Solar Panel Guide Discussion

-MRS_T-

sly_dog_jonah wrote: »

That site uses South as azimuth, so you can use this table and subtract 180deg to get a True South based azimuth angle.

Martyn1981 wrote: »

Hiya Mrs T. Azimuth, is basically point of interest, so for PV it's the sun, and for the northern hemisphere the sun is to the south. Hence why south is zero (the starting point). So from there, the 360 degrees of the compass still apply. Before south 0 to -180, and after south 0 to +180 degrees.

East is -90
West +90
NE -135
NW +135

and so on.

Mart.

Fruit_and_Nut_Case wrote: »

East = -90
West = 90
North East = -135
North West = 135
etc = dunno

Edit: beaten to it!

Thank you all, I am not so good with this kind of thing and I am trying to understand it all better so like to do some reading.

Martyn1981

-MRS_T- wrote: »

Thank you all, I am not so good with this kind of thing and I am trying to understand it all better so like to do some reading.

Hello again, there's a short 'bit' on using PVGIS on this thread, section 5.

https://forums.moneysavingexpert.com/discussion/3872445

Info is only basic, so you may have already gone further. Give us a shout if you need more help.

Mart.

John_Pierpoint

In case you missed it here is the "Which?" take on pressure selling and the requirement for a real surveyor as well as a salesman.

http://www.youtube.com/watch?v=sf0SobJ8TXY

Fruit_and_Nut_Case

John_Pierpoint wrote: »

In case you missed it here is the "Which?" take on pressure selling and the requirement for a real surveyor as well as a salesman.

http://www.youtube.com/watch?v=sf0SobJ8TXY

I lost respect for Which? years ago when they dumbed-down the magazine. However I started watching this clip but gave up when I saw their slipshod attempts at sub-titling. British Gasoline (for British Gas) and Freedom Tariff (for Feed-in-Tariff) are memorable.

charlieheard

Had a 4kwp system installed last November after a bit of hassle with proposed price reduction. Roof is 30 degrees and faces SSW. Highest production so far is 24kwh at the end of March, but much less during April

The longer days won't have as big an effect as it might seem, as the flat roof can only receive sunlight from a 180 degree angle, where as the sun moves through almost 270 degrees mid-summer. What will change is the angle the sun hits the roof, which should improve performance. However, the panels work best when they are cold, so a baking hot day in mid-summer might produce less power than a cold, bright day in April (I wish!)

At the moment, one of the pipes supplying hot water to our tank is blocked. While we're waiting to get it re-piped, we're using the immersion heater during the day as a load for the panels. As we don't have an export meter, our export is deemed to be 50% of production, so the power to heat the water is essentially free

We have an Efergy energy meter giving power readings every 6 seconds, but have discovered that it cannot tell the direction the power is flowing. A 500w load and 3kw PV generation gives a reading of 2.5kw, but it assumes we're using that, so the figures are now all wrong!

Has anyone yet had to change energy supplier with Solar PV? Anyone had any problems? Just wondering how they handle the export side of things in the transfer...

grahamc2003

charlieheard wrote: »

Had a 4kwp system installed last November after a bit of hassle with proposed price reduction. Roof is 30 degrees and faces SSW. Highest production so far is 24kwh at the end of March, but much less during April

The longer days won't have as big an effect as it might seem, as the flat roof can only receive sunlight from a 180 degree angle, where as the sun moves through almost 270 degrees mid-summer. What will change is the angle the sun hits the roof, which should improve performance. However, the panels work best when they are cold, so a baking hot day in mid-summer might produce less power than a cold, bright day in April (I wish!)

At the moment, one of the pipes supplying hot water to our tank is blocked. While we're waiting to get it re-piped, we're using the immersion heater during the day as a load for the panels. As we don't have an export meter, our export is deemed to be 50% of production, so the power to heat the water is essentially free

We have an Efergy energy meter giving power readings every 6 seconds, but have discovered that it cannot tell the direction the power is flowing. A 500w load and 3kw PV generation gives a reading of 2.5kw, but it assumes we're using that, so the figures are now all wrong!

Has anyone yet had to change energy supplier with Solar PV? Anyone had any problems? Just wondering how they handle the export side of things in the transfer...

Sorry to pop your bubble, but your water heating isn't free! If you're pulling 3kW for your immersion, and only generating 200W at the time (during the overcast days we've been having), then you're paying for (at least) 2.8kW at that time.

Your supply and fit are two separate accounts, so you can switch one or the other independently as you see fit.

Dave_Fowler

charlieheard wrote: »

....

We have an Efergy energy meter giving power readings every 6 seconds, but have discovered that it cannot tell the direction the power is flowing. A 500w load and 3kw PV generation gives a reading of 2.5kw, but it assumes we're using that, so the figures are now all wrong!

....
.

You may find information on this thread is helpful. https://forums.moneysavingexpert.com/discussion/3921935

Be cautious about turning on an immersion heater or other load to use up the excess energy from the panels. As soon as you start to use more than you are generating you will be importing electricity at around 11p per kWh rather than 'saving' the the deemed fits for the exported energy.

Dave F

davidanddeirdre

grahamc2003 wrote: »

Sorry to pop your bubble, but your water heating isn't free! If you're pulling 3kW for your immersion, and only generating 200W at the time (during the overcast days we've been having), then you're paying for (at least) 2.8kW at that time.

Your supply and fit are two separate accounts, so you can switch one or the other independently as you see fit.

This is an interesting point. One can be a bit smart- for instance, the most we can continuously generate on our nominal 1.75kW system is probably about 1.7 (noted as a steady reading around 09.30 30th March, which is probably best steady reading observed in a year of use- we face SE 40deg slope and it was brightly sunny but cool and breezy, from the SE). So, if at that point I want to boil a kettle of water, it costs nothing but a bit more time to use the travel kettle (900W) but a few pence to boil the standard kettle (3kW). I don't know if one could fit a smaller capacity immersion heater, say 1.5kW, but it could certainly pay if you could!

Cardew

davidanddeirdre wrote: »

This is an interesting point. One can be a bit smart- for instance, the most we can continuously generate on our nominal 1.75kW system is probably about 1.7 (noted as a steady reading around 09.30 30th March, which is probably best steady reading observed in a year of use- we face SE 40deg slope and it was brightly sunny but cool and breezy, from the SE). So, if at that point I want to boil a kettle of water, it costs nothing but a bit more time to use the travel kettle (900W) but a few pence to boil the standard kettle (3kW). I don't know if one could fit a smaller capacity immersion heater, say 1.5kW, but it could certainly pay if you could!

That has been discussed quite a bit in the various threads.

If you have gas CH you are of course only saving at the rate you pay for gas - say 4p/kWh. Oil around 6p/kWh or economy 7 at around 5p/kW - surely few people heat their hot water with daytime electricity?

If you managed to save 1kWh every day of the year, with gas you are talking about saving £15 a year, 2kWh £30 etc. How much to wire and fit a second immersion heater?

Even with a 1.5kWh immersion heater if your PV output drops and you don't notice you can end up out of pocket.

More promising is the device discussed in this forum that will automatically connect/disconnect depending on output.

EricMears

Cardew wrote: »

etc. How much to wire and fit a second immersion heater?

Funnily enough, I've just spent the afternoon doing that.

Well, not exactly that. My immersion heater is (I think) a 3Kw job and I've just rewired it through a 110v 'site transformer' which should turn it into a 750w (or thereabouts) version. I shall also include a 'shunt lead' that will bypass the transformer so that I've still got the 3Kw option on very sunny days.

Costs.

Transformer - £16.01 on eBay
male & female (F required for shunt cable) 110v connectors - £4.87 from Screwfix

everything else I had 'in stock' but a 13A socket, a junction box, a couple of metres of 16A cable and a 13A plug shouldn't cost anyone else much more than another tenner.

I reckon that on most days between now & October I should be able to run the 750w heater for several hours. Perhaps 3Kwh per average day or around 450 Kwh from now till Oct.

£45 if I count that at daytime electricity rates; probably around half that if you calculate the amount of oil I'm not going to burn. Could be a one year payback for me; perhaps 3 years if you're buying all the kit and replacing gas heating.