Solar System Review

[steptoe]

It is NOT a fuseboard. It has no fuses.

Why do you never have any useful constructive input instead of being pedantic all the time,?
The general public understand the term fuseboard more readily than consumer unit,.
You never did answer my previous question as to whether you were an actual electrician, rather than a 5ww installer....

 

[binky]

I agree , no pride in jobs just £££ . It is such a shame. I have had to return to systems years down the road and they have faulted just because no thought has gone into the install. Quick in and out. Most are bad joints and cables not being secured causing rubbing against metal due to wind. They were apparently proper company's. I think it's how the installers are trained ,they don't think just fit. Many use labourers we'll be it they are supervised but as you know they are not.

Favourite failure point MC4 connectors fitted by installers that haven't been done up properly with £3 MC4 spanners. Cost of scaffolding to access fault around £500

 

[Cr4zySmurf]

So the installer has replaced all the damaged panels and added/corrected all the other issues as far as I am aware, although they are still to commission it tomorrow.

Is there a way to check that all of my panels are connected without physically checking? The space underneath the panels is limited and I can't see for sure if they are connected. Can I use the string voltages from the GivEnergy app maybe?

I just want to check that all panels have been connected up because the installer originally tried to reduce the panel count from 14 to 12 due to an inverter requirement, but I checked with inverter supplier and 14 panels was okay due to the panels having a low enough Voc so it was agreed to install all 14 panels.

However I don't trust the installer due to all the issues I've experienced with them and I want to make sure they didn't just add the extra panels without connecting them.

 

[binky]

Panel data sheet will tell you the panel output voltage, multiply that by number of panels to get the expected string voltages. You could also stall the system by switching off the AC, and use VOC for the panels.

 

[Cr4zySmurf]

Panel data sheet will tell you the panel output voltage, multiply that by number of panels to get the expected string voltages. You could also stall the system by switching off the AC, and use VOC for the panels.

Thanks, so if I take the Voc of the panel 37.32V and multiply that by 7 = 261.24V. So I should expect to see approximately 261.24V.

String 1 = 209V / 37.32Voc = 5.60 = 6 Solar Panels?
String 2 = 223V / 37.32Voc = 5.97 = 6 Solar Panels?

Saying that I did get a spike of 4956kW during the day which wouldn't be possible with 12 panels?

 

[Barx]

Bare in mind that reading the voltage on the inverter like this is NOT Voc. 'in circuit' voltage which will always be lower that open cicuit voltage.
Not sure about that particular inverter but some inverters you can turn the AC supply off and the inverter is still live and you will get a voltage a bit closer to Voc.

Is 1 string in the sun and 1 out the sun? temperature tends to affect voltage, panels don't like to be hot. That could explain the different string voltages.

The only real way to get the right number is to open the circuit, but you can only really do this if you are compentent to do so. i.e turn off dc isolator, then either a) open DC isolator and test incoming cables at the terminals or 2) disconnect DC plugs from inverter, connect test leads to then and turn DC iso back on.
DO NOT disconnect the plugs under load without turn isolators off first.

Also note, DC power stings quite a bit and is more dangerous than AC. So, if you decide to faff, please be very careful.

 

[Cr4zySmurf]

Bare in mind that reading the voltage on the inverter like this is NOT Voc. 'in circuit' voltage which will always be lower that open cicuit voltage.
Not sure about that particular inverter but some inverters you can turn the AC supply off and the inverter is still live and you will get a voltage a bit closer to Voc.

Is 1 string in the sun and 1 out the sun? temperature tends to affect voltage, panels don't like to be hot. That could explain the different string voltages.

The only real way to get the right number is to open the circuit, but you can only really do this if you are compentent to do so. i.e turn off dc isolator, then either a) open DC isolator and test incoming cables at the terminals or 2) disconnect DC plugs from inverter, connect test leads to then and turn DC iso back on.
DO NOT disconnect the plugs under load without turn isolators off first.

Also note, DC power stings quite a bit and is more dangerous than AC. So, if you decide to faff, please be very careful.

Thanks for your suggestions.

Both strings are on same roof, one above the other, no shading.

I'm don't want to tinker with it in a way that may affect the warranty, but could turn off the AC supply at the isolator and use the new voltages. Although I am more confident now that all 14 panels are connected and working.

 

[binky]

You wouldn't have got power spike without 14 panels connected

 

[UNG]

Why do you never have any useful constructive input instead of being pedantic all the time,?
The general public understand the term fuseboard more readily than consumer unit,.
You never did answer my previous question as to whether you were an actual electrician, rather than a 5ww installer....

Well said his repetition is getting boring

 

[BorisJ]

Why do you never have any useful constructive input instead of being pedantic all the time,?
The general public understand the term fuseboard more readily than consumer unit,.
You never did answer my previous question as to whether you were an actual electrician, rather than a 5ww installer....

That was constructive. A fuse board is a different animal to a CU.

The general public need educating if what you say is true. Some sparks do as well it seams.

 

[binky]

That was constructive. A fuse board is a different animal to a CU.

The general public need educating if what you say is true. Some sparks do as well it seams.

Have you ever tried educating the public

 

[Cr4zySmurf]

Day 34 and this cowboy company still haven't completed my solar installation ... someone visited to finish commissioning end of last week and realised that they needed to install a communications cable which has taken 3 visits to detect, then realised that they threw out the inverter connectors along with other spares on the previous visit thinking they were rubbish/surplus so now I am waiting for their 4th attempt to complete this installation hopefully at the end of the week. Company complaints department aren't responding to my emails.

I have registered a complaint with MCS for poor workmanship and looking to get compensation through HIES due to the communication issues, financial loss, inconvenience and damage to property.

 

[Bob Smith]

Sorry to hear of all your problems @Cr4zySmurf
I too had minor issues with my installation in 2016. I had 16 panels on 2 string all facing south. A friend of mine about 500yards away has the same installation with the same installer but his panels are 8 facing East and 8 facing West a part of this, same panels, same inverters. We had them installed beginning of January. As expected he generated earlier and later than me and during day time it was about the same. However as spring came I expected my system to start generating more but no. I started to think there was a problem. They connected to my system and found out only one string was connected to the inverter. They came connected it and suddenly I had twice as much power. However, I lost 3 months of Fit. I complained and they gave me the money.

I notice that you have 14 x 410W = 5.7kW which is higher than the max allowed without DNO approval. Do you have a limiter and therefore have a inverter for 4kW or have got the DNO approval for higher power? If so I am interested to learn about your journey for DNO approval.
Thanks and hope your issues are soon sorted

 

[Cr4zySmurf]

I notice that you have 14 x 410W = 5.7kW which is higher than the max allowed without DNO approval. Do you have a limiter and therefore have a inverter for 4kW or have got the DNO approval for higher power? If so I am interested to learn about your journey for DNO approval.
Thanks and hope your issues are soon sorted

I have a 3.6kW inverter, and a PV array power rating of less than 6kW which I believe are the limits, if I had an inverter larger than 3.68kW then I would require DNO.

It means that I will waste some produced electricity on the summer days when conditions are optimal as my inverter will only be able to use 3.6kW with the rest clipped. But in the UK they are minimal compared to the rest of the year.

I chose this so that during the rest of the year when the conditions aren't as optimal then I'll be producing near or at 3.6kW making the most of the system. Also I have the option to upgrade to a 5kW inverter and apply for DNO in future without having to do anything on the roof with the panels.

Note that some inverters do limit the size of the PV array as they are rated for a certain voltage etc. My installer tried to reduce my panels from 14 to 10 because they didn't understand it, but after discussion with the inverter manufacturer they agreed to install the 14. Basically the total Voc of my panels was less than the max input voltage of the inverter. The installer was looking at the inverter max power rating.

Have a look at the below link.
https://energysavingtrust.org.uk/sites/default/files/reports/Solar pv connection to the grid.pdf

 

[binky]

I'm not a fan of clipping outputs. It was fairly normal to size inverters at 80% of array size 10 years ago, but then we were still using wire wound transformers whose efficiency could drop off to as low as 70% when outputs were poor. The transformerless inverters we use now drop to around 94%, so even in winter efficiencies are still high, but you are losing summer / autumn / spring outputs that possibly could be putting a bigger hole in your bills or being used to charge a battery, EV or heat water.

 

[Cr4zySmurf]

I'm not a fan of clipping outputs. It was fairly normal to size inverters at 80% of array size 10 years ago, but then we were still using wire wound transformers whose efficiency could drop off to as low as 70% when outputs were poor. The transformerless inverters we use now drop to around 94%, so even in winter efficiencies are still high, but you are losing summer / autumn / spring outputs that possibly could be putting a bigger hole in your bills or being used to charge a battery, EV or heat water.

I agree, I only found out afterwards that I would be better off having a larger inverter so that I could charge the battery quicker, and use the excess to heat my water with the iBoost. Don't know why the sales didn't mention it, would have been a little more money for a lot more benefit.

Anyway, stuck with this now until the inverter fails, then I'll upgrade to 5kW one.

 

[Bob Smith]

I agree, I only found out afterwards that I would be better off having a larger inverter so that I could charge the battery quicker, and use the excess to heat my water with the iBoost. Don't know why the sales didn't mention it, would have been a little more money for a lot more benefit.

Anyway, stuck with this now until the inverter fails, then I'll upgrade to 5kW one.

In that case you would have needed DNO approval, I assume? Is that not what you wanted to avoid?

 

[Bob Smith]

Earlier in that post, we were talking about temperature in the attic and the temperature of the inverter. Mine is in the attic and here is the temperature profile for today

 

[Cr4zySmurf]

In that case you would have needed DNO approval, I assume? Is that not what you wanted to avoid?

Yes, I wanted to avoid it because of the wait and potential cost of it. At the time I didn't know I could have had a 5kW inverter and limited the supply to grid to avoid a DNO but still have the benefit of 5kW inverter for Battery and Water Heating.

 

[Bob Smith]

Yes, I wanted to avoid it because of the wait and potential cost of it. At the time I didn't know I could have had a 5kW inverter and limited the supply to grid to avoid a DNO but still have the benefit of 5kW inverter for Battery and Water Heating.

That is a very good point. Thank you so much. I will consider this.
The only drawback I see is if you want to also benefit of selling to the grid, you won't be able to maximize the export (after you have taken for yourself what you need, consumption, batteries, water, maybe car etc...)