So now I have a solar PV system how do I make the most of it???

chris.blanchett

zeupater wrote: »

Hi

Welcome to the forum :think:

Although some of the above is generally correct (contextually very little actually), it's possible that you need to do a little more research ......

HTH
Z

Some? Very little? contextually? Can you please try to be more specific.
I am an accredited PV installer and what I said above is FACTUALLY correct, but I understand your need to put the newbie in his place with a little dose of condescension.

John_Pierpoint

The message seems to be "If something partially shades your panels - then cut it down". Though some people could have a shadow, such as that of a chimney, that cannot be removed.

Having read the guidance for local authorities and the risks of roofs built from 1830 - 1970 being at risk of overloading.
&
This warning of hot spots if the panels are not generating uniformly.

Do we have more potential pitfalls to discuss?

Never mind the effect of shadows, what about the invisible falling off of output from one of the panels in the series? Will this increase the "stress" on the rest of them?
Should we be installing the system with each panel having its own inverter?
Just how difficult and expensive is it to replace individual inverters up on the roof?

John_Pierpoint

teachergirl wrote: »

Essex does have some advantages;)

Lower rainfall than Rome !

Interesting NOx smog drifting out of London, makes for magnificent sunsets though.

anselld

chris.blanchett wrote: »

Some? Very little? contextually? Can you please try to be more specific.
I am an accredited PV installer and what I said above is FACTUALLY correct, but I understand your need to put the newbie in his place with a little dose of condescension.

Well you have raised two points which, whilst factually correct, do not apply to the vast majority of domestic PV installations which
(a) have bypass diodes fitted in the panels by the manufacturer
(b) are grid-connected without any site storage

We don't want everyone going off worrying that their arrays are going to fail because of hotspots.

teachergirl

John_Pierpoint wrote: »

Lower rainfall than Rome !

Interesting NOx smog drifting out of London, makes for magnificent sunsets though.

Tell me about it. Being a gardener I spend alot of time in my stilletos watering.;)

teachergirl

18kWh produced today so far. Weather forecast for the next two days, dry and Sunny and 18 degrees.:D

lanstrom

teachergirl wrote: »

18kWh produced today so far. Weather forecast for the next two days, dry and Sunny and 18 degrees.:D

I thought I had done well with my 15.38 kWh ;-)

teachergirl

where are you lanstrom? I think I got just over 19kWh from my 3.96kWp system. I do better in the morning than the afternoon due to my orientation.
I have to say I didn't expect to be doing anything like as well for nearly the end of October:D

lanstrom

I am just north of Birmingham. My system is 3.84 kWh on a 22 deg incline south facing roof. No shade.

zeupater

chris.blanchett wrote: »

Some? Very little? contextually? Can you please try to be more specific.
I am an accredited PV installer and what I said above is FACTUALLY correct, but I understand your need to put the newbie in his place with a little dose of condescension.

Hi

Nothing to do with being a newbie whatsoever, however I still believe that fact & context are being mixed a little .... I'll be happy to comply with your request to be more specific, so let's consider the original post .....

chris.blanchett wrote: »

It is worth mentioning that if you live in an area that doesn't enjoy nice long sunny days (ie. the north) your PV system will become a load if it isn't generating electricity. Your installation team should have made note of your location and fitted bypass diodes that force shaded areas of your PV array to maintain the flow of current through the shaded cells and keep it in equilibrium with the unshaded part of the array. Without bypass diodes your array will start to develop 'hotspots' which, over time, will lead to a failure of that module, and thus the entire array, until the faulty panel is replaced.
If you have on site battery storage you will also need to ensure blocking diodes are installed which prevent a reverse flow of current from the batteries to the PV array at night when the PV array isn't generating electricity. You don't want your batteries discharging themselves completely each night as that would completely negate the point of installing them.

Firstly .... "It is worth mentioning that if you live in an area that doesn't enjoy nice long sunny days (ie. the north) your PV system will become a load if it isn't generating electricity." .... Okay, so what's the difference in total insolation between the north and south, well about 20% is in the right ball park, so that's not quite as much as would be implied in the post, also, whether in the north or south, when not generating the system will perform exactly the same. Generating hours in the south will be longer in the winter and shorter in the summer, therefore the difference would really only be related to relative irradiation intensity and average cloud cover, therefore the hours where a system would not be generating enough to cover their own standby load, which in context is around 0.5W in nighttime standby mode, so hardly something which most would consider to be a 'load' and probably constitute an almost negligable difference between north & south over a year .

Let's now consider "Your installation team should have made note of your location and fitted bypass diodes that force shaded areas of your PV array to maintain the flow of current through the shaded cells and keep it in equilibrium with the unshaded part of the array." ... The installation team should have made note of location ?, or should that read surrounding environment (ie shading, orientation etc), anyway, as others have also stated, bypass diodes are already incorporated into the circuitry of most panels which are currently available on the market anyway and what the diodes actually do is not what has been described ... they effectively stop the shaded part of the panel, which will produce a lower voltage, from acting as a parasitic load on the unshaded areas of the panel by bypassing the group of cells in shade, therefore there is no load on those bypassed cells at all, therefore no flow to be maintained and no equilibrium with other parts of the panel.

Regarding "Without bypass diodes your array will start to develop 'hotspots' which, over time, will lead to a failure of that module, and thus the entire array, until the faulty panel is replaced." ... I'll take it that what was meant was that groups of cells within a panel which are in shade become a parasitic load on the cells which are not in shade which generates heat in the shaded cells which can cause eventual failure, or under very rare conditions a fire ... but that, and improved efficiency, is exactly why most manufacturers fit the diodes anyway.

Now for the battery storage, yes, if you have a simple charging panel (without an inbuilt blocking diode) linked to a battery, or bank of batteries, that would be the case, however, if you have a number of panels and batteries in an 'off grid' installation you will probably have a charge controller, which negates the need for a blocking diode anyway. You would also have the option of charging batteries in a grid tied environment where the charging would be controlled by some form of generation sensing, a very crude example is available as standard on the SB4000TL inverter, but additional panel circuit diodes are not required in this example either.

I do hope that this post has been specific enough to help an accredited pv installer follow the reasoning and the context for the original post and understand that it was in no way condesending, or meant to be condesending, so again .... welcome to the forum.

HTH
Z