In my free time (I don’t have much of it), I like to free my mind from mundane matters and give myself to think like an engineer, to create something from scratch.
At my estate, the balconies of the last floors of flat the blocks have extra roofs. They serve as protection or like cover against rain. The lower floors usually do not have those “roofs”, the balcony of the neighboring apartment above has such a function, walking between blocks here and there you can see, that the owners of the lower floors apartments are building these roofs anyway – yes, they works really as extra cover for balcony. Overall, it improves the protection against rain and to much sun during hot summers. Also it is good cover against strong wind and protect things left on balcony, that could move wih the wind 🙂
In 2017, looking at these balcony with extra covers, I came up with the idea to construct such a cover but made of PV panels, so that the cover can give extra functionality and produces electricity. After a while I wondered if it would pay off for me? Will PV panels produce enough energy to pay for the investment within a reasonable time? And many other questions that I will skip here and which must be answered – I found.
First of all, I have all the necessary permits, allowing me to construct prototype PV installations and other renewable energy sources. I felt confident and started working.
After gathering most of all necessary information, I calculated how much I could produce energy with time, after my investment will return for my location. It turned out that my installation will return in about 3-4 years. I emphasize – my PV installation entirely designed and made by me, for my location. I did not take advantage of any subsidies or other funding, in 2017 and 2018 there were none :/ I’ve paid everything from my own private money. Please bear in mind that the payback period for a new installation site, which the contractor will build today for a fee, will look completely different – it’s for those who are firing, to cool them down a bit 😉
I thought I’d carry out a simple test before investing more money. I bought a small 20 [W] PV panel (nominally) with a simple PWM battery charging regulator for less than 200 PLN (around 47 EUR) with some very popular sell/buy portal in Poland. The package and shipping fee was free (read: included).
In August 2018, I mounted a PV panel provisionally on the window sill of the balcony and connected the old acid battery from my SAAB (SAAB received a new AGM battery). The whole August and autumn 2018 and the winter season 2018/2019 + spring 2019 the panel worked as much as possible, with illumination my balcony as I have. The southern direction is mostly exposed, only the SE direction is partly shadowed by the neighboring block. From April to mid-October, the neighboring block does not bother at all. The sun rises at a fairly sharp angle to my block and is already high enough, to illuminate my balcony very early in the morning and continue all day without shadows. It hides behind my block around 16:00 (in spring-autumn).
All the time this small PV (20W) was able to produce so much electricity, that it was enough to charge 5 smartphones (including two very power-consuming Windows Phone), two tablets and I still had a slight surplus. Personally, I was positively surprised by this result.
In the winter, this small panel could no longer produce enough electricity to cover the needs of all smartphones and tablets. It only could power of two smartphones. It was predictable but it didn’t discourage me. I estimated that a PV 200 [W] installation (10x more efficient) nominally with a good MPPT controller should successfully meet the winter energy needs of all smartphones, tablets and there will still be a surplus going to the battery.
I started detailed planning of the final PV installation, which was to cover the roof of the balcony and at the same time, the production of electricity in the Off-Gird system (at that time only the owner of a large PV installation could become a consumer and have the benefits of the On-Gid installation to the network to collect later minus 20% free of them of the power operator). I assumed that I would consume all the electricity produced from the installation and the surplus will go to the battery, from which I will draw electricity in the evening and overcast days.
Apart from the whole long history of building the target installation, I am summarizing, in this long description that I have finished my job and the production of electricity is better than I could expected, even now in winter 🙂
Few “words” about the PV installation itself.
The installation acts as a balcony roof cover against wind, rain and sun during hot summer and in addition produces electricity, which I mentioned above.
Each PV panel can change the angle of inclination to the sun to a limited extent. Thanks to this, at any time of the year, you can adjust the angle of the panel to the incidence of sunlight to increase efficiency of installation.
I buffer the surplus power current in gel batteries 4×80 [Ah] = 160 [Ah], connected in parallel. I made the installation in 12 [VDC], because the result of my analysis told me this iwll be best to my needs. The PV installation itself consists of 4 pieces of 50 [W] nominal PV panels, connected in parallel + charge controller. The panels are secured in such a way that the electricity produced by the illuminated panel, does not power the neighboring panel, which is just shaded (in winter the sun shines part of the day from behind the trees, unfortunately) and goes to the battery not to shadowed panel. Of course, the installation is current protected in different ways, I did not save on security and safety. I’m monitoring the work of the installation with my own solution based on Arduino chips + Web application, which visualizes the work of the installation. All software is my authorship.
My wife noticed that when it rains, things left on the balcony are mostly dry, just such a nice addition of my PV installation 😉
At home, nobody uses factory chargers for smartphones and tablets. I constructed my own power distribution point for such devices. The laptops are charging and are powered by a 300[W] converter produced in Poland. The surplus of produced electricity goes to the batteries, from which I consume electricity with home LED lighting in the evening – I separated the power line.
Cost of PV installation (equipment) + 230 [VAC] 300 [W] converter: 1800 PLN gross excluding gel batteries, which I was able to purchase with a very good discount price. I intentionally do not give them the cost, because for each installation a different buffer will be required. If so, the prosumer program published by the government are not covering small PV installations like mine. When they will and there would be funding … I am ready to join it by producing green energy for network. Today I consume everything I get and I’m already working on it to reduce electricity bills.
Below are some photos of the installation and application monitoring its works. I realize that many things I could have done differently and professional PV installers will point with finger at my mistakes, but in the end it is a prototype and there is a fashion for PV 😉
Installation power production graph for today’s cloudy day – 18/12/2019. Measurement every 20 [s]. One panel is better inclined to the sun than the others – I’m experimenting. Unfortunately, in winter half of the sunny time is obscured by the neighboring block :/ later around 13:30 CET the sun passes behind the trees, which also reduces the overall efficiency of the installation. Unfortunately, at this time of year, the sun is very low and the trees in front of my block are high. Maybe the administration of the estate will someday reduce them to a level below the winter sun horizon.