CONVENTIONAL LARGE SOLAR SYSTEMS (Don't do it!)
After looking into specialist commercial UK energy company "approved" official PV systems, installing 1, 2, 3 and 4Kw solar systems at very high cost, to allow you to collect the governments "FIT'S" payments, as well as the "free" systems where you effectively lease out your roof for 25 years to get the free generated power for nothing, I decided it was all too complicated, too expensive, or meant you no longer owned your own damned roof!
Now IF you have a huge roof, and about £7000 UK pounds burning a hole in your pocket it sort of adds up. But your money is then not available for other things. And year on year the amount of FITS payments gets less and less. It also makes it very hard to add more power or panels later on due to the way that these big systems work by connecting panels in series.
So then, way too big, too expensive or financially risky and lots of money tied up for 20 years. And now the UK government payments (FITS) has been reduced to very low level. So is no longer a guaranteed sensible long term profitable or worthwhile investment in the UK for many
The question I am trying to answer here, is this:
IS IT VIABLE TO IGNORE ALL THE OFFICIAL SCHEMES, AND BUILD A SOLAR SYSTEM YOURSELF ON THE CHEAP?
MUCH CHEAPER DIY
So I did some maths and had a look around. Its possible to buy cheap Chinese made "grid tie" solar inverters on eBay. These are not government approved so you cant use them to get FIT's payments. And they may even be illegal to use. If that bothers you then read no further! They "claim" to be CE certified however. It doesn't worry me, since I understand what I am doing and will test and measure everything to make sure that they are at least safe, and that they are making efficient use of the expensive panels I am buying! But they are cheap enough, 92 percent (claimed max efficiency) - we will measure this and find out for sure.
They very are simple to set up. Literally just plug them into any wall socket, connect up a Solar panel to them. You are done! This will generate SOME power even in winter or when there's no sun. (But not much! See later)
How much power will you get realistically? Not a lot! You need 2x or 3x 250 watt panels on your roof in the UK to make best use of these inverters, (these PANELS are about £140 / £150 each delivered) and a cheap 500 watt inverter (£70 eBay) to save you around £80 to £100 a year from your utility bill if these panels are in a good position.
The advantage is that you have a simple system, that you can add to later on as you wish, in small affordable stages. Once the cost of 1 or 2 or 3 panels and an inverter is long forgotten, and the ongoing bill has reduced, you can then just add some more panels, and add more inverters as you can afford them!
And keep on doing so, year after year, until you generate as much or more power than you use.
REDUCING POWER USED
This cheap eBay energy meter clamps over a wire in your electricity meter cupboard. Your utility company will give you one, or eBay... Sends a wireless signal to this display shown here. It reads the power used directly from my electricity meter. It shows that during this winter I am averaging about 13KW Hours every day. That's pretty average. This can be reduced quite easily. And I have gone some way towards this. And that I am using 626 watts as I type. 400+ watts of this is my PC! So I have just set up all its power saving options very carefully. That alone will knock off a great chunk of my bill!
And if you are careful with the power you use, avoid your 3000 watt clothes dryer, replace all your lighting with LED lights, set computers to low power mode etc; you can easily half your electricity usage. Get one of these energy meters fitted in your house asap! It takes minutes, and can literally half your bill. This will in turn PAY for your DIY solar system setup, easily in a couple of years just on power saved! Further reducing your expenses.
This is a combined approach. I have already done the power use reduction program above, and it was pretty painless! That alone HALVED my power bill. My daily usage measured on a wireless meter sat on my desk (pictured) has dropped to half of the original figure. Along with the bills. So now I only need to make HALF the solar energy. Once you see how many chargers or TVs you have sat on standby for E.G. 24/7 using approx 40 watts all day long doing absolutely nothing you will soon turn them off!!!
Remember that it is unlikely you will make more power than you are consuming, just slow the meters progress during the day while the sun is out. If you do make more than your house uses, most modern meters do not run in reverse, but most can count both power used as well as power returned to the grid. Although in this case you will be paid less per kW/hour that you return. Still better than nothing though! With this in mind it makes no sense fitting a huge 4kw system, and its probably best to add around 1 to 1.5kw system over time.
GET A GRID TIE INVERTER ON EBAY!
The photo is of a very cheap £70, 500Watt GRID TIE inverter.
This takes the DC low voltage power from your solar panels from 22v up to 62 Volts and feeds it directly into a wall socket at matching AC frequency and Voltage and matching waveform as your mains power.
This means that the power coming from the street is reduced by the amount the solar panel is producing, and so the utility meter runs slower.
Your fridge/computer etc will first use the power from your solar system, and if that isn't adequate will make up the difference from the grid/street.
This one I ordered, to play with and measure and test for you guys, is a 500 watt one, that outputs 240VAC for Europe. Actually up to 260V as it needs to do. Other sizes and voltages for 110/120 etc are available for the rest of the world. You can connect up to (600w Panel Watts) of solar panels to it, wired in parallel. Or more if you wish. So buy one panel this week, another next week or month as you can afford it. After initial testing with a bench power supply and some amp/volt meters to check efficiency and voltage tracking etc and to test the Islanding protection, I can say they work pretty damned well! And after testing a 250 watt 30V 250 watt panel, I ordered 2 more. Looking pretty good and more efficient even in low light than I expected.
They really do approach 90 percent or better. At least at high power levels. At very low levels like 10 watts, they are only about 50 percent efficient. Not that it matters a lot at these low levels. I have to add here that I have 3 now. And one "crashes" and needs a restart periodically. So typical Chinese quality control... Will keep that one for spares.
Flexibility. And you can plug in as many of these in your house or garage as you wish when you expand further... This cost me around £79 pounds. It does optimum efficiency point load/voltage tracking, and is both 92 percent efficient and simple to connect! Plug it in, and connect a panel. Or more panels. It tells you how much power is being generated, etc on the front panel.
Testing on the bench. This cheap inverter is idiot proof. Just plug it into the nearest wall socket, and connect your solar panel wires. Done!
SOLAR PANELS / PV PANELS
For this cheap eBay inverter you can have up to 600pW (panel Watts) or more. They do not overheat or die with too much panel power as you may hear on places like U-TUBE. Those guys are dummies. I have tested these with a full KW of panels on a 500 watt inverter for days in summer. They are just fine. But they top out at 450 watts OUTPUT. If you fit more, you run the risk of wasting the maximum panel output. But it will not happen very often in the UK! So I will use 2x or even 3x 250 Watt panels in total, for each 500 watt Chinese grid tie inverter.
It has a 22v to 60v input, and can work with most panels. Unlike commercial systems that connect up panels in series, this inverter wants you to connect them in parallel.
That's great! It means you can start with one panel, then add another later on. It alkso means SHADING one panel, has no affect on another panel, unlike the series connected commercial setups. You can lose about half the power on those if one panel gets shaded out of 10! So they make MORE power than commercial systems in shady or partially cloudy days.
I ordered 2 panels initially. These are 250 Watt, 30.1V working voltage (37v off load open circuit) and they cost me £142 each delivered. These are big, at 1660mm x 992mm wide. The third one will be ordered in a few weeks when I saved up more money!
You need to site these (in an ideal world) at approx 30 degrees from the horizontal in the UK, and pointed South. Other angles, and non south work too, but not as well. I can do this pretty easily as I can build a simple frame and put them on my flat roof. See pictures later.
The angle, or the pointing south, isn't actually as critical as you may expect. Laid completely flat on the ground, you lose about 16 percent of the daily output. Facing east or west is about the same, or slightly worse. But its really not that bad. So if you have an east or west facing roof, don't worry! Still worth doing. I may put some along my garage roof eventually and connect another inverter up in there and it faces east/west...
FITTING THE PANELS
A panel. 250 Watts. 37.4v Open circuit Volts, 30.1V Operational peak efficiency Volts. This is a conventional silver panel, that will be used at the rear of the house where it is unseen. I will use black ones for the front of the house, as they are prettier.
Panel actual specs, PDF file HERE these are the latest 250 Watt ones.
Mounting blocks for a flat roof. Growing them in my kitchen... Wet cement, and a trowel is all that's required to make cheap non blow away solid mounts! Told you I was cheap!
Before the cement sets, make sure the holes are the right distance apart! Note bar at the top. This is used to mark the panels for drilling too, so every panel is the same and interchangeable.
The ideal angle is south (as these are) but at 30 degrees to the horizontal, to give the best 12 month power collection power. But unfortunately, the sun is behind the rooftops in the winter months, so I mounted these at 20 degrees to maximise summer output. These will produce very little to no output in winter. Mounting: These are just hollow concrete blocks, and 50mm Angle aluminium strip, cut to length, cemented in place..
Also, note the higher flat roof in the background. This will have 3 panels installed too, as and when I can afford to expand this rather expensive experiment. These ones above will see direct sun in winter so should be more efficient. The ones on this flat roof that martin is assembling see shade in winter months. The ones on the higher roof will be set at a very low 10 to 15 degrees and in LANDSCAPE mode, so that they are almost invisible from the front of the house. But that's a project for the future. This may or may not turn out to be profitable long term. But readers, I can make the sacrifice here, paid for by these pages ads, so you don't have to try it!!!
The gap between them that Martin is struggling with is for airflow, (hot panels work worse) and to make it simple to get at the bolts, and give any wind an exit route. Only the weight of the concrete blocks holds the panels in place. But they are heavy. And cheap :) Like me. The 3rd panel, will go directly next to these two in the carefully measured space!
This single inverter is actually generating SOME power even with only two panels, in mid winter in the shade and its almost dark.
But not enough to be useful! About 5 watts.
It just literally plugs into the wall.
Eventually there will be more and bigger grid-tie inverters and a shelf or something with a door so they will not be on view.
There will be 4 separate Watt / amp / Watt/Hour simple plug in meters (eBay) to monitor exactly what each separate bunch of panels is doing in detail so I can see what is really going on and graph the results.
Now 3 solar panels. All are 250 Watt, 30.1v peak efficiency, 37.5v Open circuit in direct sun. These are connected in parallel, to one set of 6 sq/mm cables that go into the room below. 10sq/mm would be better. But more expensive. This is a short run so acceptable.
That's 750 watts theoretically in high sun. Or it would be in the Sahara in summer. In reality its nearer 600 in the UK at peak times maximum (I think).
I will monitor this, using some fancy metering to see if its going to pay for itself WITHOUT the Government payment scheme. Because I am not claiming anything from the government. This is an experiment to see if solar - done cheaply - is viable ON ITS OWN without government hand outs.
In total, I will have 10 panels eventually. This website is paying for it. So if it pays we win. If it doesn't pay we lose but not out of my own pocket... You got to love experiments and the internet!
When I add another 3 on the higher dormer bedroom roofs, and connect to another inverter then this will be a separate system but output will be double. Then a further 4 where you can see that picnic table in the picture below. And ongoing as finances and roof space allows. Its daft not to do so.
As you can see there's room for plenty more. In fact this roof goes further to the left than this image shows. But I am not adding panels here.
Panel actual specs, PDF file HERE - these are the latest 250 Watt ones.
There's actually room for another 5 along the far left edge. There is also room for another row in front of the first. This 2nd row will need to be at a lower angle or well in front of these, so as to not shade the existing ones. That would then be a total of 4kW system in the far distant future. If panels get very cheap!
The next 3 panels however, are not going on this roof at all. They are going on two higher up, flat roofs above the dormer bedrooms on the main roof behind me in this shot. Because they will see more sun in deepest winter, and be more efficient when the sun is low. The large flat roof shown here is shaded by the main tiled roof where these three initial panels are sited during winter for about 3 months.
Right now, on the shortest day of the year, in overcast rain conditions with a dark sky in shaded side of the roof it makes just 36.3 watts! That's a miserable 24.87v from these 30.1v optimum panels at the best output voltage. But even that is better than nothing. No sun, no power! If it falls just below 22 volts on the input, the inverter goes to sleep. No lights, and under .5 watt power consumption. It wakes up in the morning as soon as the panel reaches about 28v Open Circuit, which is the crack of dawn, and it then loads the panel in an attempt to find the most efficient voltage for maximum watts output. Pretty damned good for a cheap inverter!
Now there are 3. Each will be connected to 3 panels. So we have 3 wall-watt meters so I can see what each set gives me. And the green one has a battery. So it cannot lose its memory, and it adds up the total from all 3 as time goes on over the months and years. Right now, there are just 3 panels, and a total of 1.5 watts from the middle inverter since there's about 6 inches of SNOW on my panels...
In summer I expect these 3 panels to give me more than one inverter can manage. It has a 500 watt capability MAX claimed output and 600 panel watts as a "best fit" suggested. 750 should be better. (3x 250 watt panels).
There are 2 more unused, disconnected inverters in this picture. They are for the future. I intend to use more panels as I can pay for them via the income generated from this site to further investigate how well these Chinese DIY inverters and DIY solar really is.
I just took delivery of these BLACK panels, that will be used on the 2nd inverter. They look nicer than the silver framed ones, have the same electrical specs, are also 250 watts each. These will be seen on the flat roofs on top of the dormer bedroom, and dormer bathroom from the front of the house. So worth the small extra expense of the black solar panels.
These will use black plastic mounts, rather than the concrete blocks as they also look a bit prettier!
These are not cheap. But look better where they can be seen.
These three black panels will be connected in parallel, and feed inverter number two. This can only output 500 watts, but the panels can theoretically generate 750 at times. But most of the time in the UK it will be far less so shouldn't really be a problem and I will only lose out for a few moments now and again! The rest of the time the 500 watts each inverter can manage will be adequate.
Later on in the summer, I will fit another three panels, either on the flat roof at the back, or at the rear of the house on a stainless steel tubular frame to form a parasol where my BBQ and picnic table are.
That will be my 9 panels (2250 panel watts, connected to 1.5kW inverter power). The total outlay will be around:
9x £115 per panel (plus tax). 3x £69 for Chinese inverters. 3x £50 for plastic mountings. 3x £15 for "home made" concrete mounts on flat roof. And approx £150 for stainless steel mounting at the BBQ in the garden. And £100 for 6mm and 8mm cables.
DORMER ROOF PANELS
Here is two of the three Dormer Bedroom/bathroom Solar panels. These can just be seen from the road.
Closer... The third one cant be seen from the road easily...
But can be seen here. That's 3x 250 watt 60 cell panels all connected in parallel and connected with 10sq/mm cable. Its a long run and this is 30 amps @ 30.1Volts.
Now there are 4. These things are taking over the bench. They are spaced apart so that they cool well. Or the fans come on and this gets quite noisy. So that's 6x 250 watt panels, in two sets of 3 parallel connected. So only 1 and 3 are actually in use here. In winter sun, both arrays are making 300 watts give or take so around 600 watts total. Occasionally it goes higher than this. In thick white dull cloud (its January here and 2 degrees C) it makes just 60 watts. Roll on summer! So far this is a 1.5kw system. In summer I will add 3 or more panels at the rear of the house as a BBQ sun roof...
swapped 2 of these 4 small inverters for 2 of these SUN 1000w 240v Grid tie inverters. One has 3 panels from the high roofs. The other connects to the 3 panels on the lower flat roof. They run cooler and quieter and have a bigger reserve (headroom), and seem to track panel voltages better, and have larger quieter fans. The "old" 500 watt ones, will be used in the future for the panels I will fit at the bottom of the garden.
FINAL 4 PANELS.
THIS IS REALLY IT!
I built a frame. I am cheap. So its 63mm (2.5 inch) Exhaust pipe tubing!
Why? I found some very cheap 3 meter lengths of dented stainless steel exhaust tubing!
I built an ADJUSTABLE ANGLE frame. It faces south. It allows me to use it as a summer sun shade, and be turned to around 25 degrees from horizontal in summer, and to about 60 degrees in winter for the low sun.
This is 4x 250 watt panels.
Concrete in a post
At both sides...
60mm Nylon bar drilled and tapped for a "hinge" M10 Stainless bolt. One each end of the 4 meter horizontal bar.
This is that plastic bar fitted. Why use it? Cheap!
Bar fitted. Post concreted, grass replaced. Cables (2x cheap 6mm sq Grey twin and earth cable as used when fitting an electric shower), runs INSIDE this post, and under the grass to my bedroom... At the top of the pole there are 2 Anderson connectors.
Here > Also note the bolt, spacer, and plastic bar, and the extra hole on the outside for an Allen key to tighten the bolt holding the horizontal bar...
Now ready for reinforcement. Triangulation.
This is how the two cable got under the lawn... Ignore the mud, that's where a hollow was filled in when we (I say we! I mean my friend!) dug the post hole.
Panels added. Very wobbly without the triangulation. But I wanted the power to be working.
Triangulation added. This is 2 inch angle iron. 3mm thick. Concreted in. Bolted to the poles with:
The same 65mm U Clamps (cheap exhaust clamps!) as were used on the panel mountings etc.
Dunno what this pic was?
Angle control. 2 bits angle iron, 2 more cheap clamps. Not yet painted silver...
Same thing from front. That bit of bar its bolted to, is a 15mm alloy bar, threaded 8mm both ends on my lathe. It goes through one side of the post and is bolted from the back So one 15mm hole, one 8mm...
Result? Solid, cheap, adjustable. Looks horrible but once I get something growing up the legs it will be invisible!
Actually here's a bigger picture from the other end of the garden. You barely notice it if you squint!
Seeing over 1600 watts generated - even in March 2013 (coldest on record with snow all month) - is not unusual. From 10x 250 Watt panels. I have seen 1700 Watts intermittently. And up to 500 watts on a solid cloud filled day.
This is what I am now using. Top two, are 500 watts each, they are connected to the 4 panels on the frame in the garden. The bottom two are 1000 watt inverters, they are connected to 3 panels each. On the house flat roofs.
Each set of panels is connected in parallel. So shadow, or shade does not affect any other panels. There's no "strings" here.
Total for a 2.5kw system is around £1739 including tax. It MAY not be as efficient as a commercial system. Or since all is in parallel it may be more efficient. We will see.
I used a government site, online calculator, and plugged in a few likely figures and this is the expected result of my 10 panels:
(Actually this is for 9 panels but I now have 10) So far, in May, its almost exactly as predicted by this. At least kWh per day seems like it will top 11 per day. Or 330 per month. Exceeding the estimate.
So it should earn me about 284+ UK Pounds (420 US dollars?) per year. It will cost me 1739 UK pounds to do this with all 10 panels. So it will start to pay for itself after Approx 8.5 years if electricity prices do not rise for 8 years... But they will, so 5 years is much more likely to be the real recovery time. But this is all guesstimation. Either way long after the cost is forgotten (as it mostly is now) the reduced bills will continue! Either way its fun to watch, and in summer at least it is covering 1/2 to 2/3rds of my power usage.
Watch this page for updates!