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Reading Your Solar PV Installation Output Results with the OrxaGrid Low Carbon App

Today we are sitting down with OrxaGrid's Data Analytics team to discuss how to read your results for the Solar PV Installation Outputs.

The OrxaGrid Low Carbon App will help you optimise the size of your proposed Solar PV Installation.

This app is provided on Microsoft AppSource and made available through the Microsoft AI for Good programme.

If you want to read about how to use the OrxaGrid's Low Carbon App, you can read about it here.

It's important to remember that these results act as a planning guide, so make sure you consult us or an accredited installer before installing solar.

A Guide to Reading Your Results


Here is a link to the OrxaGrid Low Carbon App.

The output results show your ideal system size and the financial benefits were you to install solar.

  • Annual Benefits

  • Optimal System Size

  • Utility Bill Saving

  • Payments from Export

  • Estimated Installation Costs

  • Lifetime Benefit

  • Lifetime Profit

  • ROI (Return on Investment)

  • Payback Period

  • Optimal Size Curve

  • Import/Export

  • Sample Week


Annual Benefit

Annual Benefit

Annual Benefit displays the sum of how much you could save annually due to lower electricity bills and how much you could earn through the export of electricity to your utility should you get the recommended solar size.

The output displays a single value for the entire year. Currency isn't specified as it is determined by the currency values you put into the form (eg. if you enter your values in USD or GBP, it will be displayed accordingly).

In the screenshot example, the annual benefit comes to £1,567 for the inputs we entered for our south-facing, 30-degree roof location in London with an import utility tariff rate of £0.14, the export rate of £0.04 and system installation cost per unit (kWp) of £1840.


Optimal System Size

Optimal System Size

Optimal System Size tells you what solar system rating you need in order to maximise your financial benefits.

Solar electricity systems are given a rating in the unit of Kilowatt peak (kWp) as the unit is the rate at which the system generates energy at peak performance. The kWp of a system takes into consideration the inputs you provide such as how much area is available to accommodate the panels, how much a typical installation costs (Cost per kWp) in your area and how much energy you consume at your location. In our example, we get an optimal system size of 13kWp.


Utility Bill Saving

Utility bill saving

Utility bill saving is how much you will save each year as a result of paying less in utility bills.

The model takes into account your utility tariff rates and the amount of energy your solar installation would produce throughout the year. Our example shows a yearly utility bill saving of £1,343.


Payments from Export

Payments from export

Payments from export are what you could earn by transferring excess unused electricity that your solar setup produces back to your utility.

This is, again, displayed in the currency values that you selected in your input form. You would need to check the regulations in your area to see whether your utility can pay you for the unused energy generated by your system. Our example shows a yearly payment of £223 for electricity export.


Estimated Installation Costs

Estimated installation costs

Estimated installation costs are the total costs that your installer would charge you for installing the solar system of the recommended optimal system size.

This is a multiplication of your optimal system size as recommended by our model and the System Cost per KWp that you entered in the input form. Your installer may charge this amount up front or spread it across the length of your contract. This tool gives you an idea of what your costs could be. In our example, we entered the per-unit system cost of £1840 and our Optimal System Size was recommended to be 13 kWp. Thus, we see the Estimated Installation Cost as £23,766.


Lifetime Benefit

Lifetime Benefit

Lifetime Benefit is the total financial benefit that you will earn (not adjusted for inflation) over the expected life of the system.

The expected life is assumed to be 20 years unless you entered a different number in the input form. The unit here is the local currency that you selected in your input form. The lifetime benefit is simply your Annual benefit displayed previously and multiplied by the expected life of the system.

In our example, we get a Lifetime Benefit of £31,333 which is the annual benefit of £1,567 multiplied by our expected system life of 20 years.


Lifetime Profit

Lifetime profit

Lifetime Profit is the difference between the Lifetime Benefit and Estimated Installation Costs displayed in your local currency.

In our example, our Lifetime Profit of £7,567 is the difference between £31,333 and £23,766.


ROI (Return on Investment)


ROI is the ratio between the Lifetime Profit and the Estimated Installation Costs.

A high ROI means the solar installation's gains will compare favourably to its cost. ROI can be used to evaluate the efficiency of your investment or to compare the efficiencies of several different investments. In our example, the ROI is 32% calculated as (£7,567 / £23,766)*100.


Payback Period

Payback period

The payback period is the time in years required to recoup (or reach the break-even point) the Estimated Installation Costs were you to install the recommended solar setup.

Our example shows a payback period of 15 years as the time required when the annual benefits of £1,567 add up to at least the estimated system cost of £23,766.


Optimal Size Curve

Optimal size curve

Optimal Size Curve is a chart to show you how your annual profits (Lifetime profit divided by the expected life of the system) in your local currency will vary depending on the size of the system.

As you can see in our example, the annual profit is the highest when the system size is 13 kWp. The annual profit for the 13 kWp system comes to £378 (Lifetime profit of £7,567 divided by the expected system life of 20 years). This is why our model recommends the optimal system size as 13 kWp.




Import/Export is an interesting visualisation to see how your energy use changes throughout the year.

The chart shows the total daily solar generation that you will get from your recommended system (blue line), the building load based on the energy consumption data you entered in the input form (yellow), the important energy i.e the energy that you will be buying from your utility (green) and the exported energy i.e the excess solar that your system will send back to the utility (red). All the four lines are displayed in kWh which is the unit for energy.

In our example, you can clearly see that our 13 kWp solar system will export quite a bit of electricity in the summer months when the sun is shining and our building consumption is quite low (we don't need a lot of ACs in London yet!). However, in the winter months, it's quite the opposite. We will be using almost all of the solar power our system will produce and still have to get energy from our utility (as it's not so sunny here in London during the winter).

An important point to note here is that you can see the most energy our location needs during any hour is around 24 kWh (look at the high green and yellow lines in June). Yet our model doesn't recommend us to install a 24 kWp solar system. It smartly calculates 13 kWp to be the most financially viable system by taking the entire year's energy consumption seasonal usage into consideration.


Sample Week

Sample week

Sample Week displays the consumed, generated, imported and exported energy in kWh. This is a higher resolution snapshot of the information displayed in Import/Export and allows daily patterns to be visualised.

It can be seen that solar power is generated only during daylight hours and that when the building consumption is low some of the generated power is exported.


Subscribe and come back to find out more about new app features, improvements and the essentials of using the Low Carbon App.

Thoughts? Feedback? Join the conversation in our comments!

OrxaGrid is an IoT and data analytics company that is on a mission to enable a reliable, affordable and sustainable energy future for all.

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