quoted SAP figure

malch

i have just recieved a letter from my SOLAR PV, supplier/installer stating that their SAP estimation has been adjusted down from 2410.56 to 1261.44 almost exactly HALF their original estimate, given to me on 24th January 2011. how can this be?
the letter looks like it is a standard template with the date, name and SAP figures added by hand with no signiture added.
The original amount i was told to expext in FITs and generation was £1500.
the original system description and SAP Calculation was

number of panels 12

Panel output 180 Watts

Peak System Output (KW) 2.16

Solar Imput Factor 1200

KWh/Year 2592

Orientation Factor 93%

Shading Factor 1

SAP Calculation 2410

can anyone tell me what the new figure will mean to us?
to add insult to injury they never put a stamp on the envelope so cost me £1.36 to recieve it. ( 36p postage £1 handling fee )

thenudeone

2592kwh seems a bit high for a 2.16kW system (unless you are due south and in Cornwall)

However, accepting 2592kwh pa, you can calculate the INCOME yourself by multiplying the generation by the current FIT rate (43.3p) and adding HALF of the generation at the export rate (3.1p). The saving on the electricity bill will need to be estimated separately.
Don't forget the FIT will probably drop to 21p in April 2012.

You'll probably have to ask them what factors they have changed in the calculations.

Why not try on of the many websites which estimate the output for you, just to get a rough idea of what to expect and what factors influence the output? Many of the inverter manufacturers also provide free software to estimate output and allow a lot more variables.

malch

Hi thenudeone
i have had this system up and running since March 2011 my FITs will not be affected in April ( well not as things stand at the moment) what i was trying to establish was the difference i could expect from SOLAR PV UK original estimate and their revised estimate. how could they get it so wrong? a genuine mistake? how many other customers have had the same letter?

Martyn1981

malch wrote: »

Hi thenudeone
i have had this system up and running since March 2011 my FITs will not be affected in April ( well not as things stand at the moment) what i was trying to establish was the difference i could expect from SOLAR PV UK original estimate and their revised estimate. how could they get it so wrong? a genuine mistake? how many other customers have had the same letter?

Top of the head estimate would be about 2,000kWh's, as you appear to have a good location and orientation.

At approximately 50p per kWh (FITs, savings and export combined) that works out at about £1k income and savings per year.

2592, would be nearer to £1,300 even with 50% consumption, so those sales numbers may be worth challenging.

You probably have some recourse through REA, as all estimates should be based on government stipulated data, preventing over estimates.

If you have some monthly TGM readings, then I'd pop your details into this site, and see how they compare:-

http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php

The default 14% system losses is probably too high, 10% maybe closer to the mark.

Give me a shout if you want more info, too much to post here in one go.

Mart.

PS - sudden thought, presumably you have the 180's for a better fit, if you transpose a more common size 225 panel into those calcs (2.7kWp system) you'd probably be nearer the companies original estimate. So could be a typo, and there responsibility. M.

reeac

Your circumstances are very similar to ours. We had a 12 panel, 2.2kWp system installed in early Feb. 2011 - no shadowing and almost perfect orientation. The installer's estimate was 1850 kWh per annum but we've got to nearly 2230kWh so far and I'd expect 2250 kWh for the full year so I guess that it's been an unusually sunny year. Your location in Poole should be at least as good as ours in coastal Suffolk so I'd expect you, also to generate about 2200kWh. You must have a PV meter - what does it read? Regarding the finances it's simplest just to say that you'll earn overall [via PV cheques and savings on National Grid supply] 53p./kWh generated i.e. forget the agonising over whether you use the washing machine when the sun's shining etc. Your initial estimate looks far too high. We've received three cheques totalling £989 so far and our mains meter reading is less than I'd expect it to be [if we had no PV] by about 1100kWh but it will take time to establish that saving more accurately.

malch

system was installed in Feb and my meter readings from installation is now 2251.unfortunatly we lost the first 163 through not having the correct paper work. but yes reeac we do appear to be on a par with you. just awaitin our third cheque wich will put us around the £900 mark, so i do see us making the £1000 in the first year plus what ever we save on using electicity during the sunny periods.
incidently i have tried to phone my PV supplier, went through the automated system got it ringing then said there was no-one available to speak at the moment, please leave a message after the tone, and then, DOOOOOOOOOOOOOOOOOOOO! dead as a Dodo.

Martyn1981

Looks like your going to be close to the original estimated generation, so that's good news.

But yes total income will be a little less than specified, maybe around the £1,200 mark (if those lost units were included). Not bad though, and another 24 years to go!

If that original £1,500 is documented and not caveated, you may still have some recourse through the REA scheme. Maybe have a read through the documentation.

Mart.

SouthernAir

Was the figure that they quoted a SAP figure? If it was then they are seriously guilty of misselling. You should speak to the REAL and tell them.

Assuming your property is south facing, the SAP figure should have been 1,801kWh. So where the figures of 2,592kWh and 2,410kWh come from is anyones guess.

They have quoted you a full 50% more than what the SAP figure should have been.

Your system may well have done well this year (most systems have), but it has been an above average year for sunlight. Next year may be different.

Johnandabby

SouthernAir wrote: »

Was the figure that they quoted a SAP figure? If it was then they are seriously guilty of misselling. You should speak to the REAL and tell them.

Assuming your property is south facing, the SAP figure should have been 1,801kWh. So where the figures of 2,592kWh and 2,410kWh come from is anyones guess.

They have quoted you a full 50% more than what the SAP figure should have been.

Your system may well have done well this year (most systems have), but it has been an above average year for sunlight. Next year may be different.

Yes, they can't use SAP to calculate it, as the SAP calculation uses an 'average' UK location and wouldn't take into account solar intensity at the specific location. As advised above, speak to REAL - could at least stop them misselling to others in the future

jimjames

Johnandabby wrote: »

Yes, they can't use SAP to calculate it, as the SAP calculation uses an 'average' UK location and wouldn't take into account solar intensity at the specific location. As advised above, speak to REAL - could at least stop them misselling to others in the future

Out of all the companies we spoke to for quotes on our installation the one with the most dubious sales tactics and annual output calculations was PV Solar UK. They claimed they didn't need to use SAP calculations as they'd been given permission by REAL so their numbers were significantly higher than any other supplier. As a consquence their payback was far better than anyone else despite having higher prices.

Apart from the dodgy sales tactic of spending 10 mins tapping away on a calculator to give "the best price if we sign now" despite having laptop there, the other element that immediately sparked alarm bells with their payback was them using an annual inflation figure of 15% for electricity prices.

Yes it may have been 15% last year but 15% pa compounded over 25 years that would mean 80% of your salary was paying for electric by then! Obviously giving massive numbers made their investment payback look very good if it hadn't actually been total fantasy.