Solar Panels UK - is it worth it?

[yessuz]

question, again.

Got quote:
- 10 solar panels on east facing roof, 10 on the west // (total 20). system size 8.2 kw
- Inverter: Lux Power 3.6 kw (LXP Hybrid)
- Battery: 9.6 kwh (3x LV--L3.2-1P
-------
13.5k

vs
- 6.56 kw system (16 pannels, 8 east 8 west)
- same inverter
- same battery
-----
12.5 k

I think the 20 pannel is better..
however I am worried about inverter size... 3.6 kw is more or less 1 kettle and a bit. if I have oven or washing - the pull from system exceeds the capacity. or do I read this wrong?

we are working from home and wife disagrees on washing machine/dryer running over night...

 

[WannabeOwner]

I think the 20 pannel is better..

25% more PV for £8% more

 

[ElectricPolice]

Million dollar question…

This is my story in an average-ish 4 bed detached house in an average housing estate.

To me battery capacity is more important than the extra solar. There’s only so much you can do with it (the solar). In the summer it maxes out the batteries quickly. On the worst winter days I’m lucky to generate 2-3kW (like yesterday) so the house lives mostly off battery storage from overnight charging. Trick is to balance usage and charge, but consider economies of scale otherwise the up front cost far far outweighs any returns. Even on my lowly 4.4kW south facing solar I export way too much in the summer and spend far too long trying to find things to wash, clean or charge. I tend to leave cars a little low (70%) in the summer to trickle a few kW into but solar is not my primary source for the cars, just a fall back when I’ve washed and dried everything.

I look at it like this now in the winter. Full charge overnight on my usable 11kW, which drains in the day, costs me £1.10 on IO but saves me £3.50 peak rate usage in the day. At current rates that’s £100 per month (rounded figures)

I’m not one of those who thinks about ROI but there comes a point when I’d rather spend my money on something else.

Fortunately we’re all happy in this house for overnight machine usage. I can run 2 dishwashers, 2 tumble driers and 2 washing machines staggered overnight. I make sure the filters are emptied every time. Basic maintenance. But that’s my personal choice, not up for debate. Electric usage for our house (charging 2 cars as well) per month over the last 3-4 months averages at around 1100kW per month. In the summer there is usually no overnight appliance usage as I want to max out the daily solar production.

Octopus compare app for the last 30 days has me at £181 per month on IO or £452 on flexible. Speaks for itself and that’s not including the solar 250kW average per month over the winter saving me another £100 per month.

Savings look loads better with current high prices than they did 2 years ago when I got the system installed but even so I’m loving it.

As regards the 3.68kW ceiling it’s something we have to live with, unless you go down the route of trying to get a bigger system approved. All adds time to the process I believe? Personally I just get over it. Sunday roast is going to peak at 5-6kW but it’s not constant. Ovens, hobs, microwave, plate warmers etc all heat cyclically and not continuously so it’s up and down so it keeps dipping in and out of full (solar=free) battery usage.

It takes a little patience to find the style that works for you and whether or not you might want to expand on storage in the future; however, someone wise on here said a while back make sure you get max solar at the same time to reduce costs for more scaffolding etc if you think you may upgrade in the future? Wise words.

Also birdproof your panels. My big mistake… cost me another chunk for scaffolding a year later

Sorry for the rambling, hope this helps?

 

[Drew57]

My 5kW PV system was installed in 2016 & at the same time I purchased a telescopic window cleaning brush (water feed when needed), sufficient length to reach the apex of the roof. It is used several times each year to wash/clean dirt build up and muck from the panels as well as for its original purpose on the windows.

Whenever we have snow it's also useful for clearing the panels, as used this morning so that rather than relying on any sun to slowly melt it, they can generate immediately at the maximum available.

The snow from last night laid nearly 2" deep on the roof but was removed earlier this morning & I already have <2.5kWh generation re filling the batteries (16.3kW).

The panels remain very clean to maintain maximum efficiency, we haven't paid for a window cleaner for the seven years since retirement and the brush more than paid for itself long ago. (...the only downside is a random voice in my ear reminding me to clean the windows more often than is really necessary but I am usually too feeble to resist).

 

[94jdh]

question, again.

Got quote:
- 10 solar panels on east facing roof, 10 on the west // (total 20). system size 8.2 kw
- Inverter: Lux Power 3.6 kw (LXP Hybrid)
- Battery: 9.6 kwh (3x LV--L3.2-1P
-------
13.5k

vs
- 6.56 kw system (16 pannels, 8 east 8 west)
- same inverter
- same battery
-----
12.5 k

I think the 20 pannel is better..
however I am worried about inverter size... 3.6 kw is more or less 1 kettle and a bit. if I have oven or washing - the pull from system exceeds the capacity. or do I read this wrong?

we are working from home and wife disagrees on washing machine/dryer running over night...

It does seem undersized but also depends on the pitch of your roof. There will potentially be clipping in summer/good weather at noon, but as the sun moves around the generation will increase on one and decrease on the other.
Personally a 5-6 kW inverter would be better, I'm guessing it's more of a case of the easier G98 application for the installer.

 

[yessuz]

i am new in this so please correct me if I am wrong here.

I am willing to go for 20 panels as it makes more sense, really. So the only question is inverter capacity and overall process

Inverter capacity is the total output it can sustain from the PV/Battery, correct? So let's say inverter is 3.6 kw. if my daily average draw is ~400 w, and if I turn on the kettle which is 3000 w, so the inverter will be on it's capacity limits at 3,4 kw, but still would draw from PV/Battery., correct?
If in the same time I turn on let's say toaster, then the load on the systems becomes 4.5 kw (assumption toaster is 1.1 kw) - in this case does it flip and consume from the grid, or how does it work?

At the same time, the power supply for my charger is after the meter (outside cabinet) - separate from the consumer unit (it has it's own breaker/fuse/automation). so basically after the meter power supply splits: one pole goes to charger, another - to consumer unit in utility room where all my breakers/fuses are located.
Solar would be feeding at the consumer unit, if I am not mistaken. so how would that work with the car?

Also, for trickle charge from solar - I have pod point charger - would I have to change it to zappi or something, or how do you deal with the PV output? are you limiting amperage on the car, or how does it work?

many thanks for information!

 

[94jdh]

i am new in this so please correct me if I am wrong here.

I am willing to go for 20 panels as it makes more sense, really. So the only question is inverter capacity and overall process

Inverter capacity is the total output it can sustain from the PV/Battery, correct? So let's say inverter is 3.6 kw. if my daily average draw is ~400 w, and if I turn on the kettle which is 3000 w, so the inverter will be on it's capacity limits at 3,4 kw, but still would draw from PV/Battery., correct?
If in the same time I turn on let's say toaster, then the load on the systems becomes 4.5 kw (assumption toaster is 1.1 kw) - in this case does it flip and consume from the grid, or how does it work?

At the same time, the power supply for my charger is after the meter (outside cabinet) - separate from the consumer unit (it has it's own breaker/fuse/automation). so basically after the meter power supply splits: one pole goes to charger, another - to consumer unit in utility room where all my breakers/fuses are located.
Solar would be feeding at the consumer unit, if I am not mistaken. so how would that work with the car?

Also, for trickle charge from solar - I have pod point charger - would I have to change it to zappi or something, or how do you deal with the PV output? are you limiting amperage on the car, or how does it work?

many thanks for information!

I'm not familiar with that inverter but yes you're likely to be limited to 3.6kWh either by max of batteries or combination of batteries and solar.
A larger inverter, like a 5kW Givenergy Gen2 can provide 5kW to house by use of 3.6kWh via battery and the difference by solar.
Yes, anything over and above the 3.6kWh draw in your case would be pulled from the Grid, which is why you'd benefit from a larger inverter. It also depends on how long the overage is to be sustained for.
In my case I two inverters, one for East and one for West, my Wallbox charger can have the amps turned down if necessary but I'm generally charging of night rate usually.

 

[phil4]

i am new in this so please correct me if I am wrong here.

I am willing to go for 20 panels as it makes more sense, really. So the only question is inverter capacity and overall process

Inverter capacity is the total output it can sustain from the PV/Battery, correct? So let's say inverter is 3.6 kw. if my daily average draw is ~400 w, and if I turn on the kettle which is 3000 w, so the inverter will be on it's capacity limits at 3,4 kw, but still would draw from PV/Battery., correct?
If in the same time I turn on let's say toaster, then the load on the systems becomes 4.5 kw (assumption toaster is 1.1 kw) - in this case does it flip and consume from the grid, or how does it work?

At the same time, the power supply for my charger is after the meter (outside cabinet) - separate from the consumer unit (it has it's own breaker/fuse/automation). so basically after the meter power supply splits: one pole goes to charger, another - to consumer unit in utility room where all my breakers/fuses are located.
Solar would be feeding at the consumer unit, if I am not mistaken. so how would that work with the car?

Also, for trickle charge from solar - I have pod point charger - would I have to change it to zappi or something, or how do you deal with the PV output? are you limiting amperage on the car, or how does it work?

many thanks for information!

Toaster/Kettle.... your use will be drawn as much as it can from Solar first... so if you're generating 3.6kW, and turn on the toaster, to take your use to 4.5kW, 3.6kW will come from solar and the other 0.9kW from the grid.

How/Where the solar goes into your system depends on what the installer does. Mine took the post meter tails, and wired everything (consumer, solar and car charger) in there... so the car charger can run off the solar, as well as the house doing the same. If you didn't want that, you'd need to ask your installer to wire it differently.

Charging I use a Zappi, it has CT Clamps round the house feed and solar so knows when and how much Excess there is, and adjusts the current accordingly. This time of year it's a full time job ramping it up and down. I've also a dumb Tesla wall charger, and don't use that for Solar. It's too much effort compared to letting the Zappi do it's thing.

The other upside of the Zappi is it's monitoring is much much better than my Inverter. Updating roughly every 10 seconds. And feeds into Home Assistant too.

 

[Cilonen]

i am new in this so please correct me if I am wrong here.

I am willing to go for 20 panels as it makes more sense, really. So the only question is inverter capacity and overall process

Inverter capacity is the total output it can sustain from the PV/Battery, correct? So let's say inverter is 3.6 kw. if my daily average draw is ~400 w, and if I turn on the kettle which is 3000 w, so the inverter will be on it's capacity limits at 3,4 kw, but still would draw from PV/Battery., correct?
If in the same time I turn on let's say toaster, then the load on the systems becomes 4.5 kw (assumption toaster is 1.1 kw) - in this case does it flip and consume from the grid, or how does it work?

At the same time, the power supply for my charger is after the meter (outside cabinet) - separate from the consumer unit (it has it's own breaker/fuse/automation). so basically after the meter power supply splits: one pole goes to charger, another - to consumer unit in utility room where all my breakers/fuses are located.
Solar would be feeding at the consumer unit, if I am not mistaken. so how would that work with the car?

Also, for trickle charge from solar - I have pod point charger - would I have to change it to zappi or something, or how do you deal with the PV output? are you limiting amperage on the car, or how does it work?

many thanks for information!

Afraid I can't answer re: the charger, but for the general load it will take the max inverter output (or whatever you've set, if lower) from solar/battery, & top up from the grid as needed.
The solar/battery will be your priority power feed, grid will be secondary, until solar stops generating or battery depleted.

 

[yessuz]

yes, already discussed with company and they will provide 5 KW inverter for small price increase - that will make much more sense.

so will have 20 panels + 5 kw inverter + 9.6 kw battery

all in 13,350 British dollars

sounds good?

now the only thing is to think how this would be installed the right way in order to be able to have few kw from solar into my car :/.. i can always use the travel charger, I suppose.

only thing is I want to avoid sucking from the batteries when car is charging over night (as I have once a week 40kwh+ charge over night

 

[ElectricPolice]

i am new in this so please correct me if I am wrong here.

I am willing to go for 20 panels as it makes more sense, really. So the only question is inverter capacity and overall process

Inverter capacity is the total output it can sustain from the PV/Battery, correct? So let's say inverter is 3.6 kw. if my daily average draw is ~400 w, and if I turn on the kettle which is 3000 w, so the inverter will be on it's capacity limits at 3,4 kw, but still would draw from PV/Battery., correct?
If in the same time I turn on let's say toaster, then the load on the systems becomes 4.5 kw (assumption toaster is 1.1 kw) - in this case does it flip and consume from the grid, or how does it work?

At the same time, the power supply for my charger is after the meter (outside cabinet) - separate from the consumer unit (it has it's own breaker/fuse/automation). so basically after the meter power supply splits: one pole goes to charger, another - to consumer unit in utility room where all my breakers/fuses are located.
Solar would be feeding at the consumer unit, if I am not mistaken. so how would that work with the car?

Also, for trickle charge from solar - I have pod point charger - would I have to change it to zappi or something, or how do you deal with the PV output? are you limiting amperage on the car, or how does it work?

many thanks for information!

Great responses for your other questions.

On your car charging point I tend to use the granny which runs at 10A so about 2kW. That way when the house is just ticking over I'm well within the limits of the inverter. If I use the wall charger then yes I turn the Tesla app down to 10-12A depending on how much I want it to draw and what else I'm using. I have it on a TCP smart switch so can turn it on via Alexa or the app when I want.

We have a Virgin Pure for hot water which boosts itself regularly so can occasionally top the 3.6kW but it's only a few seconds. Again not worth the stress to worry. Same with your kettle and toaster scenario, you're looking at minutes so that extra 1kW for your toaster over for 5 minutes let's say would be 41p / 12 = 3.5p. When you're factoring a £12.5-13.5k system it's peanuts.

 

[JIBYC]

question, again.

Got quote:
- 10 solar panels on east facing roof, 10 on the west // (total 20). system size 8.2 kw
- Inverter: Lux Power 3.6 kw (LXP Hybrid)
- Battery: 9.6 kwh (3x LV--L3.2-1P
-------
13.5k

vs
- 6.56 kw system (16 pannels, 8 east 8 west)
- same inverter
- same battery
-----
12.5 k

I think the 20 pannel is better..
however I am worried about inverter size... 3.6 kw is more or less 1 kettle and a bit. if I have oven or washing - the pull from system exceeds the capacity. or do I read this wrong?

we are working from home and wife disagrees on washing machine/dryer running over night...

Very similar position here - yes you will feel the effect and the 3.6kw inverter also caps battery discharge to 3kw making cooking difficult.

My suggestion would be to see if your DNO will give you approval for G99/5kw export for free which lets you take the 5kw inverter.

 

[ElectricPolice]

yes, already discussed with company and they will provide 5 KW inverter for small price increase - that will make much more sense.

so will have 20 panels + 5 kw inverter + 9.6 kw battery

all in 13,350 British dollars

sounds good?

now the only thing is to think how this would be installed the right way in order to be able to have few kw from solar into my car :/.. i can always use the travel charger, I suppose.

only thing is I want to avoid sucking from the batteries when car is charging over night (as I have once a week 40kwh+ charge over night

I set the inverter to charge from the grid for the last hour of IO to put a little juice in before the sun comes up. Car charging empties everything hence putting 3-5kW into the batteries by 5:30 supplies the house early morning.

Unless you get your system wired to avoid/bypass each other (no idea how that's done in a normal setting but many on here have it set that way)?

It's a swings and roundabout thing. Either solar power or cheap rate. Main plan is to avoid peak rates at all cost. Better to play safe and charge the batteries off peak than have them run out and use peak.

 

[ringi]

question, again.

Got quote:
- 10 solar panels on east facing roof, 10 on the west // (total 20). system size 8.2 kw
- Inverter: Lux Power 3.6 kw (LXP Hybrid)
- Battery: 9.6 kwh (3x LV--L3.2-1P
-------
13.5k

vs
- 6.56 kw system (16 pannels, 8 east 8 west)
- same inverter
- same battery
-----
12.5 k

I think the 20 pannel is better..
however I am worried about inverter size... 3.6 kw is more or less 1 kettle and a bit. if I have oven or washing - the pull from system exceeds the capacity. or do I read this wrong?

we are working from home and wife disagrees on washing machine/dryer running over night...

Is there a reason for not having the 5kw version of the inverter?
Putting 8.2 kw of panels on the 3.6kw inverter needs confirmation in writing the inverter warranty covers it.
I would go for the 20 panels.

 

[yessuz]

Is there a reason for not having the 5kw version of the inverter?
Putting 8.2 kw of panels on the 3.6kw inverter needs confirmation on writing the inverter warranty covers it.
I would go for the 20 panels.

it's been upgraded to 5 kw inverter in the quote and 5 KW I would go for.

for me now the only remaining question is this scenario:

I get back in the evening, 6 pm, with car needed 40 kwh to charge. Batteries by that time are more or less full. Sun goes down, so in this car, my car with IO would start ~23:00. I would get off-peak rate from then as well.. so if I understand correctly, once car starts to pull 7 kw, I have about 1 hour of batteries, and then it is empty (or empty earlier. but overrall house usage would still be max at off-peak rate.

even if I have only half of battery remaining, so let's say 4 kwh, then car would suck it in 30 minutes and then flip to off-peak rate...
however in this case, most probably, I would have to dumb down IO and set the scheduled charging to start 23:30..

sounds like a plan.. unless I miss something.

 

[ringi]

One option is to split the main cable before the current sensor for the inverter so the inverter does not see any power the car takes.

 

[Drew57]

As well as a Zappi charger, I've got two separately configured battery based systems which suit my situation very well.

1. 3.6kWh Solax inverter & 5.25Kw PV panels feeding 6.7kW LG batteries.
   - This system is wired 'upstream' of the CU so any car charging at full 7kWh would in theory drain the batteries above 3.6kWh draw but the inverter is permanently set to block discharge during IO off peak hours 23.30-05.30 to avoid this (ie when the Zappi DOES require +7kWh).
   - If any additional IO slots are given pre 23.30 I add further temporary block discharge settings, however 95% of the time the standard 6 hours cover everything.
   - The LG batteries only charge via solar.
   - The cars charge mostly from off-peak grid during winter.
   - The system batteries never force charge from grid, only solar.*
   
   
2. 3.6kWh Lux inverter & 9.6kW Pylontech batteries.
   - This system is wired 'downstream' of the CU so any car charging happens independently & could never drain these batteries.
   - The inverter is also set to block discharge during IO off peak hours 23.30-05.30 (although spring>summer>autumn this isn't used as both sets of batteries normally fully charge via solar so only drain slightly overnight).
   - During winter these batteries are set to charge 23.30-05.30 using IO off-peak so a guaranteed 9.6kW is always available next morning (plus whatever is remaining from the LG batteries, usually +50%)
   - During spring >summer>autumn the Pylontech batteries mostly charge using excess solar.
   - The cars charge mostly from solar spring>summer>autumn.
   - The system batteries charge from both grid and solar.

• We never need peak grid usage during any season apart from ~40-50w background, powering whichever inverter is active at the time.
• Car charging never affects either set of battery SOC.
• In winter all other high usage devices (dishes/washing/tumbling/hot water storage etc) are set to run 23.30-05.30 at off peak rate.
• In spring>summer>autumn these devices plus various others that are battery powered (ie lawnmower) all use excess solar.

*It was the 'incorrect' configuration of my original FIT meter that caused me to require a second system to enable force battery charging using off-peak grid. By accident rather than design this has resulted in a flexible & configurable setup with two sets of batteries that can be controlled independently (& the Lux inverter/Pylontechs will operate off-grid during any power cut).

It may sound complicated but only the second system needs slight changes to settings for each particular season. The settings for the PV system almost never change & for car charging we only use 'Fast' for overnight charging or Eco+ with solar.

 

[Gadgetman67]

yes, already discussed with company and they will provide 5 KW inverter for small price increase - that will make much more sense.

so will have 20 panels + 5 kw inverter + 9.6 kw battery

all in 13,350 British dollars

sounds good?

now the only thing is to think how this would be installed the right way in order to be able to have few kw from solar into my car :/.. i can always use the travel charger, I suppose.

only thing is I want to avoid sucking from the batteries when car is charging over night (as I have once a week 40kwh+ charge over night

Intresting as I'm in the same situation, but a few steps behind you. How long do you think pay back will be roughly?

 

[yessuz]

Intresting as I'm in the same situation, but a few steps behind you. How long do you think pay back will be roughly?

need to do the man maths

but with 42p of IO Peak price, should be quick,,,

 

[OneTinyFish]

I'm going to answer the OP's question...

...in the form of interpretive dance...

I'm on the Isle of Man, which is NW England/Scotland/Ireland (ish) for those who don't know. We're windy - and cloudy. And as I type this, quite wintery too.

The Solar Panels and Powerwalls have been a fantastic investment. We had them - 13.51kWp of solar panels spread across E/W mostly, and 2 x Powerwall 2 (27.5kWh storage). And... from July when prices go up, we will have broken even on the monthly repayments. Yes, I financed them over ten years. All the details, including the maths are in the video above.

Hope this helps!

Mike