PV Gap

Nathaniel Said:

What is the difference between crystalline and amorphous solar pv panels from a manufacturer view point??r?

We Answered:

Crystalline comes in an ingot, which you must saw into wafers. Or else you must buy wafers, paying someone else to saw it. That costs more.

Amorphous can be deposited as a film, cheaper to make. And as you know, it's not as efficient or durable as crystalline.

Louis Said:

pv (solar) panels that are installed/ran for free : will they put them up North facing do you wreckon ?

We Answered:

It would only make sense to put up north-facing PV panels if you live in the Southern hemisphere. PV panels' electricity-generating ability drops off dramatically as the angle of sunlight moves away from perpendicular to the surface.

Jimmie Said:

should I buy pV solar panels or get them for free?

We Answered:

If you are offered panels for free then buy them your self as you would have been assessed as being a good investment for the free suppliers. I have bought my own panels after being offered them for free and I got back about £70 in October on my 4Kw system, (sun at a low level and dull most of the time) from my £12,500 investment.

Another thing is if you have them for free you are not in full control and maybe the person buying your house one day wants there own panels on. Don't be rushed into it though because your have plenty of time before the cash back goes down from 41 pence a unit generated down to 36 pence a unit (Kwh) Also the most you are allowed to generate is 4Kw before the cash back goes down from 41 pence per unit.

The VAT on solar PV installation is 5%. The down side is that most installers want about 80% up front although they have to be insured as part of being a qualified MCS installer.

If you choose to buy your own system and get it installed by a person taking the practical part of the MCS qualification then you would save on labour, but you would have to pay VAT at 17.5% (20% Jan 2011). I reckon I would have paid around £16,000 for BP panels with a fully qualified MCS installer. There was a few problems due to inexperience but the installer got there in the end. I paid for scaffold at £235 for two weeks on a bungalow and his fuel to come from Hull and with another helper from Bradford to Hucknall at a cost of £300. I should have found someone local but it was still a good 99 pence worth from an auction site as the total cost including parts and everything with no labour charge was still only £12,500. The feed in tariff is still paid when the installer passed his practical test

If your worried about damage to your roof as I was then it should be ok as the brackets are screwed to the large joists sandwiching the felt so there is no moisture penetration. The cables pass through lead seals called grommets and again water cannot pass through.

I could have had Chinese panels for half the price of my BP ones but did not feel comfortable with the foreign guarantees, especially when the guarantee on the panels lasts for 25 years. That was personal choice though.

I suppose one other thing is that with the panels is to make sure they are on your roof as they are quite expensive and could be a target for thieves if they were ground mounted. Better still make sure your insurer knows they are fitted.

Take a look at my set up at:

http://philippine.synthasite.com/solar-pv.php

Amy Said:

how can i calculate the Kwp, for PV solar panels?

We Answered:

The supplier should tell you.


kWp =
Area * efficiency of the panel AS A FRACTION (so 15% efficient = 0.15)


This is pretty simple because efficiency is calculated for a spectrum of light with 1kW per metre squared intensity. The real equation is kWp = Area in m^2 * assumed intensity of 1 kW m^-2 * efficiency.


You could also calculate it if you know the maximum current out and voltage from P=IV.



If you can't find any info for your panels, you can try looking at panels on the internet and seeing what they give you in kWp/m^2.