## The expert guide to comparing solar quotes in Alberta

#### 1. Research your home’s solar potential

Solar potential (or photovoltaic potential)  is the expected annual kilowatt-hours (kWh) of electricity production resulting from 1 kW of solar installed on your roof. So, if a 5 kW solar array produces 5,500 kWh in one year, the solar potential is 5,500/5 = 1,100 kWh/kW.

Use this Natural Resources Canada (NRCAN) map to help you determine what the maximum photovoltaic potential is in your area. Note that the map shows the kWh/kW for a south-facing unshaded solar array. If your roof is partially shaded or not oriented directly south, then the solar potential will be lower.

Solar installers will use special modelling software to understand and predict losses due to shading and roof orientation. Each solar quote will include annual estimated electricity production in kWh as well as a solar array size in kW. Divide these two numbers to determine what photovoltaic potential the installer is assuming.

According to the NRCAN map, a south-facing unshaded solar array (angled at latitude) in Edmonton has a photovoltaic potential of 1,200-1,300 kWh/kW. Use this as a maximum. Solar panels on a flat roof in Edmonton will achieve ~950 kWh/kW.

#### 2. Identify deceiving financials

Calculating the financial metrics for solar can be complicated and misleading depending on what assumptions are used. Exaggerating some estimates can mislead a property owner into thinking that a solar quote will provide a better financial return than reality. Here are some examples:

• Overestimated solar potential
• Overestimated future rise in grid electricity costs
• Underestimated portion of solar electricity exported to the grid
• Overestimated inflation rate

For instance, if installer A claims that the solar potential of your roof is 1,250 kWh/kW while installer B assumes 1,000. The financials of Installer A’s solar quote will be significantly better since they are assuming more production from their solar system.

Glean ensures that each quote’s photovoltaic potential is realistic based on roof orientation, shading and location. Glean also calculates all financials with conservative estimates using the Alberta Solar Calculator. This gives you the confidence that financial metrics for solar quotes gathered by Glean can be compared apples-to-apples. We leave no room for overly optimistic financials since we believe under-promising and over-delivering is best for the solar industry long term. Solar makes sense – the financial analysis should too!

#### 3. Understand how much solar typically costs

Before government grants and taxes, Glean is currently seeing the following average costs for rooftop residential solar in Alberta:

Please note that the costs shown above are based on the past 2 years of historical pricing data. In some cases, a solar installation on your home may be more expensive for the following reasons:

• If your electricity use is very low, your system size will be small which may increase the cost/watt (unit cost) since smaller solar arrays cannot benefit from economies of scale.
• A steep roof may require scaffolding or additional safety measures which will increase costs.
• An old or damaged roof may need replacement before solar panels can be installed.
• A rural or remote location that is far from major cities/towns will require increased travel costs.
• An older home may have electrical components that need replacement.

#### 4. Compare inverter types

Residential solar inverters come in three main categories:

• Microinverters
• String Inverters
• D/C Optimizers

Inverters change D/C electricity that is produced by solar panels into A/C electricity that can be used by your home. See our guide to the anatomy of solar for more detail about the role of inverters. Here are some basics about each inverter type.

Microinverters are module-level inverters meaning they are mounted on the roof along with the solar panels. Each microinverter is connected to either 1, 2 or 4 solar panels. So, the D/C to A/C electricity conversion occurs on your roof.

Microinverters prevent the shading of one solar panel to affect the total output of the rest of the solar array. They also allow the production from each solar panel to be tracked and monitored which can help identify problems.

Best use: Use microinverters when solar panels sit on more than one roof face and/or when some shading from trees or buildings will occur.

Typically, residential solar installations require one or two string inverters installed on a wall inside or outside your home. The term string means that solar panels are connected electrically in series. The electricity from 6-12 solar panels flows into a string inverter which converts it from D/C electricity to A/C electricity that is usable in your home.

The major downside to string inverters is that when one panel in the inverter’s string is shaded, the power from all solar panels on that string gets reduced. This is why partially shaded roofs are not the best candidate for string inverters.

Best use: Use string inverters when all solar panels sit at the same roof angle and shading is not a concern.

D/C optimizers are used alongside string inverters to solve the partial shading problem. The partial shading problem can be solved by using D/C optimizers.

The optimizers are mounted to the back of each solar panel similar to microinverters. They track and regulate peak output and voltage before electricity flows to the string inverter. This optimizes the performance of each solar panel despite shading and orientation differences.

Your roof’s orientation, design and shading will all contribute to answering this question. In some cases, you may get quotes from different installers with different opinions on which inverter setup to use. Here are some questions you can ask installers to get more information from installers:

• Why did you choose this type of inverter?
• How would using a different inverter type affect the cost of the system?
• Do you expect that I will have to replace my inverter(s)? If so, when?

In most cases, the most cost-effective inverter will be your best choice.

#### 5. Compare solar panel types

Solar panels are rated based on the power (kilo-Watts or Watts) they produce at STC (Standard Temperature and Conditions). The size of solar panels is always increasing and so is the number of companies producing solar panels. A Tier 1 solar panel manufacturer meets the highest production standards. Glean always identifies if the solar panel manufacturer holds this rating and provides information about the product and its warranty.

#### 6. Look for these warranty lengths

The length of warranties varies between installers and manufacturers. In general, we recommend looking for the following at minimum:

• 25-year production warranty for solar panels
• 10-year manufacturers warranty for solar panels
• 10-year warranty for inverters
• 3-year installer workmanship and labour warranty

Each installer quote must have a general layout included to show you how the solar array will look on your roof. You don’t have to be an experienced solar designer to ask questions about the design below:

• Question 1: Why is the solar array is covering roof penetrations? In some instances, solar panels can cover roof vents, pipes or chimneys but not always.
• Question 2: Why is alignment uneven for the bottom row of solar panels? Uneven layout designs can be a red flag!
• Question 3: Why is that solar panel spaning more than one roof face? In general, each panel should sit flush with only one roof face.
• Question 4: Why is the edge of the solar array is hanging over the edge of the roof? No part of a solar array should hang over the edge of the roof.

Instead, a design like the one below has none of the issues mentioned above in the first place:

#### 8. Ensure your installer has the right qualifications

Glean requires that each solar installer:

• has comprehensive general liability (CGL) insurance
• has Workers Compensation Board (WCB) insurance
• is a member of Solar Alberta
• has a reputation for excellent customer service and quality solar installations
• uses high-quality solar equipment

These are required from all Glean solar installers.

#### 9. Know that quotes can change

Solar quotes aren’t final until you sign a contract. If you like everything about a specific quote except one or two things, it is reasonable to inquire about modifying the quote to fit your needs.

#### Conclusion

Your home and roof are unique and your solar quotes should represent that accurately. The best way to ensure you choose the best solar installer for the best price is to get multiple quotes. To save time, let Glean source 3 solar quotes for you for free.

Glean is a broker of solar quotes that was built by Canadians to make solar easier for Canadians. We provide you with 3 solar quotes, an easy-to-compare quote summary (that includes a detailed financial analysis) and a quote review call to answer your questions. Our service is free for homeowners! With Glean, there’s no back-and-forth with multiple installers. You get our unbiased opinion to help you make the best decision for you and your family!