The Global Solar Atlas Website

While I was researching SolarPV systems, I came across the Global Solar Atlas (GSA) Website which purported to tell me (in great detail) what kind of performance I could expect to get from the system that was being proposed. The more I look at this site, the more I am impressed. So far, my actual results have agreed to a high degree with its calculations of what I could expect to generate.

Another interesting detail relates to the optimum tilt angle for the panels. In most residential installations, the owner does not really have a choice of the angle at which the panels are mounted. If the panels were on a frame mounted on the ground or on a flat roof then there would be a choice. However, in most residential installations they are simply mounted on whichever roof points south-ish (north-ish in the southern hemisphere). The panels are tilted at whatever angle the roof happens to be.

That does not mean that optimum tilt is not interesting though.

Although you might not use data on GSA Website to go out and adjust the tilt angle of your panels - you CAN see at what time of the year they will be most effective. On lots of Websites you can put in your locations and find an optimum tilt angle to maximise the total solar generation for the entire year. But if you think about it, even if you WERE setting the tilt on a frame, you would not necessarilly want to maximise total generation. To my thinking, it would be better to maximise the output for the time of year that you are most likley to benefit from free power. That could be for winter heating or for summer air-conditioning.

It turns out that my 30 degree roof will give me my highest output in May, June, and July with only slightly less in the month either side of this. This is interesting because it would seem, from reading other Websites, that the "optimum" tilt would be about 62 degrees in winter and about 16 degrees in summer. If one WERE adjusting the tilt, it would be interesting to put different angles into the GSA Website and look at the seasonal graphs - rather than relying on some "optimum" figure.

Here are just a couple of the charts generated for my site on the GSA Website:

You may be interested in comparing the results from another, similar, Website: The Photovoltaic Geograhical Information System, from the European Commission. In my case, the results were very similar to the GSA figures.

Comments

Post a Comment

Popular posts from this blog

Automation tasks underway

I have the following automation tasks underway, in various stages of completion: If there is a suitably inexpensive timeslot overnight, use it to top up the batteries to 100%. Using this, instead of solar, will allow more solar to be exported at 15p/kWh. Inexpensive slots during sunlight hours are not as useful because I can't export at the same time as using electricity from the grid. If there is not a suitably inexpensive timeslot overnight, top up the batteries from the grid during the period coming up to peak time (which is usually fairly reasonably priced). Make sure any battery charging from the grid is definitely off before the 4pm-7pm peak rate starts. When the electricity price goes negative, boost the hot water temperature using the heat pump and immersion heater. This is a way of benefitting from being PAID to use electricity and storing a little of it in the form of hot water. Change the colour of a lamp in the kitchen to reflect the current electricity
Read more

No, YAML ain't, but what is it?

YAML is said to stand for "YAML Ain't a Markup Language". This unhelpful acronym (and brazen use of the old "GNU = GNU is Not Unix" joke) doesn't really help in understanding YAML as it pertains to Home Assistant. Well, in this context, YAML is a way of defining the hierarchical configuration settings that drive Home Assistant. So, suppose we have some settings such as: Lights: Left: Brightness: 4 Colour: "Red" Right: Brightness: 6 Colour: "Green" Fans: Extractor: 2 YAML is just the thing to define such a hierarchical structure. For the moment, don't worry too much what these might represent. Consider, however, that we might want the actual settings (such as 4 or "Red") to be controlled by some variable quantity derived from something else within the system. In this case it would be useful to be able to replace the settings with snippets of Python code. And this is, effectively, what H
Read more

A new strategy, a new approach to automation

As I explained before, I was very wary of automating my system beyond what the inverter could do natively. As a retired elecronics and software engineer there is too much danger that such an endeavour would become a slippery slope. Well, I now have one foot on that slope! What prompted this change of heart? Well, during the last month we had some periods with VERY low Agile prices and it got me thinking about how I use my generated solar power. One way of looking at it is to look at the "opportunity cost" of the solar power generated. The incoming solar power, thanks to the sunk cost of the system, comes in at 0p/kWh. However, I can sell any excess back to Octopus at 15p/kWh. That means that, effectively, any solar that I use is costing me 15p/kWh - inasmuch as I could sell it if I want to. This way of thinking leads me to consider a different strategy: What if I were to charge my batteries on a cheap rate at night and, during the day, export most or all of my solar at 15
Read more