Solar Panel Guide Discussion

John_Pierpoint

Yes but depending on your usage of hot water, the size of your tank, the size of your inverter and the orientation and slope of your roof; given that nobody seems to be installing export meters, then for much of the summer it is possible to heat your hot water for free or at least a third of the normal electricity price? It helps to be working at home between 11 & 3 though.

zeupater

John_Pierpoint wrote: »

Yes but depending on your usage of hot water, the size of your tank, the size of your inverter and the orientation and slope of your roof; given that nobody seems to be installing export meters, then for much of the summer it is possible to heat your hot water for free or at least a third of the normal electricity price? It helps to be working at home between 11 & 3 though.

Hi John

That's where the correct specification of the type and size of HW cylinder needs to be considered ... and this is true whether the heat is provided by thermal panels or excess pv generation.

The sun doesn't shine every day and therefore the HW tank needs to provide enough of a buffer to cover average usage for a few days of low solar energy provision if there is to be any real advantage afforded by modifications to the HW heating arrangements.

What needs to be considered is that there is definately a difference between a system modification made in order to maximise self-consumption of generated electricity and one designed to provide the majority of the annual HW requirements ....

HTH
Z

digitaltoast

We've often debated the merits on this thread of solar PV vs the subsidy given and our usage patterns. I just found something I've been looking for for ages, http://gridwatch.templar.co.uk/, where you can also download 108070 rows of data going back over a year in a 5 minute resolution with the columns:

timestamp	demand	frequency	coal	nuclear	ccgt	ocgt	french_ict	irish_ict	dutch_ict	pumped	hydro	wind	oil

I'm becoming reasonably familiar with Google Graphs and Fusiontables, and what I'd love is if anyone would give me access or a link to their historical PV generation data. I'd like to overlay the graph of PV generated and time, with UK demand. Should be quite interesting, yes?

EDIT: OK, raw data imported into public fusiontable: https://www.google.com/fusiontables/DataSource?docid=13Cq3fZuVAiAF7U2CXkUYC69ztZz1gqR7chIs15c

Open table, select "Experiment", and "Zoomable Line Graph", then you can plot anything you like, for example:
Demand: https://www.google.com/fusiontables/DataSource?snapid=S533432hQon
Frequency: https://www.google.com/fusiontables/DataSource?snapid=S533433GN6Q

Add compare, for example, here you can see how demand spiked as we sold to the French through the interconnect when they had the little problems earlier this year: https://www.google.com/fusiontables/DataSource?snapid=S5334343yha - you can of course zoom right in to a 5 minute window or out to over a year.

What's this got to do with solar? Well, imagine if we could merge the publicly available weather data, with this grid data AND the solar generation data...
All that's missing is that last part....

birdgarden

Steell wrote: »

Think Green Earth are no longer advertising Solar Panels on their website and I've had a refund via my credit card company at last

you are lucky i cannot contact them at all have been onto cheshire trading standards and have sent aletter telling them of breach of contract as advised by ts not heard anything yet, contacted the company who install the panels and they haven't had anything to do with them since jan 2012, i was told by therm that they are still trading from their address in marple cheshire. we paid by debit card
thanks

sly_dog_jonah

Since having our PV installed (roof mount) we've noticed a considerable drop in TV signal reception via our loft-mounted aerial. It wasn't an overnight change, but over especially now in summer (different atmospheric conditions?) we've found two digital multiplexes are unwatchable. Unfortunately our local transmitter is due South, so our aerial currently points right through the PV. Most panels include a foil-based backing, so they are a fairly effective reflector/attenuator of TV signals. For further reading, see http://www.aerialsandtv.com/loftaerials.html

We've currently got an aerial installer up in the loft trying to reposition it for better signal, but its quite likely we'll need to reposition it on one of the chimney stacks (with shading minimised as far as possible).

EDIT: Fortunately he was able to reposition the aerial at one end of the loft and avoid the attenuation, so we won't be need to risk any shading on the roof. One happy household with the return of CBeebies and the HD multiplex!

ronlizpatsimon

I've had my Panels for 9 months. I have found that with a clear sky at noon (GMT) I get no more generation now (June 18th) than I did in early September or Early April (3.7 kw). The Total per day on those rare "clear all day" days is about the same too (20 kwh).
I suppose the reason could be that in early Apl. and Sep. The sun is shining directly onto my 45 degree angled panels. Currently the sun (at noon GMT) is at 61 Deg. Another related thing I have noticed is that despite a very early sunrise now; very little generation occurs until the sun shines directly onto my panels (about 7 am GMT). The same occurs in the evening despite the late sunset, I get very little generation after 7 pm (GMT).
Any comments anyone?

sly_dog_jonah

ronlizpatsimon wrote: »

I've had my Panels for 9 months. I have found that with a clear sky at noon (GMT) I get no more generation now (June 18th) than I did in early September or Early April (3.7 kw). The Total per day on those rare "clear all day" days is about the same too (20 kwh).
I suppose the reason could be that in early Apl. and Sep. The sun is shining directly onto my 45 degree angled panels. Currently the sun (at noon GMT) is at 61 Deg. Another related thing I have noticed is that despite a very early sunrise now; very little generation occurs until the sun shines directly onto my panels (about 7 am GMT). The same occurs in the evening despite the late sunset, I get very little generation after 7 pm (GMT).
Any comments anyone?

Based on the data sheet of your inverter, the maximum AC power output is 3.5kW. I guess the 3.7kW is the inverter's DC reading? Either way, the maximum instanteous power will probably be achievable on most days of the year on a good day. Remember that cooler days are better than hot days for solar panel efficiencies, so on sunny summer days your system's output may be constrained.

Your panels will only create appreciable output when the panels are in direct sunlight, so that explains why your observed summertime outputs in early morning and evening are lower than X hours after sunrise at other times of the year. In winter, your panels probably get direct sunlight sooner after sunrise than at this time of the year.

KevinG

ronlizpatsimon wrote: »

I've had my Panels for 9 months. I have found that with a clear sky at noon (GMT) I get no more generation now (June 18th) than I did in early September or Early April (3.7 kw).

My experience is similar to yours - I've had the panels for just over a year and my best day ever remains 30th April 2012, followed by several days in late May. I haven't had anything in June, July or August to touch it. Even the 6th April beat anything last summer. Maybe it's the panel angle (37 deg), maybe it's the temperature, but then I don't think I've yet had a solid dawn to dusk day of sunshine in the peak of summer to compare it with.

orrery

ronlizpatsimon wrote: »

I've had my Panels for 9 months. I have found that with a clear sky at noon (GMT) I get no more generation now (June 18th) than I did in early September or Early April (3.7 kw).

I'd guess that this is the 'average maximum' that your system can deliver - i.e. the maximum output (4kW?) de-rated by the temperature rise caused by self-heating. It is probably true to say that this value is lower in high summer than it is in spring/autumn because the ambient temperature is higher.

shena

:(I am trying to chase them up they owe me £379.
Keep your fingers crossed for me.