OpenSolar Review - fast, precise and free

Get an indepth look into OpenSolar - free solar design software built for solar installers all over the world.

February 2, 2023
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Get an indepth look into OpenSolar - free solar design software built for solar installers all over the world.

Lucian Wu

The following is a review as per the date above. There is no exchange of compensation and there are no affiliate links on this page. All opinions are my own.

OpenSolar is a cloud-based solar design software built for installers all over the world. It is easy to use, quick to design, and calculations are accurate. 

It is no wonder that they are one of the fastest growing solar software in the world.

But the biggest selling point is that OpenSolar is free. Free for all users with unlimited projects, with no ads. Hard to beat that isn’t it? But is it really free? We dig into it in a bit more detail later in the article.

It is an excellent product for startups and established solar companies. Here's our article for the best solar design software.

If you want to lower your operating expenses by integrating OpenSolar with your website, CRM, XERO, etc, please book a time.


  • Free. 
  • Designs are fast and accurate
  • Customisable proposal templates
  • Lead Generation form


  • Nearmap is not included
  • User interface feels outdated
  • Waiting time for some pages and PDF generation feels lengthy

Why OpenSolar is free

Let’s address the elephant in the room. 

How is it possible that a for-profit cloud based software company OpenSolar is free. How does it make its money?

In this video, their co-founder, Andrew Birch, explains how OpenSolar Solar generates revenue. They charge their partners instead of solar installers. 

Here are their partners shown on the website. They look like a collection of some of the world's largest manufacturers and lenders in solar. 

I like the direction they've taken. It's unconventional, but effective. I wonder why other solar solar software have not done the same. Fingers crossed their business model continues to work.

But OpenSolar is not *completely* free

There is a hidden cost to using OpenSolar. It is the disadvantage of using Google Maps as the default maps service.

We’ve all used Google Maps to get from one place to another, or to check traffic. 

But being a solar installer, you need a clear picture of your customer’s home. Your neck is on the line here. You need to be 100% confident of your roof and surroundings before you can give a quote. 

In this case, you may need a maps service that is higher resolution and is updated more frequently - NearMap. 

Nearmap costs around $250 a month, but their images are much clearer. 

In comparison, Solar Proof includes Nearmap as part of their packages.

NearMap achieves this by taking photos from a plane and publishes them at least once a year. Google Maps takes photos from a satellite, and could take 1-3 years to update.

Below is an example of the difference between the two services. The image on the left is Google Maps, and the image on the right is from Near Map.

Nearmap 2023 Update

OpenSolar and Nearmap have updated their integration, and they now allow Pay-Per-Projct for nearmap. This costs around $6 AUD per project, and is ideal for smaller solar installation companies that will quote fewer than 30-50 jobs a month.

The instructions on how to do this is found here.

User interface is functional but feels outdated

Improving the user interface (UI) would go a long way to making life easier for the user. Currently, it works, but feels outdated.

This is what you see when you log in and are about to create a new customer.

It looks like a programmer designed this. Not a UI designer. Dashboard designs have improved a great deal in the last few years.

See my improvements at the bottom for what I hope OpenSolar's UI should look like.

OpenSolar’s design process is easy and fast

We have to give credit where credit’s due. I love how easy it is to design a solar system on OpenSolar.

One thing I look out for is how easy it is for the user to correct their mistakes. Sometimes you may add a panel too many, or accidentally put it at the incorrect location.

I found adding, removing, and changing panels to be very easy to do. 

We've all used software that is difficult to use. When we finally come across software that is easy to use, we realise what we’ve been missing. 

OpenSolar did what I wanted to do. I can't find any possible improvements to the design process.

Searching for products is great

OpenSolar claim to have more than 20k products in their database (I haven’t checked). But what I can confirm is that their search function is fantastic.

The search page will give results search terms which are inside product codes such as:

Longi LR4-72HBD-415M

Design gives option for stringing of inverters

Some of my clients use the stringing feature, and some don’t. 

So it would appear as though this feature is not critical. But it’s good that OpenSolar has included it for the installers that want to use it.

3D Design - looks great, but is it necessary?

It is obvious that the developers spent a great deal of time and effort to get the 3D imagery to work with the panels. And it looks great!

These images give customers the feeling of ownership before installation begins. 

But that’s all it is. A marketing feature. This may improve your proposal conversion rate. But will it improve your design accuracy? Would be great to test it.

Please comment below if you use OpenSolar’s 3D tool, and whether it has actually helped you.

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OpenSolar has an Application Programming Interface (API)

Using OpenSolar's API, you can collect form submissions from your website and push that data straight into OpenSolar and begin designing and quoting for your potential customers. 

The OpenSolar API documentation is here.

You will need to have some sort of understanding of a programming language to make HTTP requests, such as JavaScript or Python. Alternatively, you could use Zapier to do this automatically without any coding.

When a user submits the form on your website, the script will send the data to OpenSolar using the API endpoint for creating a new project. OpenSolar will then return a unique project ID that can be used to retrieve the project data and solar system designs.

OpenSolar’s calculations are accurate

To some solar installers, accuracy of the estimation is one of the most important aspects of the software. 

They don’t want to over promise the customer, but still want to present a good return on investment.

So I put OpenSolar’s calculations to the test.

I have access to data of a residential 8kW solar system in Melbourne that was installed at the end of 2020. It has been tracking energy data every day.

The system consists of:

  • 27 x 370W LONGi LR4-60HPH-370M
  • 1 x Fronius Primo 8.2-1

I used OpenSolar to recreate the exact same system with the same components.

This is a prime example of why Nearmap is critical. The panels have been installed for over a year, and Nearmap has updated its images, as you can see below.

However, Google Maps is still lagging behind, and so it seems as though solar panels have yet to be installed. 

The left image is the current image of the house at Google Maps, and the right image is the layout of the same panels designed by OpenSolar.

Following on, I then used OpenSolar to generate a quote, which shows its estimated daily energy generation.

I matched it against the actual generated data from the solar system from 01/01/2021 to 31/12/2021, 

Below is a table showing the OpenSolar estimation for solar vs the actual solar generation.

What this shows is that OpenSolar is extremely accurate with an error of only 7.17%. 

OpenSolar estimated generation vs actual generation

OpenSolar percentage error

OpenSolar actual error:

The error percentages seem high, but in comparison to other solar design software, I think this is extremely well done. 


There are no bells and whistles with the proposals. The proposal is a total of 7 pages (without datasheets), and is the perfect amount of information without being too salesy.

Here’s a look at some of the pages that are generated.

I like the general look and feel of the proposal. It’s clean and easy to understand.

However, there is only one design. This means that the more solar installers come onto the system and start generating proposals, the less that yours will stand out. 

In addition, there is quite a high amount of yellow in the proposal. Probably because OpenSolar’s logo is yellow. If your logo or branding does not contain yellow, your customers may feel a loss of consistency in your branding.

Customising the proposal (a little)

OpenSolar gives you the ability to upload your logo, move the pages about, and change the copy.

You're also able to change the color highlight of your proposal. This will most likely be the same colour as your logo.

Lead capture form on website

I love this feature, and I wish other solar design software can also implement this. 

OpenSolar give you the option of form on your website that looks like this.

Once the user inputs in their information, your customers tab in OpenSolar is automatically populated with their details.

All you have to do is paste a piece of code that looks like this:

Not only does this save time, it reduces human error. You don’t need another person to wait for leads to come in, and then manually enter the fields into OpenSolar. 

Can’t customise branding

The only gripe I have with it is that there is no way for us to customise the look of the form. All forms on your website should have the same branding. Even if the form fields are different. 

A form that looks different is going to stick out like a sore thumb. 

Possible improvements:

Here are some features that I hope OpenSolar could improve on in the future.

Improvements to their API

The OpenSolar API could do with tiny improvements to make it easier for users to interact with it. These could include:

  • Easier way to generating a token
  • Backend access to create and change webhooks

Integrations with accounting software

I would like to see a payment link included within the proposal. This would make it easier for your customers to pay, and for you to verify that payment.

Xero (or a similar competitor) offers this feature. 

Would be great to see some sort of integration in the future.

Integrations with lead generation tools

OpenSolar could make it easier on solar installation companies by providing direct integrations with lead generation companies. This means when you buy solar leads, they go directly into OpenSolar.

Its not natively integrated now, but if this is something you need, then book a time to have a chat with us.

Make OpenSolar *truly* free

I would love to see a day when OpenSolar offers their design software with NearMap for free. That would be the icing on the cake.

Update User Interface

Below are some examples of the latest dashboard interfaces. Let’s hope that OpenSolar updates their dashboard so that it makes your life easier.


Opensolar is a simple to use solar design that allows for all types of solar professionals to use. The best part of OpenSolar is that the use of their whole software is free. But only on Google Maps. 

So this only helps early stage solar installers who can’t afford to pay the premium of Near Map. 

For the more established solar installers who can, OpenSolar is a great design software that is simple to use and accurate with their estimations.

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