Originally published on Forbes.com on November 20, 2021

Studies show it is profitable to install rooftop solar everywhere in the US and Canada. Also viable is to electrify heating with a combination of heat pumps and solar PV, as studied in both Michigan and Ontario

Dr. Joshua M. Pearce is the Thompson Chair in Information Technology and Innovation at Western University in Canada. He has written hundreds of articles on solar energy and received a Ph.D. in materials engineering from the Pennsylvania State University for his work in low-cost solar cells. Pearce is the co-author with Lonny Grafman of the free, opensource e-book To Catch the Sun, a guide for making your own solar photovoltaic systems.

I emailed with him recently about build-your-own solar, Biden’s climate goals, and what the path ahead looks like for greening the grid.

Fossil fuels produce 83% of the world’s energy and 73% of the world’s greenhouse gases. How best can renewables like solar and wind change this picture?

Solar and wind energy are already often the lowest cost producers of electricity and when they offset fossil fuels they help to cut down our greenhouse gas emissions. Large companies – think Google, Apple, Ikea and Walmart etc. – are investing heavily in renewables – to help with greenhouse emissions in part but really to make more money. Even small businesses and homeowners can get in on the action when they start thinking of solar photovoltaics (PV) technology as an investment. A solid 25-year low-risk investment.

Biden’s goal is to produce 44% of the nation’s electricity using the sun by 2050. How feasible is this?

This goal is well within reach technically and the return on investment is there, but people need to update their mental images of solar. Solar prices have dropped so far recently that all the old assumptions about them are simply wrong. The electric grid is quickly evolving into a distributed system where we will all be both consumers and producers of electricity – and as electrical vehicle ownership continues to increase we can even offset expensive electric storage for the grid.

Source: Joshua Pearce.
What is the current market for solar in the US and Canada, and are government incentives needed to accelerate these renewable energies?

It is actually profitable to install solar pretty much everywhere in the US and Canada today. We did one careful study looking at every utility, rate structure, and potential solar system in cold, cloudy Michigan, and found everyone in Michigan would profit by installing solar. Things are obviously even better for solar in Hawaii.

Even more non-intuitively we found you could profitably electrify heating with a combination of heat pumps and solar PV in both Michigan and Ontario. The solar actually subsidizes the electrification. Government incentives are not needed, but still may be a good idea for accelerating adoption. For solar electrification of heating, for example, home owners would earn a higher ROI than they are getting on their bank accounts or bonds, but not more than their average stock market return. Solar by itself gets you higher returns and even double digits are possible depending on the locations solar flux and utility rates.

I’ve heard that Australia (pop. 25 million) has more rooftop solar installations than the USA (pop. 320 million) does. How can this be?

Great point! There are a few things holding the US back from its potential in solar. Many electric utilities have started to treat their customers as market rivals and actively try to prevent them from installing solar. They have manipulated rate structures and in some of the worst cases simply denied distributed generation from connecting to the grid. This is the exact opposite of what they should be doing to reduce the costs for all customers while greening the grid. In the US, the value of solar generated electricity from rooftop solar is much higher than the utilities are paying for it.

Treating customer solar as a threat is an antiquated way of thinking – and utilities run the risk that both homeowners and small businesses simply grid defect to make lower cost solar electricity for themselves. Smart utilities will work with their customers (e.g. funding solar for them as for example part of a roof leasing program) to drop costs for everyone while solarizing the grid.

US regulation of solar is also a mess. This is clear when you look at the total installed costs of solar in Germany vs the US. Germany has higher labor rates and yet their solar installed costs are much less than the US costs. If we had national standards like Germany, it would be much easier to scale solar and drive costs even further into the floor.

This has all slowed adoption of solar in the US.

Source: Joshua Pearce.  

Your book To Catch the Sun is about making your own solar panel system. That sounds complicated. How does DIY solar work?

Starting small with DIY solar and putting together a basic solar system is actually pretty easy and I would go so far as to say fun. To Catch the Sun walks you through it step by step with easy-to-understand mini spreadsheets and transparent calculations. You start by choosing the electric loads you want to solar power – maybe on the small side a smart phone all the way up to your house. You then determine the amount of power and energy you will need to cover the load, if it is AC/DC or both, and if you need storage or not. Then our spreadsheets help you calculate the materials you need and diagrams show you how to hook everything together.

For small systems you can do it all yourself. Making a small DIY solar system is just one step up of complexity away from following Lego building instructions. For larger systems – say to power your house – you will still need to do permitting in most areas and have an electrician do your final grid connection.

What are the challenges and rewards about building your own solar system, then using it?

The largest challenge I think for most people to do a DIY solar system is simply lack of electrical knowledge. Electricity is sort of black box magic to many people. I still think electricity is magical, but we open the box in the book by explaining all the terms in everyday language. We also share lots of examples from people all over the world building their own systems – to hopefully get through the idea that “you can do it too”. For small systems, say you want to do a solar-powered security light – it is truly easy. For systems that interact with the grid, learning and following the regulations for your area is the hardest part, because every utility and jurisdiction often has their own rules. For these systems you need a professional for the final tie in.

Many people get a great sense of accomplishment making solar systems themselves. They also save a lot of money and can often have power for applications that would be impossible or cost prohibitive to do in other ways. To help people do this – we are literally giving the book away for free – anyone can get a free digital copy HERE. You can also get it in paperback from your favorite bookseller and all proceeds go to the Appropedia Foundation to ensure that content is always free and up to date.

Poorer communities are strained by energy costs. Can build-your-own solar help?

Yes absolutely. Building your own system radically reduces the cost of solar so that it can be accessible to people with very little access to capital.

How much money can a person save by constructing and installing their own solar panels?

It is pretty easy to cut the cost of electricity with a DIY PV system.

Let me give you two examples. Let’s say you are looking to use solar to power an electric device you currently power with disposable batteries. The best deal on Amazon now is about $0.40 per battery. Disposable batteries provide only a paltry amount of energy so the cost works out to $152.38 per kWh! In the US, the average cost for grid electricity is about $0.14 per kWh. So, if you can plug in your device that is the way to go. You can also build a small DIY solar system for the same device and power it for only $0.05 per kWh. So, if you replace grid electricity with DIY solar for your device you will save a lot of money and if you do a system to replace batteries you really obliterate the cost.

Let us say you want to power something bigger like your house. Solar power systems are quoted on a $ per Watt (a unit of power) costs.  In the US, most systems sold to home owners fall around $3/W installed and you might need 4kW (4000 W). This is a total cost of $12,000. You can buy a kit that includes everything for $1.75/W and do it yourself or buy the individual components and drop the cost well under $1.50/W so you save more than $6,000. It is pretty routine now to see individual solar photovoltaic modules selling for under 50 cents a Watt and good deals under 25 cents a Watt. The bottom line is DIY will cut the cost of your installed solar system in at least half.