Which way should my solar panels face: south or east-west?

There's been quite a bit of news lately regarding the installation of solar panels on 500,000 buildings in the UK, suggesting that the panels may be facing the wrong direction! A leading solar expert, professor Ralph Gottshalg of Loughborough University, made the news this past week when he said that thousands of well-meaning people in the UK have installed their panels the wrong way. According to the The Telegraph in the UK, Professor Gottshalg  "is urging the UK to follow Germany’s recent policy of putting panels on east-west facing roofs to smooth the supply of power during the day and prevent spikes of power at midday."

Traditionally, solar panel installations (in the northern hemisphere) have been oriented such that the panels face south, to soak up the maximum amount of solar energy during the middle of the day, when the sun is at its strongest. But in some cases, that can create a surplus of energy that goes to waste. More and more, people are considering the advantages of orienting their panels such that they meet the demands of the peak energy consumption hours, in the morning, and even more so, in the late afternoon and evening.

What is the best way for you to orient your solar panels? Well, that depends on a few things!

Is the energy for personal use or for selling back to the grid?

If your panels are for generating energy for your own personal use and you are not selling the energy back to the grid, then you need to consider when you consume the greatest amount of energy and whether you have a system for storing your excess energy. If you're off the grid with a cabin in the woods, for example, and you have a battery to store your energy for use after dark, then you may want to stick with south facing panels to maximize your midday energy generation. But if  you're simply trying to reduce your monthly electricity bill by generating some of your own power, or if you're an investor selling back to the grid, then you may want to consider the times of peak energy consumption, which are often reflected in higher energy prices, and maximize your solar power generation to coincide with these times. An east-west installation (or simply a west-facing system) is gaining more and more traction in the solar world. In Germany, with the recent shift in policy, east-west systems are already a reality at the industrial scale, as can be seen in this mega-watt scale project at Holzengraben.

Does your utility pay/charge more during peak periods?

The cost of electricity where you live is an important consideration, whether you are generating power for personal use or whether you are selling back to the grid. Obviously, in both of these cases, if you live in a state or province where your utility prices change according to the time of day, you want to maximize your investment by generating more energy during the peak periods when energy is most in demand. In the province of Ontario for example, a majority of electricity users pay time-of-use prices, corresponding to three prices, one for off-peak, one for mid-peak, and one for on-peak demand, ranging from 7.5 cents per kWh to 13.5 cents per kWh. An east-west system might serve you better if you're paying more for electricity just when you need it, in the afternoon and early evening. It's important to check the details of the net-metering or feed-in tariff agreements that are in place where you live.

Let's run the numbers: Loughborough, here we come!

So what does WhatNextNow Solar Discover have to say about the orientation of the panels? Let's visit  Professor Gottshalg's university town of Loughborough and run the numbers. An averaged-sized solar power system of 5 kW, facing south, is expected to generate about 4700 kWh of electricity per year at this location. If we lower the inclination of the panels (say to an angle of 10 degrees from horizontal) and point the panels west, the estimated generation drops to about 4200 kWh. It is clear that we lose a little more than 10 percent of our annual production, but not all kWh of electricity are created equal. If there is time-of-use pricing in your area, east-west facing panels will generate more electricity during peak demand hours, resulting in savings that can easily offset this 10 percent loss on an annual basis.

In conclusion...

Whether you have a south-facing or an east/west-facing system, you're still doing yourself, and the planet, a favor by generating your own electricity through solar power. If you have yet to install panels, consider your options - you can start by checking out WhatNextNow Solar Discover and playing around with the orientation feature to see the impact of different facing panels. With Discover, everyone can find out what they could be producing in terms of solar energy if they had their own system. Aren't you curious?