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Solar Panels UK - is it worth it?
- Thread starter jdwuk
- Start date
Undecided_2
Member
I’m on Octopus Fixed export and it’s been bumped to 15p per kW. Although, I’m moving to the agile as it may be a higher average.
WannabeOwner
Well-Known Member
DNO permission required? (IDK). If so maybe they will move the goalposts between now and then. I'm surprised how much the DNO let me have, but maybe I was first-kid-on-the-block
not quite pylontech - I think they recommend an electrician - but it seems pretty simple.
Hey all, I am a newbie in the world of solar power and have no idea which kit I should be going with. I got 2 quotes
From SunSave:
13x LONGi Panel, total 5.265kW
Huawei 5kW Inverter
Huawei 5kWh battery
Total cost: £11,322
From Otovo:
13x Trina Panels, total 5.4kW
Growatt 8kW Inverter
Pylontech 10.12 kWh battery
Total Cost: £12,107
I am quite confused and have a couple of questions:
From SunSave:
13x LONGi Panel, total 5.265kW
Huawei 5kW Inverter
Huawei 5kWh battery
Total cost: £11,322
From Otovo:
13x Trina Panels, total 5.4kW
Growatt 8kW Inverter
Pylontech 10.12 kWh battery
Total Cost: £12,107
I am quite confused and have a couple of questions:
- Which system should I go with?
- Does anyone have any experience with Otovo/Sunsave. How their wormanship etc. is?
- Is there any other provider/installer I should get a quote from?
- I am leaning towards the Otovo designed system, should I request them to change any part of the kit to some other better brand?
More is more. That otovo quote looks a significant step up - better panels, double the battery for only a small cost increase. That will save you significantly more £££ over the years.
Unless something else stands out as sub par (warranty? Sales guy creeped you out?) Can't think of any reason not to go with the better solution.
phil4
Member
Start with working out what you use on most days, you should be able to do this from your monthly bill either as a broad average of the month, or by looking at the days.
If you can, remove any car charging from that.
Then for Solar go for as much as you can from the panels, and get an inverter as close to that output. Finally try and find a battery close to your daily usage as you found above, or a bit more if possible. The idea being the battery will in winter be able to power you through the day when charged off peak at night.
There's more subtleties like the charge and discharge rate of the battery, eg. if it's 15kWh, but can only charge at 3kW, then it'll need 5 hours off peak, so won't work with Go. Likewise 3kW may not power, for example your kitchen hob and oven in the evening, so you'll be on peak rate for the bit over. So try and get something with charge and discharge rates that would work for you.
If you can, remove any car charging from that.
Then for Solar go for as much as you can from the panels, and get an inverter as close to that output. Finally try and find a battery close to your daily usage as you found above, or a bit more if possible. The idea being the battery will in winter be able to power you through the day when charged off peak at night.
There's more subtleties like the charge and discharge rate of the battery, eg. if it's 15kWh, but can only charge at 3kW, then it'll need 5 hours off peak, so won't work with Go. Likewise 3kW may not power, for example your kitchen hob and oven in the evening, so you'll be on peak rate for the bit over. So try and get something with charge and discharge rates that would work for you.
that inverter is odd for that solar setup - would seem to be more efficient to go smaller? Also both are more than 3.68kw standard so you may need additional permission to export more than that (or may have to consider a 3.68kw inverter to prevent that).
second one has almost twice the battery and definitely I’d lean that way. If its sunny you don’t need a ‘full day’ usage in your battery just enough to get you through from sunset to sunrise, but bigger is better for winter usage if you have a cheaper overnight rate to reduce peak grid use, or to cycle less
second one has almost twice the battery and definitely I’d lean that way. If its sunny you don’t need a ‘full day’ usage in your battery just enough to get you through from sunset to sunrise, but bigger is better for winter usage if you have a cheaper overnight rate to reduce peak grid use, or to cycle less
Undersizing is common practice. 99.9% of the time you won’t achieve the full array output and a smaller inverter is often more efficient at lower outputs.
Is this true with MicroInverters also?
My quotation is for 1 IQ7PLUS-72-2-INT behind every panel.
The ‘premium’ panels are 420w peak output, but the MicroInverters seem to cap out at 295w. Not sure I understand the logic of going for the ‘better‘ panels (eg vs a 385w max output cheaper panel) with these inverters - unless the premium panels offer more in lower insolation days??
I'm doing mine this weekend..
My sparky mate, MCS registered etc, has suggested that I don't grind out the back of the tiles, where the hooks come through.
I'm doubtful and may compromise and gob up around the gap.
What with 90% of my roof being panelled, I'm not sure ..if at all..if there is a risk of rain penetration.
Thoughts?
phil4
Member
It's a good idea. If you don't the tile doesn't sit flat. This will allow wasps and the like easier access.
It'll also put pressure on the weaker part of the tile joining to the side.
Added risks, as opposed to "won't work unless you do".
phil4
Member
I think that's now slightly outdated advice. If you look for example at the range of Solis inverters, the start-up voltages are the same for all but the tinniest (some 1kW one). So if tied to 5kW of solar, a 3.68 will fire up at the same voltage as the 5kW or the 6kW. So no real advantage to going smaller.
That said, I'd not go with 8 in 5 as you're paying extra for the extra capacity, which you'll never use. FWIW at peak I get 5.43kW (my array is nominally 5.33kWp) on a 5kW inverter.
Presume that was Octopus who didn't want to install north facing? Yes, they definitely want nice standard Solar installs, the same as they want nice standard EV charger installs, and will work a little to customise heatpumps, but really they don't want to get involved with anything special.
For solar, If you've got a standard house with a southish facing roof which is in a good state, they provide something decent at a reasonable price. My guess is they didn't want to provide something with a long payback and lower production, and risk complaints around a miss-sale later - for every competent person who can make adult decisions, there is probably another who will feel sour about the experience later.
I believe someone has to do their training course before they can access the site that allows an installer to commission a new battery, ie make the inverter aware of it.
It won't be a huge job. Just remember that the Givenergy Gen1 hybrid inverters only do 2.6kw batter charge/discharge, and as you increase the battery capacity this becomes more and more of a limitation for charging off peak. The Gen2 units have 3.6kw chargers (And a heap of firmware qwerks right now)
No DNO permission required for changes to battery configurations, as only the inverter actually interacts with the grid.
One other reminder, batteries purchased at the time of a solar install are 0% VAT. Batteries bought on their own (Retrofit to an existing system, or just coupled AC) are 20% VAT. So it pays to err on the size of bigger and get it all done in one go
so my house fuse tripped and I switched back on, but my old PV fuse in the CU has tripped. Tried turning it back on and it tripped the house again.
installers swear they havne’t turned anything on, not been near the old panels, nothing is wired in. Just the weirdest coincidence?
Not even sure how it gets maintained as its a leased system. Sods law if my old array breaks just as my new one gets put in
edit: possibly the installers may have nudged the old wire - the original installers (10 years ago) apparantly just slung it over the roof and then through a soffit somewhere to get down to the meter cupboard so I suppose I should be surprised its lasted this long!
installers swear they havne’t turned anything on, not been near the old panels, nothing is wired in. Just the weirdest coincidence?
Not even sure how it gets maintained as its a leased system. Sods law if my old array breaks just as my new one gets put in
edit: possibly the installers may have nudged the old wire - the original installers (10 years ago) apparantly just slung it over the roof and then through a soffit somewhere to get down to the meter cupboard so I suppose I should be surprised its lasted this long!
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A few pages ago I mentioned we were having Waste Water Heat Recovery fitted (WWHR). I thought it was time to do a short write up on it.
We were having the upstairs bathroom redone, and having seen WWHR mentioned somewhere (one of our EPC's possibly, not sure) I looked into it, not having heard anything about it before. Some man math later, and it looks like a retro-fit can save about ~1/3rd the hotwater use of a shower (designed into a building it can be as much as 2/3rds!), and pay back in around 2 years! Looking online, this seems to have won out as the device of choice, at least for horizontal under bath fitting: Recoup Easyfit+ - Under bath waste water heat recovery system and is actually avaliable via Jewsons and other building merchants.
The idea is that it uses the heat of the water going down the drain from a shower to pre-heat the cold supply into a mixer shower. This lets you reduce the amount of hot water being used to get to a given temprature, reducing your overall usage and saving the cost of heating that power. This is really important for people with heatpumps, as our water will probably only be at ~45-50 deg c, which means you mix in a very small amount of cold to get to the 40 needed for a shower. This then means you use a lot of water, and I much preffer to have the HW on once or twice a day at either cheap power time or high solar and high out side temp time as this keeps my costs down. Getting 4 of us through a shower on 1 tank would be significantly advantageous.
It fits like this - just an extra device under the bath. Drain goes through it then out under the floor, and cold water supply to the tap/shower goes via it. Plumber just added it in as part of the fitout.
excuse the terribe photo - I had to mess with the exposure etc to be able to see the black slice under the bath at all!
And it seems to be working. This is a picture of the downstairs shower, no WWHR:
That cold side of the tap/shower mixer is bringing water in at ~9 deg c. That end of the mixer bar is covered in condesation and feels cold to touch.
This is the new one upstairs with the WWHR fitted, hot input on the left, cold on the right. 'Cold' is coming in at 24 deg c! Slightly generous contrived scenario as the shower is running its 40 degc water almost straight into the plug hole for the pictures (taking pictures of a shiny thing, even in IR, while in the shower seemed like a bad idea. We all remember the ebay kettle, right?). By the time it's washed a person and sloshed around the bath a little I expect what actually goes down the plug hole to be a bit cooler and the input therefore not quite so warm. It is still noticibly warm to touch while showering.
Finally, does it save us anything? Well, it seems so! Luckally we started using the new bathroom around the start of this month
Thats £70 vs £42. Curcimstantial evidence suggests this is also pretty generous (March was pretty cool, April has been mostly warm which helps the heatpump, but whatever numbers I look at, we are definitly saving something).
Anyway, thought it worth writing up. For £500, it seems a worth while addition if you are looking for another way to reduce costs in the long run.
We were having the upstairs bathroom redone, and having seen WWHR mentioned somewhere (one of our EPC's possibly, not sure) I looked into it, not having heard anything about it before. Some man math later, and it looks like a retro-fit can save about ~1/3rd the hotwater use of a shower (designed into a building it can be as much as 2/3rds!), and pay back in around 2 years! Looking online, this seems to have won out as the device of choice, at least for horizontal under bath fitting: Recoup Easyfit+ - Under bath waste water heat recovery system and is actually avaliable via Jewsons and other building merchants.
The idea is that it uses the heat of the water going down the drain from a shower to pre-heat the cold supply into a mixer shower. This lets you reduce the amount of hot water being used to get to a given temprature, reducing your overall usage and saving the cost of heating that power. This is really important for people with heatpumps, as our water will probably only be at ~45-50 deg c, which means you mix in a very small amount of cold to get to the 40 needed for a shower. This then means you use a lot of water, and I much preffer to have the HW on once or twice a day at either cheap power time or high solar and high out side temp time as this keeps my costs down. Getting 4 of us through a shower on 1 tank would be significantly advantageous.
It fits like this - just an extra device under the bath. Drain goes through it then out under the floor, and cold water supply to the tap/shower goes via it. Plumber just added it in as part of the fitout.
excuse the terribe photo - I had to mess with the exposure etc to be able to see the black slice under the bath at all!
And it seems to be working. This is a picture of the downstairs shower, no WWHR:
That cold side of the tap/shower mixer is bringing water in at ~9 deg c. That end of the mixer bar is covered in condesation and feels cold to touch.
This is the new one upstairs with the WWHR fitted, hot input on the left, cold on the right. 'Cold' is coming in at 24 deg c! Slightly generous contrived scenario as the shower is running its 40 degc water almost straight into the plug hole for the pictures (taking pictures of a shiny thing, even in IR, while in the shower seemed like a bad idea. We all remember the ebay kettle, right?). By the time it's washed a person and sloshed around the bath a little I expect what actually goes down the plug hole to be a bit cooler and the input therefore not quite so warm. It is still noticibly warm to touch while showering.
Finally, does it save us anything? Well, it seems so! Luckally we started using the new bathroom around the start of this month
Thats £70 vs £42. Curcimstantial evidence suggests this is also pretty generous (March was pretty cool, April has been mostly warm which helps the heatpump, but whatever numbers I look at, we are definitly saving something).
Anyway, thought it worth writing up. For £500, it seems a worth while addition if you are looking for another way to reduce costs in the long run.
They can be installed in different ways - the more efficient way is to feed your combi or other boiler but that is a massive plumbing project. The way I have it its just in the bathroom, and this would work for any heat source.
WannabeOwner
Well-Known Member
I expect I'm being really REALLY dense ... yeah, I hear you all .. ."as usual"
I get that the waste water can pre-heat the cold feed.
How does that reduce hot water consumption?
It seems to me that I either blend red-hot-water (from my hot pipe feed) with a tiny little bit of stone cold water, to get the perfect temperature ... or blend it with a lot of tepid water (from the heat recovery system).
I'm not seeing how that reduces the amount of hot water I use?
(I can imagine it makes it a lot easier to adjust to get the mix right, because trying to do the stone-cold-water mix, with the accompanying problem of the cold being at mains pressure, makes it difficult to get "just enough" cold ... so I presume tepid water provides a much less fine-grained control
I can also see it would make a huge difference to an in-line electric heater for a shower - the sort that is only plumbed to cold feed and heats the water in-real-time (using so many kW that it is not possible to charge an EV at the same time ...)
Pls enlighten me on the bid I have overlooked
