Advice on solar panel quotes please?

tunnel

wr_uk wrote: »

Yes thats a flue pipe. SolarEdge with the optimiser right?

Not necessarily, that would depend on how high the flue pipe is and if it can be reduced somewhat. If there's no chance of trimming it down then yes.....solaredge....as you'll be hit with shading nigh on all day(apart from mid-summer when suns directly above). I couldn't say if it would be enough to bring down a whole string but the potential is there.


Can the flue be reduced to the same level as the panels or just above?

wr_uk

I'll look to see what can be done with the flue but i'm guessing not much can be done as the majority of whats poking through is some type of cowel on the top. So would that be the main reason for going with SolarEdge inverter rather that the other or is it just a superior to the others. The guy from CTS said that the inverter is where you should be thinking of making you biggest investment as its that what doing the majority of the work.

He also said the having panels the generate similar to my energy consumption should be the way to go for best ROI rather that sticking as many panels as possible on both sides of the roof as it would take far longer to recoup my investment with at the rate it is today for sending back to the grid. he said that was i viable solution back when the rate was really good but as its dropped the pendulum has swung the other way.

So im guessing the prices are pretty good of whats been quoted? They are certainly better than the first few quotes I had.

Martyn1981

I'm a fan of going big, especially on an E/W install. Costs go up, but not proportionately, as a lot of costs are fixed.

However, in your case, the generation drop off will be quite high as SE will do much better than NW, and a 40d roof pitch will really hurt the NW.

Using PVGIS (based on my location) for 1kWp I get:
Orientation, roof pitch, annual kWhs
W 30d 786
W 40d 757
NW 30d 631
NW 40d 569
and
SE 40d 915

So the combination of being further off-south and steeper, probably damages the argument. But the final nail in the coffin, is the fact that the quotes are suggesting ~4kWp on the SE roof, which is a perfectly good system.

In your case, and admittedly without checking too carefully, I'd suggest you go for a simpler single roof install.

Regarding the flue, the face of the panels will be about 150mm above the roof surface (brackets + rails + panel depth), so if the flue isn't much more you should be ok.

Is the flue from a boiler or a soil pipe? If it's a soil pipe and you have access, you could stop it inside the roof and simply add an air admittance valve to allow air in (not out). Soil pipe vents aren't to let gases out, they are to allow air in, to prevent a syphoning effect that could suck all the water out of the toilet, which would then allow smells to enter the house.

wr_uk

Its a flue pipe, but I completely forgot to take into account that the panels will be raised off the tiles. so shouldnt be too bad. So im just wondering in I need an optimiser

Martyn1981

wr_uk wrote: »

Its a flue pipe, but I completely forgot to take into account that the panels will be raised off the tiles. so shouldnt be too bad. So im just wondering in I need an optimiser

So, are you happy that it's pretty much shade free? Now's a good time to have a look (when the sun's good) as the lower angle increases the amount of shade, say from trees, buildings etc. Take a look at the roof through the day (again on sunny days). Also bear in mind that generation early on and late are much lower, so a bit of shade at those times (and this time of year) is no biggie.

If it's ok for most of the day now, then probably no need to worry for the better parts of the year.

I like SolarEdge, it works well, but it will cost a bit more, and there will be extra kit on the roof (1 PO per panel) that will require access if there's a fault, so you might be better off with an ordinary string inverter.

tunnel

You need to check the shading as per Marts post, if the flue doesn't extend too far above the proposed panels you may well be ok with a simple string inverter system.
There is still the issue of the chimney. Where it's positioned may well cause shade late afternoon during summer months, even though your generation will be on its way down it could potentially make a difference. You could opt for a dual MPPT inverter(2 strings) and position one string to the left(the 2 columns of 4) and one around where the chimney/flue area.
I do believe shading will be minimal(from your drawing) but from experience it's better to be prepared.
My personal choice would be D(bigger the better) and not have to worry about the shading. Only you can make that call after you've checked your roof several times per day to check how you'd be affected with shading.
One things for certain, the prices are much better than your first quotes.

wr_uk

ill check shading tomorrow if the sun is out.

marcelli

...except this quote did not seem to include the battery(ies) which i think the others did. The batteries are a new departure for we consumers, possibly because the FIT has been drastically reduced in the past couple of years. They store the electricity for your use later (as you mentioned) which is a great benefit. I spoke to someone about the batteries and the figure quoted was about £4k.
I was told that if the panels do not generate enough to earn you £500 p.a. then they are not worth the outlay. I am not sure how that holds now with the option of batteries, but given that they seem to be quite a price to buy, either outright or via a loan, it seems to me that if you can afford them then it's worth it, which might sound daft but an outright purchase from a healthy bank balance does at least mean that anything you generate or use is a bonus. You certainly have to make the hay while the sun is shining.

wr_uk

Had a look this morning at the flue im estimating the height poking out is around 50mm so it is quite high. Unfortunately theres no sun so Im unable to see what the cast shadow is like.

Was looking through the figures last night and I'm still at a stage where im 50-50 if its worth while investment....lol the more I read the more unsure I become. What exactly happens with our elec bill? Im I correct in thinking, I immediately get a 50% reduction? Do I get paid 50% of what on the electric that I generate? The excess that not used goes back to the grid for a small return?

tunnel

No your bill doesn't reduce by 50%.
Once you start generating your bills will reduce by the amount of self consumed generation. There's lots of different ways people try to consume their own generation, one is a diverter that sends spare generation to the hot water tank(do you have an immersion?), others (using diverters) send spare generation to heaters, whether they're oil filled or indeed ASHP's(air source heat pumps, aircon units that do heating and cooling)

You'll also find that you'll change your habits and become more aware of your energy usage.
I changed my white goods, tv and fridge freezer(only when they broke though) and have reduced my consumption from 8500kWh to around 3200kWh a year,,,,,with a stay at home wife and 2 little kids(no mean feat let me tell you)


You get paid for everything you generate whether you use it or not, on top of that you then get paid another 50% "deemed" export. This means if you can turn your usage around and only export 25% you'll still get paid the 50(hence the use of diverters).
Don't for one minute think that overnight you'll start using ALL your generation, on dark winter days its easy but in the summer months when generation is high it becomes somewhat harder.