Solar Panel Cost
The Solar Panel Cost is more than just buying the cheapest panel.
You can use Solar Power even in Lapland © mararie/flickr
First, Solar Panels are not created equal. They differ in quality, technology, usage, make…
And your house will be different from mine. You have x m2 or sq foot, mine has y.
So your question: “I have a 3.000 square foot house. How much is that in Solar Panel cost?” won’t help us.
Your house will also be in a different region on this planet. You get more or less sun than I do. You heat more or less than I do. You have a pool and I do not (not even a pool solar heater 🙂
So not want to bore you, I guess get the picture: But you may have an A/C – and I don’t…
Solar Panel Cost depends on demand
So to calculate the solar panel cost we have to know how much electricity you actually need … and how easy it is to produce…
So let us begin with how much you actually need…how much electricity is needed to keep running your home?
Take your utility bill. In Germany you get one per year, so you have to divide the total power used (kWh per year) with 365…voilÃ¡, this is your daily consumption.
In the US you probably have a monthy bill, so divide the kWh by 30…and you know your consumption, too.
Ok, done? How much do you need?
Solar Panel Cost depends on Where you are
Now we have to find out how many and which panels you need in order to be able to produce that much kWh on an average day. It’s that easy.
You do know how much electricity you need every day, now divide that by the average daily sun hours in the darkest months.
Now multiply this number with 1.15…this will give you a good number how many Watts of Solar Panel you will need.
Let’s say I need 10 kWh (10.000 Wh) per day. In the darkest months there are about 5 hours of sunlight a day.
So with out little formula I should aim for 10.000Wh /5h*1.15 = 2.300 W
I should be prepared to buy solar panels with at least 2.300 W.
To make this calculation even more accurate there is a great tool provided by the US National Renewable Energy Laboratory, or short NREL called ‘PV Watts’. It helps you to determine how much solar potential you can expect in your area.
So now I am trying to get the information for Hamburg, Germany. So I choose Hamburg and get the Weather and GPS data for – by the way – this beautiful city.
Then it is up to you to change some variables to get your result. And it is a bit of a catch-22, because you have to have an idea what your future solar panel’s specs will be…
Like the DC Rating. This is the nameplate DC power rating of your potential solar panel. So you have to decide how much nominal nameplate Watt you are going to buy. So if you buy (or plan to for the sake of a calculation) 10 panels with 100W each you buy 1 kW.
The next head scratcher is the so called ‘DC to AC Derate Factor‘… yep… Clear as daylight, isn’t it? 😉
Well, this has to do with the fact that your electric devices will insist on AC – alternating current. This is how our electrical society is using energy.
The sun produces DC – direct current. So you have to transform DC to AC in order to run your home on Solar Energy. And this ‘derate factor’ is kind of frictional loss while converting DC to AC.
So I am no engineer, only an economist so I cannot explain this factor better (please fell free to add your version below 🙂
Then you have to decide on the type: Are your going to follow the sun with the panel, so that it gets all the light available or is it fixed? And if you are tracking, will you be using one or two axis?
Then you have to enter the tilt – your latitude by default – and Azimuth. But the program gives you default values… so don’t worry.. all you do in the end is describing how your will be setup…
The last thing to do now is to use the default value or enter a number for energy cost/kWh…
Now press ‘Calculate’…
What comes up then is a calculation based on your planning.
For my 10 panels with 100W each and a fixed tilt in Hamburg I get this result:
Solar Panel Cost Calculation
ResultsMonth Solar Radiation(kWh/m2/day) ACEnergy(kWh) EnergyValue(euro) Jan 0.81 16 2.49 Feb 1.80 37 5.75 Mar 2.94 66 10.26 Apr 4.24 95 14.76 May 4.77 105 16.32 Jun 4.43 92 14.30 Jul 4.15 90 13.99 Aug 4.10 89 13.83 Sep 3.09 66 10.26 Oct 2.06 45 6.99 Nov 1.26 26 4.04 Dec 0.63 11 1.71 Year 2.86 738 114.69
So what we can see is that based on my plan to buy 1 kW worth of Solar Panels I can substitute at least 11 kWh of electricity per day in the worst month, December.
If you live in Tampa, FL or Melbourne, AUS and/or use a different and tilt you will have completely different results.
The same assumptions for example for Tampa, FL, give you a daily electricity harvest of 95 kWh. Nearly 9times as much…
So living in Hamburg I will have higher cost of solar panels than in Florida, because I need more power capacity.
Since I already calculated how much electricity my home needs every day, you have to adopt the panel size until you will produce more energy per day in the worst month than you would need.
And do not forget these are average numbers.
The month you will produce the fewest solar energy will be the month you will need the most power for your lights.