The Solar Thread

Fwiw, I’m not convinced solar thermal is cost effective. Assuming annual servicing to keep glycol topped up & pressured correctly.

Yeah – I think you’re right about cost effectiveness.

(The rest of the post is personal to my situation but it might help others with their thinking): I had a solar tank fitted a while ago; I faced installing a couple of shower pumps to boost shower pressure or fit an unvented cylinder, or fit a combi boiler. Given that a new boiler at this time is a bit ‘iffy’ with the gas situation, I decided to go with the cylinder option and to pay a small amount more to fit a solar-capable one. I also figured that when it comes to replacing the current gas boiler it may very well be ASHP and therefore keeping a HW cylinder in situ would mean the investment would have a longer working life.

So to fit the Solar thermal panel I DIY’ed it using a kit from Stoves and Solar (kit price £1650) and a roof access scaffold tower (hire cost £350), so the incremental cost was £2k to add the panel to my system. In terms of operating costs, I have solar PV and the pump maxes out at 40 watts so essentially ‘free’ to run. Maintenance will also be DIY. I’m not trying to claim any kind of Renewable Heat Initiative funding etc.

Mines in Aberdeen. – about 10 miles inland away from the worst of the haar

Worth checking your inverter can’t take a plug in data logger. Many can.

My inverter lives in the attic also but it logs to an app via IoT

Fwiw, I’m not convinced solar thermal is cost effective. Assuming annual servicing to keep glycol topped up & pressured correctly.

Not much different to keeping a boiler topped up.

Then you have to factor in you’re running a pump during daylight hours. Over complicated tech that no heating engineer wants to go near in my experience.

I am surprised at that they are definitely not complicated. If a heating engineer can’t understand a solar thermal solution they are not a heating engineer!

My PV to immersion boost provides me with more hw than thermal panels ever did.

Must have been something wrong because the effectiveness of solar thermal much higher.

Can I kindly request that anyone giving details also says whereabouts in the country they are?

I too am in cloudy Manchester. Well, Disley. 16*250W panels facing directly south, according to submitted meter readings (and assuming I’m understanding the properly) they produced 3300kWh in twelve months ending in March

If you have a shit tank with an undersized coil (ie not one designed with solar in mind) then an immersion in the same tank could operate better.

Can’t think of many other scenarios.

It’s on my list of things to do to fit a solar thermal on the dormer roof….. But that’ll be when the boiler dies (grant combi @12years old so far…… Be replaced with a system boiler and tank with solar thermal input)

Just been up to look at my generation meter -showing 2780kWh for the 10 months (I didn’t have the data logger in the above posts from the start)

We have exported 800kWh

My PV to immersion boost provides me with more hw than thermal panels ever did.

My hot water is heated to a higher temperature with the PV than by the boiler.
This is because the thermostat on the immersion is set to to the maximum.
It therefore actually gives more usable hot water when it’s diluted to the required temperature.

Can I kindly request that anyone giving details also says whereabouts in the country they are?

The chart that I posted earlier was from our place in North Wales.
(And we all know that West is best 😉)

@Greybeard
Thanks for the info. I need to investigate further 👍

Not much different to keeping a boiler topped up.

Tried refilling solar thermal panels with glycol? Slightly different than adding water to a gas fired boiler system. Not to say it’s impossible, but get it wrong and you’ve a right mess on your hands. Given location I would say not a job for the untrained!

I am surprised at that they are definitely not complicated. If a heating engineer can’t understand a solar thermal solution they are not a heating engineer!

Just my experience. 9/10 heating engineers just aren’t interested/never return calls. Service costs roughly in the region of £150/year. I’d be amazed if the benefit/saving even covered the servicing costs.
In my case the solar thermal was inherited as part of the local authority’s energy saving requirements for new builds (albeit 6 years ago) which could well explain…

Must have been something wrong because the effectiveness of solar thermal much higher.

Quite possibly, the contractor at the time didn’t know their arse from their elbow. But, a 2 panel thermal system was producing hw up to 40ish degrees from April-Oct, then hardly anything after winter when the system lost its efficiency (glycol evaporated apparently!)but the quantity just wasn’t good enough for more than 1 shower. The hw had to be on at the boiler all the time. OTOH my immersion boost kicks in around 700W from the inverter, and for a family of 4 I’ve only had to turn the gas boiler (hw) on for 2 weeks. (End Feb install).

Hello all – new to this solar game, new build house with 4.2kw installed in the roof.
I’m wondering what everyone else uses to monitor their domestic consumption – I’ve got a Wi-Fi dongle feeding data from the inverter, (Solis S5), plus various apps showing smart meter data, but have been eyeing up systems that will let me see both in ‘real-time’ ie efenergy pro.
https://uk.efergy.com/efergy-pro/

Any advice or experience to share?
Thanks!

90 quid !

I’d consider it if it didn’t use your smart phone as the output.

If someone does a smart meter type display that sat in your kitchen that showed generation and usage instantaneous – would save hauling phone out for a look before putting a high drain item on.

but have been eyeing up systems that will let me see both in ‘real-time’ ie efenergy pro.

That system presumes that there’s a separate cable running from the inverter to the consumer unit.
I would imagine many don’t (neither of my two do).

That Efergy Pro looks like it has a lot of gadget for your money. I have a Zappi EV charger which detects export and can be set up to make best use of it for charging the car, it has a real time graph showing the export but I don’t think the data is saved long term. My inverter is a Sunny Boy and I can download generation data (watts, recorded every 5 min).

Some information on my installation.

A total of 15 x 250W panels, 9 on the house and 6 on the garage, facing SE on a 30º roof at 53.4ºNorth (Cheshire).

This is the total output by month since installation in 2011. It’s about 3000kWh/year.

The panels on the garage are shaded by trees across the road when the sun is low, which reduces their output during winter – but even the ones on the house that are not shaded produce very little at that time, so in practical terms it doesn’t make much difference.

Tried refilling solar thermal panels with glycol

Yeah, built my own charging system with a old shower pump and a plant sprayer, washing machine tails. Not complicated.

I designed my solar thermal after a German friend related all the niggles with his.

The pump was unreliable and expensive to fix – I worked out that if I put the panel on the bottom of the roof and the tank in the top it would thermosyhon so wouldn’t need a pump. I used 18mm pipe throughout to improve flow.

He had had problems with the control system sometimes pumping when it shoudn’t or visa versa so sometimes the tank was heating the panel – with thermosyphon there is no control system.

Today is cloudy, yesterday was warm with bright sun from 15h. I’ve just measured the water temperature, 47°C.

I use car anti-freeze and just top up the washing up liquid bottle I use as a header tank once a year.

It’s a shame the UK smart meters don’t have a P1 port (like the european ones do) – data could then be extracted.

My system PV is 15x250W panels on SSE facing roof, no obstructions, near York.
Last 12 months output 3750 kWh, with 2260kWh used for hot water (Solar iboost controller).
The 300 litre unvented tank, as someone else above mentioned, has the immersion thermostats set near max, probably about 80C. Blending valve on tank outlet drops temp to ~52C for use.
We need about 6-8kWh into hot water to cover daily usage (2 long showers and 1 bath), the tank can hold about 25kWh of heat energy when maxed out.
No fancy logging other than sad geek here takes meter readings every week and pops into a spreadsheet.
If I was installing a new system today, I’d seriously consider ~8kW of panels, similar HW system, but also battery storage. At the moment we’re importing about 5kWh per day of electric, a fair portion of that is evening cooking (all electric), PV system output is dropping quite rapidly by 5-6pm.
We moved dishwasher use to mid-mornings rather than 8pm, which seems to have saved a 1-2 kWh per day import. Also wifey has learnt to use delay start on the washing machine, so doesn’t run before 9am, and try to do the washing on sunny days.

random question – we’re having a bunch of work including probably a new roof done late this year or early next. Are there cost savings of having solar done at the same time (I’d guess they don’t have to do scaffolding etc?)

Yeah, the only real saving is scaffolding unless it’s an in-roof install.

Regarding batteries – I have the option of 5, 10, 13 16 and possibly 20kWh of storage at various price points.

Our average daily usage is less than 20kWh, I’m angling toward either the 10 or 12kw packs given our 5.5kw array and usage. This would allow us to charge the battery through the day and use it in the evening in summer and to partially charge from the grid in the evenings on an off peak tariff for the winter months.

Does this sound right or should I scale up/down?

@steveb

Also near York, they turn up tomorrow to fit a couple of EV chargers, and in three week to fit 7.3kW of PV plus the immersion system for the hot water tank.

The 13kWh / 5kW battery is on order, but that will be 11 months still due to lead times – however it will give me fault ride through when the mains goes off. I work for the local DNO, and strangely all of us hav e wood burners, Honda generators or these days solar and batteries. It’s almost like we know however good the electricity is, it’s never going to be perfect.

Connection agreement with the local DNO for up to 8kW export.

I think I roughly followed your advice.

@Daffy I reckoned 13kWh as a day and a bit of present usage made sense for me.  Even with car charging, given the PV is running during the day you should be able to survive a mains fault in reasonable comfort. Get fault ride through though for that worthwhile feature.
If you’re not going to be car charging, then smaller is fine, as classic domestic usage is day and evening. PV covers the day, the battery mainly covers the evening with s bit left over for the night.
How much smaller depends on your standing load.

…it will give me fault ride through when the mains goes off. I work for the local DNO…

Things are bad when you work for the DNO but can’t stop the mains going off!  Seriously, though, I guess you must have your battery on the AC side of the PV inverter, with its own transformer and inverter. How does that compare with the battery on the DC side?

We have 4 x 250w panels on a new build. Probably powers the lamp in the living room for 2 months a year. Still, better than nothing!

@igm
Ironically 2/3 of the village had a few hours outage a couple of weeks ago. Village FB group had a photo of very dead squirrel on the transformer. The 20 or so houses at this end of village have a separate pole mounted transformer, so we were ok.
Also have the obligatory stw wood burner. Harvested another trailer load of ash last weekend, currently splitting a few barrow loads per night as after work wind down.

Things are bad when you work for the DNO but can’t stop the mains going off!  Seriously, though, I guess you must have your battery on the AC side of the PV inverter, with its own transformer and inverter. How does that compare with the battery on the DC side?

The joke comment is still serious. Our entire job is about where the electricity isn’t working or isn’t at all. We rarely go where it is working properly. That probably colours our views a bit. Added to which, in the storms or floods we end up pretty much abandoning our families for days, or with Arwen weeks. It’s nice to know they’re ok, which again colours your thinking.

And with decarbonisation the need for multiple resilient energy vectors into the home will increase. Ask anyone who does reliability studies for a living.

On the AC or DC question, I like the idea of a single bidirectional inverter and EV charging, PV, battery and maybe lightning circuits (possibly heating controls) coming off the DC side. Potentially more efficient, certainly higher speed EV charging.
However as a home owner, I’m using readily commercially available components from trusted local contractors so they’re AC connected today.  But could the panels and the battery be reorganised with different power electronics in the future? Possibly.

Does anybody have a MyEnergy Eddie? Had a quote that included one of these..

I like the idea of a single bidirectional inverter and EV charging, PV, battery and maybe lightning circuits (possibly heating controls) coming off the DC side.

Thanks, that would be more efficient. I was thinking particularly of coping with a mains fault. Our inverter, and I assume all other grid connected ones, isolates itself on loss of mains so anything on the DC is no use as fault cover.

A slight diversion to the conversation – apologies but I really feel I should share this with people as it’s shaken me a bit…..

After fitting Solar Thermal (see entries previous in the thread) I’ve been keeping an eye on my smart meter and couldn’t figure out what was using 11kWh of gas a day. The meter reported this usage despite the sunny weather and no cooking. What the hell is using it?

The pilot lights (I have two – one for a hot water boiler and one for heating).

I checked the smart meter half-hourly readings and sure enough, every half an hour day in, day out, 365 days a year I use 0.022m3 of gas. Over 24hrs that’s 1.056m3 (or 11 kWh). Over a year it’s 385m3 or 4066kWh!

That’s 27% of our gas usage.

Blimey.

They are both off now during this sunny spell, but I’ve lived with the system running like this for 22 years. That hurts my brain as I thought I was pretty efficient with our use of the system. I would always have put this level of daily use down to heating water previously…….

@Greybeard

All G83 / G98 inverters switch off on loss of the incoming 230V mains.

The Tesla Powerwall is not G98 compliant so you have to apply under G99 not inform under G98, but it has the circuitry to maintain the AC in the house.  A contactor disconnects the house from the mains rather than the inverter from the house.

Other G99 batteries may be available. Not sure.

We’ve been looking at solar, and in truth I’ve got cold feet – interested to see what the group view is.

No contractor we’ve had yet will warranty their work beyond one year. I’m nervous. – as I perceive it to be moderately serious work to the roof with the potential for errors/leaks/bad workmanship impacting further down the line. I’d hoped/expected contractors to offer maybe 5 year warranties.

Any views? Have I just had bad contractors or is this fairly normal and I’m a nervous Nellie?

Thanks!

My installer will warranty the equipment for 10 years including the inverter…whether they’ll still be in business in 10 years…

Sorry – my point is around the install, not the equipment. The manufacturer warranties the equipment, it’s the warranty offered on the install I’m worried about.

If you are thinking of having solar panels installed, I strongly recomend having wire mesh put around them to prevent birds nesting underneath. It’s cheaper to have this done when they’re installed and the scafolding is in place as opposed to later on when access is harder. Pigeons just love to nest under the panels, filling your gutters with old nests, crapping all over the place and making a din…. (speaks from bitter experience)

im in aberdeen….. people keep telling me solar doesnt work here – isnt viable here …..

the numbers speak for them selves and im trying to get a battery currently….

@igm, thanks, that’s useful information.

@northernremedy, a limited warranty doesn’t remove your statutory rights. Warranty may (or may not) give you something better than statutory and possibly an easier way to claim.

Our panel installer was recommended by a colleague and did a brilliant job, no problems so far in 12 years. They went out of business a year after our installation, so any extra warranty would have been worthless.

Anyone used the “solartogether” service offered by local councils by getting bulk purchase power to supposedly lower costs? Or is it the usual shitshow of over priced dodgy installers..

Also, any views on house values with or without solar, especially since elec prices went up, as we are hoping to move at some point in the next 5 to 10yrs

How much are people paying for their batteries?