5000 grant for your solar panels or inverters. This only available for you principle residence that you own. You must have the pre-retrofit audit done before incurring any solar project expenses to qualify for the grant.

 

What sized net metering systems are permitted?

For a simplified, no charge application process and minimal regulation in ontario a residential net metering system must be 10kW peak generation capacity or less. Nearly all current residential net metering systems meet this definition.

For net metering above 10kW a a different commercial application is required and it is not free! Each different hydro utility has its own application forms and fees that they charge. There is a significant amount of paperwork and the application process can take a considerable time and require technical expertise. The maximum size permitted varies with each utility.

Hydro One

For a 10kW or less you apply with a Form C and then if approved you pay a connection charge of $800 + HST if you proceed with your project. This is to pay for the bi-directional smart meter and for the change in connection.

For an over 10kW up to 150 kW application you begin with (Form B and a $3329.86 + HST application fee to do a Connection Impact Assessment). This will determine if there is capacity to connect your project to the grid and what upgrades to the hydro's infrastructure that will be required to make the grid ready to accept your generated power. If there is no capacity to accept your generated power this fee will be refunded. Under all other conditions this fee is not refundable, and if you later decide not to complete the project there will not be any refund. There will be other fees if Hydro One has to upgrade any of their equipment such as a larger transformer. These upgrades and associated fees are detailed in the response you receive to your form B application. If there are no upgrades required the application fee is the only fee you pay, the cost of changing the meter is included.

Also note: Hydro One requires "All technical submissions (Form B, single line diagrams, etc.) for projects greater than 10 kW must be signed and sealed by a licensed Ontario Professional Engineer (P.Eng)​​​​​​​​​​​​​​​​". This will also cost you a fee if you have to hire a P.Eng to fill in the application for you. We are not licensed as a P.Eng.

Hydro Ottawa

For an under 10kW the application process to determine if you can be connected is free. If you proceed with the project there is a $1191.82 including HST fee to connect.

Hydro Ottawa's application fee for applications over 10 kW up to 500 kW is $1000 + HST.

 

Ontario limits under 10kW to roof mount only, then revoked

On July 1 2018 the Ontario regulation R18274-e came into effect. This has a limitation that applies to ground mounted systems. Systems under 10kW, (in this regulation described as residential residential-rate classification) can no longer be ground mounted. On June 9, 2021 this regulation of ground mounted systems under 10kW was revoked.

Now in Ontario the local municipal government has the authority to regulate the location of ground mounted solar systems, instead of the province.

Ontario Regulation for Greater Than 10kW Ground Mounted Systems

Commercial systems with a generation capacity of over 10kW can be ground mounted, and this must be on land that is not prime agricultural land. There are more details and I suggest that you read the actual regulation if you are interested in a ground mounted system over 10kW and less than 150 kW if Hydro One and less than 500kW if Hydro Ottawa.

Qualifying for a commercial ground mounted connection includes meeting a 183 page long set of technical requirements set out by Hydro One and other utilities will be similar. There are costs involved for a grid impact study to determining if you can be connected to the grid, unlike the under 10kW case which is free. There is also requirements under the Green Energy Act, 2009 for an environmental impact study. However some small facilities may qualify for the less expensive EASR registry approach to environmental issues. I suggest that you read the "Small ground-mounted solar facilities user guide for Environmental Activity and Sector Registry" document available on the https://www.ontario.ca/page/small-ground-mounted-solar-facilities-user-guide-environmental-activity-sector-registry-easr web site.

Ground mount or roof mount?

As discussed on the off_grid 4k BOM page, due to the recent Ontario electrical code requirements for AFCI and Rapid Shutdown, many off grid solar installations are less expensive when installed on a ground mounted racking compared to the same number of panels on a roof.

There are some other considerations as well as the cost that favour a ground mount installation. These are:

A new construction project can orient the house or cottage for the best view, etc without having the roof face south for the best productivity of the solar panels. The ground mount should face due south. With the expense of a longer run of wire it can also be located somewhat out of sight.

Also there are a lot less constraints on the shape and style of a roof if it does not need to hold solar panels.

With ground mounted panels they are located where there will be minimal shading. That permits locating the house or cottage where there may be a lot of trees or other sources of shading.

The tilt of the panels can and probably will be steeper than a roof giving better winter time production of power. A greater tilt also makes snow removal easier.

For a 4 season house or cottage clearing snow from the solar panels is critical for maximum energy capture. There are less sunny days in the winter and the days are shorter. Mounted on a bungalow roof the panels are hard work to keep clear of snow accumulation. If the house is a two storey building then clearing snow from the panels on a roof is extremely difficult and dangerous. Therefore snow clearing is much safer when the solar panels are ground mounted.

With a ground mount there are no roof penetrations, no sources of leaks and when it comes time to re-shingle there is no requirement to remove and then re-install the solar panels.

Now for my most valuable hint: plan a ground mount so the lowest edge of the solar panel is high enough to be above the peak winter snow fall depth, AND provide some extra clearance so that when a snow accumulation avalanches off the panels it will not pile up high enough to prevent all the snow dropping off the panels onto the ground. If there is not enough height you can encounter the situation where you have to shovel the pile of compacted snow away from the bottom of the panels so all of the bottom panels are exposed to the sun. Furthermore make provision so that a snow blower can be used to move the pile of snow at the base of the panels away from the panels ready for the next snow storm. Take this into account if you choose to use a fence to keep kids and animals away from the back side of the solar panel wiring. 3 to 4' from the ground to the lowest edge of the panels is about right.

For a DIY installation the work is much safer when assembling a ground mount racking system and then installing the panels. Working on a sloped roof is always more hazardous.

 

What extra electrical equipment does net metering need?

  • You require the installation of an isolation switch (visible, accessible and lockable) located
    between the solar system and the customer's load center circuit breaker, at a location beside the meter if practical, or some other location acceptable to your local hydro.
  • You connect the output of your inverter to a double breaker in your existing electrical panel
  • The local hydro changes the meter to a bi-directional unit.
  • Hydro One charges $800 + HST for the replacement meter and setup of a net metering service.

What services do we offer for net metering projects?

  • We offer site surveys to determine the suitability for solar power, the impact of shading. As part of the site survey we provide a tutorial on important aspects of a solar system and how you might choose to install it yourself. This also permits us to subsequently calculate an estimated costed bill of materials for the recommended installation.
  • We can provide a kit delivered to your site of all of the solar components that are needed for a project.
  • We can assist a DIY owner to install a net-metering system.
  • We have a tool to calculate the savings that are possible, and predict the break even point. There is an example for an average home.
  •  

     

Can I participate?

You do need an approval from you local hydro company, and that approval is subject the a transmission capacity limit. In Ontario the maximum size for simplified, non-commercial systems is 10kW of inverter capacity. Note: Hydro One and Hydro Ottawa both permit using a reasonable amount of excess DC (panel) nameplate rating over 10 kW so that the system can deliver the 10kW AC maximum to the grid during a wider portion of the daylight hours. In the rest of Canada, you need to contact your local hydro to find out their limits.

This over driving of the inverters is useful and beneficial when using micro inverters which do not have the same AC output rating as the attached higher wattage solar panels . In some cases there are no matching maximum output panels available to match the maximum output of available CSA approved micro inverters.

What if my local hydro company does not support net metering, or they do but there is not sufficient capacity?

Then you can achieve the similar benefits of an almost zero hydro bill by installing an off-grid style solar system, and attach the grid connection in the place of a backup generator. You only accept power from the grid, and do not generate surplus power onto the grid, thus you do not need any hydro's permission to operate. Please contact us to discuss this further. There are some subtle choices to be made. Unlike typical net metering, since you have a battery you do not loose power if the grid goes down in a storm. However, this is a considerably more expensive type of installation and the benefits are less tan would be achieved by net metering.

Economics -- What sized installation is best?

If you look up your annual yearly electricity use for the last 3 years, (You can get this from hydro) then the optimum size is about 125% of that capacity per year. We need to know some details about your site, and its shading to be able to de-rate the panels to calculate their production at your site. We also allow that the panels will drop in productivity to 80% of the original output after 25 years, so this would remain capable of a zero kWh bill for 25 years. It also would be wise to plan how extra panels could be added to the system in an efficient manner in case your electrical needs grow with a family or changes in life style.

If you have an Canada wide average consumption of 19 kWh per day.(Based on 720 households) You would need a system that is smaller in capacity than a 10kW system, and therefore the cost would be less. A typical 10kW system would supply 2 times the power used by the average home with 19kWh per day.

Using our recommended mounting orientation, shading at your site, and the productivity rating of 1 kW of panels in your location, determine the kW rating of the panels to generate the required amount in one year. If there is any shading, you will need the results of our shading analysis tool to do this calculation. If there is no shade, then this can be done with the use of the PVwatts tool available online.

if your calculated installation is 10kW or less, you have a simplified application to your utility. If however you wish to have over 10 kW of inverter nameplate capacity, you have to fill in a commercial application and go through the more extensive application process. The application to determine if there is enough grid capacity is not free. This has vastly more paperwork, and requires connection impact study, etc. If there are any upgrades required to prepare the hydro's infrastructure such as a different transformer you are charged the cost off all the upgrades. Most home owners do not wish to take this route and select the 10kW and under application process. The rules are different in Quebec, and more favourable.

Sample break even analysis tool

We created a tool to predict the break even point, and the savings for the next 30 years. We can use this to predict the financial results of your specific project.

The example output from this tool can be viewed in a PDF file. The assumptions in this particular run are a typical Ontario house with an EV (Electric Vehicle):

  • 2022 prices for installation on a turnkey basis
  • 10 kW net metering system with 12kW of panels
  • When the electricity consumption is exactly matched to your generation capacity you get the best return. In a practical example provided here the electricity generated exceeds the amount consumed for the first 10 years. After 20 years this sample home starts to pay for a small amount of electricity used each year, while still saving about $3000 a year in electricity that is not purchased. This is due to LID which means the panel output slowly drops over time.
  • Location Ottawa, served by Hydro Ottawa
  • The panels are roof mounted, face due south, and are at a 45 degree tilt, and there is no shading
  • The current (November 2022) hydro price per delivered kWh . This includes delivery charges, and HST and omits any temporary rate reduction.
  • The prices for hydro will grow by 3% each year, as predicted by the Ontario Ministry of Energy
  • The cost of the system includes installation, but is approximate.
  • The OEB stated in a 2016 report that the average Ontario household used 750 kWh per month. This is the household consumption used for this example.
  • The house does not use electric heat.
  • Now with the advent of electric vehicles that are expected to be charged at home overnight a household with an EV should plan for extra power consumption due to an EV. This example assumes you drive an EV 20,000 km and it goes about 5 kM on 1 kWh, this adds 4000 kWh to your hydro consumption if you charged exclusively at home.
  • There is be an allowance for LID (Light Induced Degradation) so that you still meet your objectives of generating all you consume after at least 10 years.
  • There is also a 2nd example of the same house with a smaller system due to no EV in its future.

The current 2 tiered price of electricity per kWh varies for different hydo utilities and the density class you are in. These prices include HST which is important as it is part of the expense that you avoid when generating your own power. These numbers ignore the Covid-19 temporary price reductions, so that they reflect the long term cost.

Net metering customers must use 2 tiered pricing and can NOT use Time Of Use pricing in Ontario.

* Note that normally you plan a net metering system to generate a little more, such as about 20% more that you consume on average. This gives some margin and also allows for a drop in the output of the solar panels over time as they age.

Note with time the output of solar panels decreases. However with time the hydro rates are rising at a much faster rate so the money saved each year is still increasing even with a drop in panel output.

If you consult the graph earlier on this page you will see that the electricity cost has gone up considerably higher rate than 3% a year, so that the return on investment will be better than this tool predicts. In the last 10 years the price of generation has doubled.

Maximizing Net Metering System Production

First of all, mount the panels so that they point due south, if possible. Have the slope of the panels between 30 and 45 degrees In the ottawa region. (Latitude to latitude - 15 degrees). Install 10 kW of total inverter nameplate capacity, the maximum allowed. If you have 10 kW of inverter capacity, you are permitted by Hydro One to connect a reasonable amount more panels so that your system is theoretically capable of supplying 10kW of AC power to the grid over a longer portion of the day, not just at noon. This can be useful if using micro inverters, which come in different wattage ratings than the most commonly available panels. It is even easier to do with string inverters.

For example with the Enphase IQ7PLUS-72-US Micro inverter which has a 295 VA maximum output there are not currently a supply of 295W output panels. However there are 330 and 400W panels which can be used with these inverters. This provided extra generated power as it does not begin to stop clipping the output until later on in the day during the shoulder hours, this capturing more energy during a day than would be obtained with a 295 W panel.

The math for the above is a maximum of 33 Enphase micro inverters, and 33 panels that range between 295 and 400W per panel, which is the highest commonly available on the day that this text was updated. That yields 13,200W of nameplate panel capacity. If you used 295W panels instead then you would have 9,735W of panel nameplate capacity. At solar noon both configurations would supply the same amount of power to the grid. Later on in the day when the sun is not as bright and is lower in the sky the system with 400W panels will still be supplying 295W to the inverter and thus to the grid. Thus the daily production is higher due to the clipping effect of the inverter limited configuration.

 

Are 3rd party net metering agreements possible in Ontario?

On April 21, 2022 the Ontario government changed some of the rules concerning net metering to permit 3rd party agreements. The new arrangements are:

  • Solar lease: A customer pays a third-party developer for the use of an on-site solar PV system over a specified period of time, rather than paying for the power generated –pay per month (e.g., 15-year term); 
  • PPA: A third-party developer sells the power generated by an on-site solar PV system to the customer for a fixed period of time (e.g., 15-year term) and at a fixed per-kWh rate (less than what is charged by the LDC). PPAs inherently afford greater consumer protection as consumers only pay for power produced. 
This may be limited to rooftop solar only, the announcement was not clear.