Solar Panels UK - is it worth it?

[thewishy]

Wondered if anyone has used Octopus for solar install and any good/bad points and if the cost is reasonable?

Octopus did my install.

• Prices are generally good, but not to the level where they've got to cut significant corners. You will find cheaper if you hunt around (particularly schemes like Solar Together)
• The Givenergy kit is pretty decent price for performance. Again, Octopus are looking for "good but not premium"
• The process went smoothly, MCS packs got sent promptly, they got my export meter sorted fairly quickly and without much fuss
• Octopus do not subco, the installers were octopus employees, all very nice and the quality of work was (IMHO) good
• Their estimated production was scarily similar to what was actually produced last year
• Octopus are looking to do a "standard install", which means they're not interested in dealing with things like EPS or complex installs
• Octopus aren't likely to go anywhere as a company, and while they're not perfect, they do have a complaints handling system which mostly works and they do tend to do the right thing. This was the main attraction for me, I don't want it installed by a company that goes bust 2 months later

On the install spec. It's quite a small install they're doing, but the price is also pretty attractive. I can't figure how they come to 94% self consumption if they're not including a battery with the kit. Generally I would say that a battery is *really* worthwhile for the payback case.

• It's a bit of a grey day today, I was pulling about 1500w this morning. With a battery that means running the kettle/oven is partly battery, partly solar, zero grid. It makes little sense pulling 1kw from the grid @28p/kWh one minute and then exporting back to the grid @15p/kWh the next minute
• In the winter, the battery saves me far more than the PV panels
• Battery was also super helpful for savings sessions (Made about £120 with little effort)
• Retrofitting a battery later will be a pain. It's a simple add-on for the hybrid inverter, but you'd need a givenergy installer to put it in

I would personally try for at least a 5.2kWh battery, if not 9.5kWh. But even the small 2.6kWh battery will help you

On solar in general, electric prices don't seem to be coming down that much, and at the moment I'm looking at a 6-7 year payback

 

[phil4]

I'd second the idea of a battery, having run for 6 months without. Depending on your circumstances it can smooth solar so you use all of it, whether the clouds come and go or you put the kettle on. Or if you've got it big enough to cover your day's use without solar, you can go on IOG, charge it for 7.5p, run off it all day, and export solar (and any left over in the battery) for 15p. In order to size it look at what your normal daily usage is, and if you can remove any car charging and the 6 hours overnight, then get something that can cover all that use. If that's too expensive/too big, just get what you can, the smoothing of the solar will make it beneficial.

 

[thewishy]

I am wondering if the latest discussions around batteries in lofts might be causing Octopus to hesitate slightly on pushing batteries...

 

[Simon Watts]

Ideally would like to go with a battery as well but even just 6 panels is going to take some hard selling tactics.

Octopus did say that regulations are changing with batteries. Soon batteries can only be installed outside. Did wonder if I could go with battery only but was told by another company that it would be very tricky to add solar afterwards.

 

[Tony Hoyle]

"Soon batteries can only be installed outside."

Ouch. If I ever pull the trigger on a battery that's going to have to happen before then otherwise it means no battery would be possible.

 

[Drew57]

Did wonder if I could go with battery only but was told by another company that it would be very tricky to add solar afterwards.

Why?

I installed a battery-only setup several years ago (additional to the main FIT solar/hybrid/battery system which I already have) then added solar to it in 2022 using a different installer.

It was a simple and trouble free process with a CT clamp from the battery inverter to the panel inverter being the only interface needed.

 

[thewishy]

Ideally would like to go with a battery as well but even just 6 panels is going to take some hard selling tactics.

I'd argue that with the smaller array, a large battery is a bigger benefit, as you'll probably want to top up overnight

The batteries outside - there is a new draft British Standard which "ban them" from lofts, escape paths and rooms with people in them. Garages are largely OK.
An inverter is generally best placed in the loft, because it minimises the DC cable run (DC cables are more of a concern than AC because you can't use RCDs on them), hybrid inverters are a super cheap way and efficient for that inverter to be able to use a battery. But if Inverters belong in Lofts and Batteries don't, the current hybrid inverter designs will be much harder to fit.

 

[Js1977]

Just looking for some advice.
Had a quote from Octopus for 6 panels, 2.610kW (max number can fit on main roof) at a cost of £4,299. This includes savings of £1500 due to Octopus Spring sale.

Believe the panels are JA Solar 435 watt with an GivEnergy 1PH Hybrid Inverter 3.6kW.

Wondered if anyone has used Octopus for solar install and any good/bad points and if the cost is reasonable?

They provided the following graph. Wondering if it’s worth it. Any help would be great.

View attachment 1043386

Ive just had this very recent quote but do bare in mind that the install would only require a small tower being erected... £3930

Supply and Installation of Enphase PV system 2.58kWp capacity
Installation of 6 x Jinko 430Wp all-black panel matched with 6 Enphase IQ8 (Q8MC-72-M-INT ) inverters to connect to existing Gateway. NOTE - maximum 11 panels on a single Fused connection

With the existing PV and Powerwall system, this PV installation exceeds the 16amp limit set by the "Connect and Notify" scheme and so will be subject to Grid Operator approval prior to installation.

Roof Pitch 8 degrees, Roof orientation at 0 degrees off south. Zero shading. Annual output 2363kWhours

Includes:

• Supply and installation of Solar PV panel and micro-inverters
• All roof to ground cabling and necessary containment
• Connections to existing Meter Point/Distribution Board
• Electrical certifications and Building Control notification as required
• District Network Operator notification
• Handover pack
• Insurance backed 5 year installation workmanship warranty

 

[thewishy]

Ive just had this very recent quote but do bare in mind that the install would only require a small tower being erected

How much was the quote

Also note the enphase inverters, which tend to be more expensive as a solution, but for a small set of panels might actually work out cheaper, especially if you already have a gateway in place. The enphase stuff is good, but it's not as easy to attach batteries directly to

 

[Js1977]

How much was the quote

Also note the enphase inverters, which tend to be more expensive as a solution, but for a small set of panels might actually work out cheaper, especially if you already have a gateway in place. The enphase stuff is good, but it's not as easy to attach batteries directly to

Sorry about that. Post edited.

The enphase stuff is good, but it's not as easy to attach batteries directly to

Very easy and less hassle I would say since it just connects straight to the existing AC. My neighbour has a DC setup and has more equipment. Mine is a much neater install and required much less area. Obviously at a price...

 

[JIBYC]

Sorry about that. Post edited.



Very easy and less hassle I would say since it just connects straight to the existing AC. My neighbour has a DC setup and has more equipment. Mine is a much neater install and required much less area. Obviously at a price...

I quite like a DC / hybrid setup as it allows you to generate more than your DNO export limit by pushing the excess into the batteries on the DC side.

 

[Js1977]

I quite like a DC / hybrid setup as it allows you to generate more than your DNO export limit by pushing the excess into the batteries on the DC side.

Ive never heard of this and cannot test it since my solar system even when upgraded will not constitute to the export limit (6kw) . However my logic is that being that I can charge the batteries at 10kw (from the grid) and discharge at the same rate internally, I can only assume that should the solar be able to give me 15kw and my batteries where at a low enough state of charge, I would get 10kw to the house/batteries and the rest would be exported (5kw). Also a benefit with my system at least is t that the solar keeps working even if the grid is down.

 

[RedMod3]

I'd argue that with the smaller array, a large battery is a bigger benefit, as you'll probably want to top up overnight

The batteries outside - there is a new draft British Standard which "ban them" from lofts, escape paths and rooms with people in them. Garages are largely OK.
An inverter is generally best placed in the loft, because it minimises the DC cable run (DC cables are more of a concern than AC because you can't use RCDs on them), hybrid inverters are a super cheap way and efficient for that inverter to be able to use a battery. But if Inverters belong in Lofts and Batteries don't, the current hybrid inverter designs will be much harder to fit.

Not sure I like inverters in the loft as my loft used to hit 46C in the hot summer. My 2013 Fronius inverter was put in our garage, and yes, we have rather long DC cable runs, but the inverter keeps the garage warmer in winter and doesn't overheat in summer which is why it may have lasted 11 years so far. Also, I sometimes need to reconnect the CAT6 cable to it, and it is far easier to maintain in the garage than the loft.

 

[thewishy]

So with the hybrids, the DC-DC for the battery is separate from the DC-AC inverter. So if you have a 4kw array and a 3.6kw inverter, in principle you could feed some power to the battery (if it's not full) while doing max export. The only difficulty being that it's hard to control the inverter so that it stops topping off the battery while leaving some capacity to fill the battery from this excess (unfortunately, not possible with Giv as far as I'm aware).
The DC-DC is also a little more efficient at storing your PV as it's DC-DC, not DC-AC-DC. That said, it's not making a lot of difference for me at the moment as I'm topping up overnight from octopus IO at 7.5p and exporting during the day at 15p - thanks octopus - although this probably won't last forever.

In Simon's case, it's not really important as 2.6kWp won't exceed the 3.6kw of the inverter under any circumstances (A cold bright day can exceed the rating, I've seen 4.4kw from my 3.95kWp)

The enphase stuff is neat, and works really well if you have a power wall or similar. For a smaller number of panels, it might be cheaper than a monolithic inverter if you don't want a battery. But I don't think Octopus fit them..

Long DC runs to a monolithic inverter are out of fashion as regulations have evolved - the cables would need a metal enclosure if it goes through any living space. Inverter manufacturers have designed the inverters to be relatively happy in a loft - they have big chunky heatsinks and will throttle if the worst comes to the worst. I can see the logic of "cool electronics last longer", but end of the day I have a 10 year warranty on the install, by which time I've had a full payback on the system

 

[GRiLLA]

So with the hybrids, the DC-DC for the battery is separate from the DC-AC inverter. So if you have a 4kw array and a 3.6kw inverter, in principle you could feed some power to the battery (if it's not full) while doing max export. The only difficulty being that it's hard to control the inverter so that it stops topping off the battery while leaving some capacity to fill the battery from this excess (unfortunately, not possible with Giv as far as I'm aware).
The DC-DC is also a little more efficient at storing your PV as it's DC-DC, not DC-AC-DC. That said, it's not making a lot of difference for me at the moment as I'm topping up overnight from octopus IO at 7.5p and exporting during the day at 15p - thanks octopus - although this probably won't last forever.

In Simon's case, it's not really important as 2.6kWp won't exceed the 3.6kw of the inverter under any circumstances (A cold bright day can exceed the rating, I've seen 4.4kw from my 3.95kWp)

The enphase stuff is neat, and works really well if you have a power wall or similar. For a smaller number of panels, it might be cheaper than a monolithic inverter if you don't want a battery. But I don't think Octopus fit them..

Long DC runs to a monolithic inverter are out of fashion as regulations have evolved - the cables would need a metal enclosure if it goes through any living space. Inverter manufacturers have designed the inverters to be relatively happy in a loft - they have big chunky heatsinks and will throttle if the worst comes to the worst. I can see the logic of "cool electronics last longer", but end of the day I have a 10 year warranty on the install, by which time I've had a full payback on the system

My Sunsynk will also do DC to DC into the battery, so I've occasionally seen more than the inverters rating of solar being consumed, it's rare though as you need significant house load, charging batteries and lots of sun.

It, and the 2 batteries are in the loft mounted on the gable wall, I really don't see how this will be a problem. Its a reliable system, I've never needed to physically access it yet other than when I hacked a Pi running solar Assistant to give me real time data.

 

[phil4]

My Sunsynk will also do DC to DC into the battery, so I've occasionally seen more than the inverters rating of solar being consumed, it's rare though as you need significant house load, charging batteries and lots of sun.

It, and the 2 batteries are in the loft mounted on the gable wall, I really don't see how this will be a problem. Its a reliable system, I've never needed to physically access it yet other than when I hacked a Pi running solar Assistant to give me real time data.

I think a good many HYbrid inverters can do DC-DC direct to the battery.

Mine isn't hybrid, but is mounted in the loft... albeit it's a doddle to access, ladder, carpeted flooring, properly lit etc.

 

[thewishy]

Being able to do the DC-DC shunt is the definition of a hybrid inverter, and the shared AC-DC inverter saves a good deal of manufacturing costs too.

The British Standard focusing on "no batteries in lofts" is focusing on a few areas
1) Fire risk, obviously. Although manufacturers argue that LFP makes the risk pretty low. That's why they're saying they shouldn't be put, say, under stairs where the stairs are the main escape way, or in bedrooms where people might be overcome by fumes early in to a fire.
2) Building collapse risk, which is more when the loft comes in. An LFP battery is unlikely to cause a fire, and a fire in a loft (With a smoke alarm fitted) is unlikely to result in difficulty escaping from the building. But lets say there is another cause of the fire, what's the battery attached to, is it fire resistant and will a firefighter coming in from a rescue have 100kg of battery land on them if the installer just attached it to some plyboard.

They're things to think about, but on the other hand, there are no rules on where tumble dryers or fridges are located, and they cause many more fires.

I can see that outside the lowest risk option, but LFP really doesn't like the cold, so...
My octopus install is on a ~12mm ply board, which is firmly attached to the gable A frame and possibly some brickwork. So in principle risk 2 could happen, but with a set of decent interlinked smoke alarms, it's unlikely that we'd be unable to get out and would require rescue

 

[GRiLLA]

Being able to do the DC-DC shunt is the definition of a hybrid inverter, and the shared AC-DC inverter saves a good deal of manufacturing costs too.

The British Standard focusing on "no batteries in lofts" is focusing on a few areas
1) Fire risk, obviously. Although manufacturers argue that LFP makes the risk pretty low. That's why they're saying they shouldn't be put, say, under stairs where the stairs are the main escape way, or in bedrooms where people might be overcome by fumes early in to a fire.
2) Building collapse risk, which is more when the loft comes in. An LFP battery is unlikely to cause a fire, and a fire in a loft (With a smoke alarm fitted) is unlikely to result in difficulty escaping from the building. But lets say there is another cause of the fire, what's the battery attached to, is it fire resistant and will a firefighter coming in from a rescue have 100kg of battery land on them if the installer just attached it to some plyboard.

They're things to think about, but on the other hand, there are no rules on where tumble dryers or fridges are located, and they cause many more fires.

I can see that outside the lowest risk option, but LFP really doesn't like the cold, so...
My octopus install is on a ~12mm ply board, which is firmly attached to the gable A frame and possibly some brickwork. So in principle risk 2 could happen, but with a set of decent interlinked smoke alarms, it's unlikely that we'd be unable to get out and would require rescue

Indeed, my installers fitted a battery powered smoke alarm, but I've added a heat alarm that's interlinked with the rest of the house. The installer first just stood the batteries on the rafters, but I complained and then came back to fit them through the backing board into the wall. Absolutely no complaint, it should have been done that was from the start.

I'm happier with that arrangement than having long DC cables to the garage, that seems like a higher risk to me, not an easy route due to the T shaped house,

 

[thewishy]

I suspect that well secured to the A frame is unlikely to fail in all but the most extreme circumstances, but the standard will assume bad workmanship and that 100kg of battery will just be left on the rafters

 

[Hook]

One thing I would advise is also to consider lower capacity panels. You may find that because they're smaller than the larger ones, you can actually get more of them up on your roof and have more capacity.

So make sure you know your roof capacity.