Solar PV Panels

thenudeone

ccnp,

Your appliances just use electricity when you switch them on. They don't "know" where it came from.

Transmission losses are nowhere near as much as you suggest, based on my research using Fronius' software, which allows you to select the cable size and it will tell you the losses in percentage.
For a 30m cable length on 2.5mm cables it states cable losses would be 0.45%. For 6mm cable it is only 0.19%
http://www.fronius.com/cps/rde/xchg/fronius_international/hs.xsl/83_8594_ENG_HTML.htm

So - the most you could benefit from would be to eliminate the 0.19% losses.

Cardew

ccnp wrote: »

There is a 15m run of 6mm 12v supply. I have found calculators that suggest reducing this to 3m by moving the inverter will improve the situtation by c. 10%. That is around 1 kwh pd avg (44.8p pd inc export) and I can see a case for doing the move. There would be more power into the house as well.

thanks for any suggestions or references

As stated above the transmission losses will be negligble.

Any loss in a cable has to be dissipated as heat, and at 10% your cable would simply melt!

zeupater

ccnp wrote: »

Apologies if this has been covered but I haven't spotted it on a trawl through the lists

How does my house know to use the PV electricity ? I seem to remember this is based on voltage but my system is usually below the grid voltage when I look.

2nd; transmission loss. I opted to have the inveter in the garage because the roof space used to suffer dramatic hot/cold swings. The PV panels now cover 90% of the space and has vastly reduced this problem. There is a 15m run of 6mm 12v supply. I have found calculators that suggest reducing this to 3m by moving the inverter will improve the situtation by c. 10%. That is around 1 kwh pd avg (44.8p pd inc export) and I can see a case for doing the move. There would be more power into the house as well.

thanks for any suggestions or references

Hi ccnp

As per previous posters, there is little to be gained and a number of disadvantages. My inverter is in the garage & that's the way it's staying. Your installer has compensated for DC resistance losses over a longer run by using 6mm cable, if the inverter was in the loft they would probably have used 4mm.

On 6mm cable as a like-for-like basis, your system would probably be somewhere around 0.25% more efficient with the inverter in the loft, but this needs to be balanced against inverter life & the possibility of temperature derating as my loft still goes above 40C (when the convective clouds allow it) .... it touched 36C a couple of days ago, but we haven't had a cloudless day since early May when I placed a sensor up there.

Derating the inverter by around 10% for around 5 or 6 hours over a year will reduce generation by more than 0.25%, the other way of looking at it is if keeping the inverter cooler or the operating temperature range more stable it lasts a week longer over 10 years the decision will be in profit ...... well that's the way I see it and made my own decision ....

HTH
Z

System

Twelve panels installed 7th September 2011
Earnings so far:
1st quarter to December 2010 = £134.83
2nd quarter to March 2011 = £69.34
3rd Quarter to April 2011 = £213.04
Total £417.21
Now 28.6.11 and on course to earn about another £300.00 through July and August to the First Anniversary, which will make a total of about £700.00. We are having 16 hour days just now and that makes a huge difference.
In addition my electricity bills have been reduced by about 40%. EON (my service provider) happens to have have a comparative consumption chart (nothing to do with solar panels) which give a direct comparison with the previous year's electricity costs.
These are real figures by a consumer and on an outlay of £9500 this means a return of about 7% tax free and index linked. Ok I can't go to the bank and draw the money out, but compare it with buying a new car where you would loose half it's value in three years. It's a no brainer if you can afford the capital outlay.
The inverters are coupled to a computer which can monitor all sorts of historical information too.

liklylad

I have been trying to locate a solar manufacturer in order to install these myself,can I find one no chance there appears to be a situation out there that stops anyone bying and installing the pvc electriciy panel and subsequently having them checked by an electrician

zeupater

liklylad wrote: »

I have been trying to locate a solar manufacturer in order to install these myself,can I find one no chance there appears to be a situation out there that stops anyone bying and installing the pvc electriciy panel and subsequently having them checked by an electrician

Hi

There are loads of distributors out there who will sell to you, but if you install yourself you'll not be able to collect the FiT payment and therefore the DIY route would be a really bad mistake ... research the FiT scheme requirements before making any decision.

HTH
Z

John_Pierpoint

It is a bit like the days when only soliciters were allowed to charge for conveyancing - and we got firms of one or two solicitors and an office full of clerks, doing the actual work, which sold for an inflated price.

Mind you the output from the panels on full power could be dangerous - as we don't use the USA system of each panel having its own inverter - and the inverter/control has to turn off everything when there is a power cut; or the guy up a ladder fixing the broken wire, would get a nasty shock.

mickyduck

poor1 wrote: »

Twelve panels installed 7th September 2011
Earnings so far:
1st quarter to December 2010 = £134.83
2nd quarter to March 2011 = £69.34
3rd Quarter to April 2011 = £213.04
Total £417.21
Now 28.6.11 and on course to earn about another £300.00 through July and August to the First Anniversary, which will make a total of about £700.00. We are having 16 hour days just now and that makes a huge difference.
In addition my electricity bills have been reduced by about 40%. EON (my service provider) happens to have have a comparative consumption chart (nothing to do with solar panels) which give a direct comparison with the previous year's electricity costs.
These are real figures by a consumer and on an outlay of £9500 this means a return of about 7% tax free and index linked. Ok I can't go to the bank and draw the money out, but compare it with buying a new car where you would loose half it's value in three years. It's a no brainer if you can afford the capital outlay.
The inverters are coupled to a computer which can monitor all sorts of historical information too.

Hi What sis the designed output of your system?
TA

AidyB_2

malch wrote: »

what i am tring to get at is that the salesman kept pushing the fact that their system could start working 1/2 an hour earlier in the morning and stop 1/2 hour later in the evening, also in poor light it would be producing, albiet a small amount, whereas the units coming in at 175v-200v may not produce at all. now over a year that could amount to a reasonable amount of kW. this was the reason i went with PV Solar rather than the two other companies who would prise match the same system, but with alternative inverters

Long time out of date, but just worth noting that a lower start-up voltage on an inverter does not mean that the inverter starts earlier in the morning. Actually early morning or late at night the panel voltage is higher as panel voltage is lower with high temperature. It is the current that increases with irradiance

It is sharp sales tactics, nothing more or less.

Sorry

Rosemary_Jane

Hi, may I join in this thread?

I have recently had a PV system fitted (south Kent), on the flat dormer roof of my house - I know this is not ideal, however, it was the only option if I wanted to join in the fun.

I have not considered the payback period as such, because I can't get the money back, so I have compared it to buying an annuity, approximately, as I used the money I got back from an annuity scheme that I was paying into for many years. The company offered me £890 flat rate a year or £16K; so I took the money and bought the PV panels - I hope to beat that in year one!

I got several quotes, and read lots of books and websites. The main options were,

A) £18.5K for a 2.6kWp system, in two rows of 'landscape' panels on a sloping mount system (16 panels)(and planning permission and £600 for a roof-strength survey requiring tearing down the ceilings to check the joists)

£14.1K for a 3.96kWp system, in two rows of 'portrait' panels mounted horizontally (22 panels) (no planning, survey inclusive, free Sunny Beam to play with, no disruption in the house, and a local company which gave me details of 3 installations within 5 miles so that I could speak to the householders about their experiences).

Now I know that horizontally mounted panels will not give me the peak output of an appropriate slope; and my location isn't great, given that the whole house gets no direct sunlight at all in two winter months (cliffs!) but I've been happy with what they've produced so far.

On several days I've noticed power production has been 3.81kW, which is probably the maximum, but production begins quite early in the morning, often over a kW by 7am, and goes on late, til around 9pm, which may offset the disadvantage of not making 3.96kW at noon.

The system was commissioned late on 24 May,so:
7 days of May, highest production 27.69kWh, lowest 10.18kWh; total 113.72kWh

June, 30 days, highest day 28.12kWh, lowest 2.95kWh(!!); total 552.51kWh

What do you think of the system, does it sound hopeful for beating the pension?

Rosemary