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Solar Panel Guide Discussion
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Martyn1981 wrote: »As you've mentioned before, a blunter tool, is simply to use timer devices, or timers on white goods, and set them to switch on when the weather forecast says the sun will come out (yeah right!)
I tried that. I bought a 500W electric radiator, then a 110V transformer, timer and RCD cutout. The timer drops out for 1 minute every hour, which knocks out RCD. So I have to reset the RCD to get heat and it stays on for an hour only, in order to ensure that I'm not importing. Really, it's not worth it.4kWp, Panels: 16 Hyundai HIS250MG, Inverter: SMA Sunny Boy 4000TLLocation: Bedford, Roof: South East facing, 20 degree pitch20kWh Pylontech US5000 batteries, Lux AC inverter,Skoda Enyaq iV80, TADO Central Heating control0 -
Martyn1981 wrote: »Ooh! That's a tricky question. For myself and anyone with a pre - Aug12 tariff it's an easier decision as the export rate is 3.3p, so it's possible to save money, whereas for installs post Aug12 the export is a much more realistic 4.64p, which is awfully close to gas savings. Don't feel sorry for us, the FIT tariff is much higher and reflects the lower export.
I'm trying to think of uses, for such switches. When our house is coldish, but not quite enough to put the heating back on, I try to maintain temp in two rooms using small leccy heaters 400W + 240W, they don't make a lot of difference, but help keep the chill off. For something like that a simple 'intelligent switch' (one that doesn't modulate the power) would work well. But for you the lost export (post metered export if it ever arrives) would negate most of the savings, though my thoughts are that a small amount of heat in a couple of rooms, is possibly better than running the GCH through the house, even with TRV's on all rads. Not sure I can back that up, just a gut feeling.
Another problem, would be for devices like washing machines and dishwashers etc, since once on, you won't really want them to stop when a cloud comes over. Perhaps the switches or some switches also have 'on only' modes, so they wait for generation to reach a critical point, then just stay on - I don't know(?)
Quick question, a few posts back you said that you had a heating only boiler. How is your water heated, is it by another boiler, or via an immersion?
Mart.
The water is heated by our heat only boiler and stored in the hot water tank (3kw immersion heater fitted) which is located in a upstairs airing cupboard. `Her in doors` finds it very handy for drying.
Thanks
SL0 -
Sirlaughalot wrote: »Are there any smart devices like immersun that can divert solar energy produced to specific devices?
Thanks in advance
You posted about devices, take a look at the options here:- http://www.diykyoto.com/uk/aboutus/wattson-solar-plus
I have used many of the Companies range, found them very accurate and reliable, in particular the OptiPlug. Smart meters will [when you get one fitted] inform you of your usage etc. but will not divert to your chosen appliances from your PV. If you need more info, please post on my usual thread 'talking bout my generation'. :rotfl:2.5 kWp PV system, SSW facing, 45 Deg Roof. ABB Inverter, Monitor: 'Wattson'.
Reg. for FIT Nov 2011. "It's not what you generate; it's how you use it that matters". One very clean Vauxhall Diesel Sri, £30.00 Road Tax:
Definition of 'O's = kWh/kWp (kWh = your daily & accurate Generation figure) (kWp = the rated output of your PV Panels).0 -
Evening all,
The first of my local PV installer quotes is in. The salesman suggests 16 perlight mono panels 250 kw 12 on my main roof and 4 placed on a lower roof directly beneath it(above porch/garage in a formation i was unaware of . Cost comes in @ £5999 for a 4KW system.
There is some debate as to the wisdom of trying to string the two configerations into a standard inverter by another PV company. Also the company concerned said there has been some quality issues with this chinese made type of panel.
Any info chaps?
SL0 -
Sirlaughalot wrote: »Evening all,
There is some debate as to the wisdom of trying to string the two configerations into a standard inverter by another PV company. Also the company concerned said there has been some quality issues with this chinese made type of panel.
Any info chaps?
SL
Evening SL. Quite a bit of debate I suspect.
The lower roof presumably has the exact same orientation, but does it have the same pitch? Also does it get shaded by the house, when the main roof is already in sun, perhaps from around 12 noon to 2pm (bit of a rough guess).
If it is shaded or different pitch, then it shouldn't be on the same string as the upper roof, as it will drag down generation. The lower roof will need to be on a separate string, and you'll need a dual MPPT inverter that treats the two strings (12 panels and 4 panels) separately. The problem with that, is that you might struggle to find an inverter that can cope with the relatively low voltage of the 4 panels.
Another option would be micro inverters or power optimisers so each panel operates individually. Would probably add about £500 and might be worth doing ...... but then you're up to the Sunpower quote, which will probably outperform since all panels will be on the main roof.
Have a look at the porch/garage roof tomorrow and see if it is still shaded when the main roof is getting the sun. I get the same (but opposite) effect. My ESE 2.4kWp main roof still has the sun in mid afternoon, but it starts to shade the ESE 1.2kWp lower roof. Once the shade line covers a whole row of cells on the top of the lower panels (IYSWIM) their generation drops abruptly from around 600W to 120W (in good weather).
Mart.
PS Nice price though, so they are coming down fast as you get more quotes. M.Mart. Cardiff. 8.72 kWp PV systems (2.12 SSW 4.6 ESE & 2.0 WNW). 20kWh battery storage. Two A2A units for cleaner heating. Two BEV's for cleaner driving.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
Think very carefully about the height of the sun at Xmas time. You might need to poison next door's tree:eek:
In mid summer a cloudless day for me produces something approaching 25 kWh from a nominally 3.6 kWp system.
In mid winter the cloudless day would be something just over 5kWh - it won't be critical financially but a shadow tracking across the panels at noon could be very frustrating, Winter generation is probably more important for covering the base load of your electricity circuits - all those standby lights and fractional horsepower motors.
[My son bought his first house on a summer's day only to discover that the rear garden was in perma-frost from roughly mid November to mid January as the sun disappeared behind a large retail warehouse about 200 yards away - the upstairs rear bedroom was still bathed in sunshine for most of the day]0 -
Martyn1981 wrote: »Evening SL. Quite a bit of debate I suspect.
The lower roof presumably has the exact same orientation, but does it have the same pitch? Also does it get shaded by the house, when the main roof is already in sun, perhaps from around 12 noon to 2pm (bit of a rough guess).
If it is shaded or different pitch, then it shouldn't be on the same string as the upper roof, as it will drag down generation. The lower roof will need to be on a separate string, and you'll need a dual MPPT inverter that treats the two strings (12 panels and 4 panels) separately. The problem with that, is that you might struggle to find an inverter that can cope with the relatively low voltage of the 4 panels.
Another option would be micro inverters or power optimisers so each panel operates individually. Would probably add about £500 and might be worth doing ...... but then you're up to the Sunpower quote, which will probably outperform since all panels will be on the main roof.
Have a look at the porch/garage roof tomorrow and see if it is still shaded when the main roof is getting the sun. I get the same (but opposite) effect. My ESE 2.4kWp main roof still has the sun in mid afternoon, but it starts to shade the ESE 1.2kWp lower roof. Once the shade line covers a whole row of cells on the top of the lower panels (IYSWIM) their generation drops abruptly from around 600W to 120W (in good weather).
Mart.
PS Nice price though, so they are coming down fast as you get more quotes. M.
Hi Mart,
The porch/garage roof has the same orientation as the main roof and there does n`t seem to be a great deal of difference with regard the pitch maybe 40/45% as opposed to 35% main roof. Thankfully the shading from the main roof is cast onto the verticle supporting wall and falls about 2 foot short of the porch roof.
From what i`ve heard the german made solar world 250 kw mono panels are a leading make and outperforming the advised spec at a price of £5100 from my local supplier (just quoted today for 12 panels) this might be a nore suitable like for like quote against the sun power beasts.
Thanks
SL0 -
Sirlaughalot wrote: »Hi Mart,
The porch/garage roof has the same orientation as the main roof and there does n`t seem to be a great deal of difference with regard the pitch maybe 40/45% as opposed to 35% main roof. Thankfully the shading from the main roof is cast onto the verticle supporting wall and falls about 2 foot short of the porch roof.
From what i`ve heard the german made solar world 250 kw mono panels are a leading make and outperforming the advised spec at a price of £5100 from my local supplier (just quoted today for 12 panels) this might be a nore suitable like for like quote against the sun power beasts.
Thanks
SL
Hi SL, so shading not a worry at the moment, but need to consider the poorer months (GMT months) since the lower the sun gets, the more chance that the lower panels will be shaded, even if the main roof ones aren't. For my lower roof I was quite shocked just how low the sun gets in winter - something you start to appreciate once you've got PV. If it had got any lower, I'd have had to mow the lawn to reduce shading!
Also differing pitch is an issue. Not the biggest issue, but still quite important. The angle of attack between the sun and the panels changes the amount generated. The best angle is 90d with the sun hitting them square on. But the angle will change every day as the sun gets higher, then lower through the year.
If pitches are different, then one set of panels, either the 4 or 12 will not be performing quite as well as the other set. So just like the shading issue will drag the rest down. So you'll need to ensure that they are on different strings. My two ESE roofs are on different inverters.
As mentioned before, one solution is a dual MPPT inverter, but 12 panels and 3kWp may be close to or over the max wattage for each MPPT. And 4 panels may not reach the minimum required voltage for the inverter (and/or the MPPT).
Still not the end of the story as your installer might know of a suitable inverter, you could have two inverters, you could go for something like SolarEdge power optimisers (PO's). So I'd definitely suggest you fully consider this option ........ but, the Sunpower option and price seem to negate the need for the extra hassle, by putting all 4kWp on the main roof.
Hope this doesn't sound like I'm being negative or dismissive of the split system idea. The installer will know a thousand times more than me, I'm simply comparing it to what appears to be a better option you've had ...... so far!
Mart.Mart. Cardiff. 8.72 kWp PV systems (2.12 SSW 4.6 ESE & 2.0 WNW). 20kWh battery storage. Two A2A units for cleaner heating. Two BEV's for cleaner driving.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
BTW SL, since we were talking about monies before, and it looks like you've got a decent chance of a 4kWp system now, I just re-ran the numbers.
This time,
FIT was 3,600 @ 14.9p = £536
Export 1,800 @ 4.64p = £84
Leccy savings £100+ (since it's a bigger system, and you seem to be thinking about ways to utilise)
Total £720
Putting in a cost of £6,500 (as you have a quote), and using a savings rate of 2% net, 3% inflation, gives a breakeven point of year 9, and a year one profit of £265 (£720 - £130 (cost of capital) - £325 (depreciation)).
Mart.Mart. Cardiff. 8.72 kWp PV systems (2.12 SSW 4.6 ESE & 2.0 WNW). 20kWh battery storage. Two A2A units for cleaner heating. Two BEV's for cleaner driving.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
Martyn1981 wrote: »BTW SL, since we were talking about monies before, and it looks like you've got a decent chance of a 4kWp system now, I just re-ran the numbers.
This time,
FIT was 3,600 @ 14.9p = £536
Export 1,800 @ 4.64p = £84
Leccy savings £100+ (since it's a bigger system, and you seem to be thinking about ways to utilise)
Total £720
Putting in a cost of £6,500 (as you have a quote), and using a savings rate of 2% net, 3% inflation, gives a breakeven point of year 9, and a year one profit of £265 (£720 - £130 (cost of capital) - £325 (depreciation)).
Mart.
Thanks for that Mart,
Just had some great news from one firm who quoted earlier. He reckons the first company to quote got it wrong with the roof measurements.
Its now 7.1m x 5.3m which with a bit of tinkering with portrait/landscape variants will allow 16 x 250 KW panels and he reckons with a software update on the inverter the whole system should over perform and pump out 4300/4400 KW! Are there any pitfalls to this software update ie warranty issues or safety concerns
Total cost with a immersun equivalent unit(longer warranty) £6800 if required
SL0
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