New houses with PV

yannakis

Hi guys, most of the newbuilds come with PV installed on the roof. Some builders install panels for hot water only, but most install PV.

All real estate agents I've met on open viewings know nothing beyond the acronym and probably the actual shape. One opened the leaflet to say that they are.. pho-to-vol-taics! Anyway, so I gave up asking them questions :pac:

Generally, what happens with surplus electricity being produced? From what I read around boards today, I understand that electricity companies no loger pay for exporting electricity back to the grid..

Would the installation of a battery like Tesla Powerwall be a good investment to theoretically capture surplus electricity while away (at work), and use it when at home in the evening?

Tefral

Most of the PV panels are a joke and are only there to satisfy the BER cert and Part L of the building regulations.

yannakis

Tefral wrote: »

Most of the PV panels are a joke and are only there to satisfy the BER cert and Part L of the building regulations.

Do you mean they are more.. decorative rather than productive? :rolleyes:

Dudda

Batteries are very expensive. If you divert the additional energy to heat the hot water it's the best use of excess at the moment as otherwise it goes back to the grid but you don't get any feed in tariff. Everyone needs hot water all year round.

yannakis

How expensive are you talking about?

antoinolachtnai

yannakis wrote: »

How expensive are you talking about?

Well here's one, just for an example.

https://www.ecopowersupplies.com/samsung-sdi-3600wh-solar-energy-storage-battery-solutions

CIARAN_BOYLE

yannakis wrote: »

How expensive are you talking about?

I agree with the idea that hot water is your best battery.

If you consistently find yourself with more hot water than you need then you can look at a battery but I would imagine that you won't need it unless your house comes with a lot of panels.

yannakis

Thanks for the input guys!

I was thinking of a model where:

• electricity from PV is stored in the battery
• house only uses electricity from the battery until it reaches it's limit down
• only when the battery is full, re-route the surplus to the immersions for hot water
• battery capacity could then cover usage after sunset (pretty sure this is not a term )
• extra hot water on demand from the backup (which is mostly gas)

My apologies if I'm describing something very basic, but I'm only now getting introduced to this world :pac: If we exclude the battery cost (similarly to how I exclude the house purchase price for example), would it make sense?

I guess to have a complete image, we need know what kind of PVs the developer will install.

antoinolachtnai

If you exclude the capital cost of the battery it makes perfect sense. But the problem is that you are incurring a big up front capital cost for something that you can buy from the grid for a very low ongoing cost. 6000 euros will buy 30 or 40 thousand kWh of electricity.

yannakis

What you're saying makes sense, but I'm trying to find alternatives to the 2 elements that make me mad (from the out-of-the box setup the developers are offering). Surplus being fed to the grid for free, and pointless amounts of hot water

KCross

yannakis wrote: »

What you're saying makes sense, but I'm trying to find alternatives to the 2 elements that make me mad (from the out-of-the box setup the developers are offering). Surplus being fed to the grid for free, and pointless amounts of hot water

You need one of two things, imo:

- A Feed In Tariff to take your excess
- A battery to soak up the excess

The Feed In Tariff doest exist for new entrants in this country. Hopefully that will change in the near future and then you have an infinite battery in the grid.

The backup battery idea is just too expensive right now(see Tesla Powerwall). The cost of those will drop but as pointed out the €6k just doesnt justify itself at the moment.

If FiT comes in the backup battery wont be required.

antoinolachtnai

The only way there can be any sort of significantly feed in tariff is with a subsidy. The reason is that PV electricity has very low value. It never produces at times of high demand and it is not predictable.

there are also serious practical issues, i.e. Metering arrangements.

KCross

antoinolachtnai wrote: »

The only way there can be any sort of significantly feed in tariff is with a subsidy. The reason is that PV electricity has very low value. It never produces at times of high demand and it is not predictable.

True. However, other countries have it, no reason why we shouldnt. With smart grid technology you can deal with the unpredictability.

antoinolachtnai wrote: »

there are also serious practical issues, i.e. Metering arrangements.

Why is that a serious issue? You get an import/export meter and thats it. Hardly a serious practical issue?

antoinolachtnai

You can cope with the unpredictability, certainly, by adding alternative dispatchable capacity. This is no small thing to do however. It means that in addition to subsidising the FIT, you also have to build or retain other capacity. The double cost makes it expensive.

Other grids are larger or have extensive interconnection which makes it easier. They also have less wind.

It can certainly be done. It will not be cheap or free.

Re meters, there are certainly practical barriers. First, the current meter that is used is very expensive for domestic use. Second if you do get one, it won't feed into electricity settlement unless you are registered as a commercial customer. System changes are needed. The good news is that the Winter Package is likely to mandate smart meters for those who want them from 2020.

KCross

antoinolachtnai wrote: »

You can cope with the unpredictability, certainly, by adding alternative dispatchable capacity. This is no small thing to do however. It means that in addition to subsidising the FIT, you also have to build or retain other capacity. The double cost makes it expensive.

Other grids are larger or have extensive interconnection which makes it easier. They also have less wind.

It can certainly be done. It will not be cheap or free.

Dont our interconnectors give us the flexibility we need?

I'm not an expert and wont argue the point with you but I thought that the modern plants could be spun up and down relatively quickly.

Do other countries that have FiT require a government subsidy? What form or level of subsidy is required in UK, for example? Do you know?

antoinolachtnai wrote: »

Re meters, there are certainly practical barriers. First, the current meter that is used is very expensive for domestic use. Second if you do get one, it won't feed into electricity settlement unless you are registered as a commercial customer. System changes are needed. The good news is that the Winter Package is likely to mandate smart meters for those who want them from 2020.

ESB charge €350 for the meter, I believe. Probably because its not being bought in bulk. The meter cant be that much more expensive to produce than a day/night meter or a smart meter?

What is "electricity settlement"?
What system changes are needed? There are already import/export meters in the country. Presumably they work?

I'm not getting the "serious practical issue" you are referring to.

antoinolachtnai

€350 euros is a lot for sure, when the returns are so small in domestic solar to begin with. It could add a year or two to the payback period.

You can buy these units off the shelf, so quantity is not the biggest issue. However it is a three phase meter which makes it expensive I imagine.

Solar is massively subsidised in GB and elsewhere through the FiT. Electricity is around 4p/kWh, sometimes less in GB in daytime hours on the wholesale market. There is nothing wrong with subsidising per se, but there is a question to be asked about the most effective way of using subsidies would be.

Modern gas plants can be spun up quickly, sure but these types of plants are expensive to run. They are also expensive to build. Who is going to build or maintain them to run a few hundred hours a year? They will somehow need to be subsidised too.

Our interconnection is only a sixth or so of our total demand. And it is only with one other grid, because of our location. Most European grids are interconnected with a number of grids.

Settlement is the process by which suppliers are charged for electricity their customers consume and generators are paid for their generation. Your smart meter export data has to be taken into account in settlement for anyone to get paid for their feed-in.

The practical upshot is that changes are needed to systems. This takes time and costs a lot of money. It has not been done. How this could be done faster is a legitimate topic for discussion for sure. But for now metering is a big practical barrier.

rolion

My humile opinion...PVs on the new houses is a big step towards awareness and moderate / self consumption process / education.
It will "tease" other people in to looking,evaluating and maybe committing on to the ideea of renewables.

I guess those panels have 250W and with local or build-in inverters can generate around 500-700KwH in a sunny day.
The owner then can do heavy hungry applciances during the peak PV generation time.

The issue with FiT,well when started my adventure on the solar motorway,i was based on it as a financial return towards my investment.
Then, after i did my home work and read / seen more i am more against it by day goes on !!
If a person wants to get PVs then do it as without the FIT backup,organise your consumption around the God Sun' "exposure".I've said already too many times, organise your "electrical life" around it...

BadDay:



BetterDay:



To all above,happy harvesting (i do not own the expression)

Conor20

rolion wrote: »

My humile opinion...PVs on the new houses is a big step towards awareness and moderate / self consumption process / education... The owner then can do heavy hungry applciances during the peak PV generation time..If a person wants to get PVs then do it as without the FIT backup,organise your consumption around the God Sun' "exposure".I've said already too many times, organise your "electrical life" around it..

Agreed. OP - batteries will be cheap enough to make sense in 2-3 years given how fast their prices are falling, but there are good options right now that don't require them. Buy timer plugs from Lidl (or a programmable IFTTT plug) and run your appliances during the day when PV is available. Essentially, rather than storing the energy during the day to use for your demand in the evening, move your demand to the daytime. You can use a Solar iBoost or similar hot water diversion unit to send the excess PV energy into water. If you have an electric car (if you don't, you should consider getting a cheap second hand Leaf in the UK), you could order a charger like this one which will put any excess PV straight into your car while it's home. We installed a 2.2kW PV array 4 months ago and it's been surprisingly easy to change our habits to maximize our use of the PV generation.

JohnnyB23

Hi Conor20,
I'd love to hear more about your PV installation, i.e. cost of PV bundle and installation, effect on electric bills. I'd really appreciate a PM with suppliers details.

yannakis

Thanks @Conor20, the idea of the Solar iBoost looks interesting! I'll look into it more to understand how it operates.

In regards to the timer/IFTTT plugs, on what devices do you use them? I believe the only energy hungry devices that can operate without our presence (besides the hot water boiler) are Dishwasher, Washing machine, and Drier which will have their own built in timers anyway.

rolion

Keep the busines local rather than across the sea...
Bought it from HERE .

Keep in mind that your 300L cylinder will need a huge amount of energy to be efficient.
What we do with a small PV install is just warm-up the bottom of the cylinder with few degrees.

quentingargan

The ultimate plan is to roll out smart meters for all householders, so I would hold on for a bit and see what form the incentives being considered by government come in, and whether they are made retrospective for existing installations.

I would be careful about products like Solar iBoost. The units using phase angle will distort the grid to your neighbours. I tested one of these and got a very bumpy sinewave at my neighbours house 300m away. There are slightly more expensive units that don't use phase angle and are harmless. There are three main technologies in water diversion units - phase angle, burst-fire and PWM. The latter is best. Burst fire may cause flicker of old-fashioned bulbs.

yannakis

@quentingargan Can you recommend any products that use Pulse-Width Modulation?

quentingargan

yannakis wrote: »

@quentingargan Can you recommend any products that use Pulse-Width Modulation?

PM sent

yannakis

I've got a slightly related question. The house is currently being build, and I'm wondering if it would be a good idea to make provisions for an electric car charge point. Not sure what's required for it as we don't have an electric car yet, but in the future we definitely will.

KCross

yannakis wrote: »

I've got a slightly related question. The house is currently being build, and I'm wondering if it would be a good idea to make provisions for an electric car charge point. Not sure what's required for it as we don't have an electric car yet, but in the future we definitely will.

All you need to do is get the electrician to run a cable from the consumer unit to the point in the outside wall where you would mount the charge point.

The cable should be at least 6sqmm. Nothing else required other than that cable. When you get the car you can simple wire both ends of it and you are good to go without having to chase walls etc.

You should also consider getting the upgraded ESB connection(16kVA) rather than the standard 12kVA.

yannakis

Thanks for the quick reply, the developer came back to us meanwhile with the electrician's contacts but noted this can only be performed after closing.

So I guess we'll leave it until we actually get an electric car. The "box" with the meters is outside, probably 1-2m from where the charge point would be installed but the consumer unit is nowhere near that from the inside - at least 10m away..

Is it messy to upgrade to 16kVA at a later stage?

KCross

yannakis wrote: »

Thanks for the quick reply, the developer came back to us meanwhile with the electrician's contacts but noted this can only be performed after closing.

So I guess we'll leave it until we actually get an electric car. The "box" with the meters is outside, probably 1-2m from where the charge point would be installed but the consumer unit is nowhere near that from the inside - at least 10m away..

Is it messy to upgrade to 16kVA at a later stage?

Dont settle for that from the developer. Its one cable which will cost maybe €50 at most and its MUCH easier to put it in at build time than to do it after when walls are plastered/painted etc. He will be running cables anyway to external lights etc so running one extra cable is nothing extra. Just clarify you just need the cable run not the charge point installed.

The upgrade to 16kVA isnt messy to do later. Its usually just a fuse swap out by ESB Networks BUT it costs more to do it later and it will require an electrician to certify that the house can take the extra current. Your new house will of course be fine but if you do it later you will still have to get a cert from an electrician at that point so that will add another few quid for that cert as no electrician will provide that for free.

Page 5 of this docs gives you the ESB Networks pricing.
https://www.esbnetworks.ie/docs/default-source/publications/esb-networks-dac-statement-of-charges.pdf?sfvrsn=16

It will cost you an extra €700 now or €1169 later. Its a once off charge for ESB Networks. Add on the electricians cert if you are doing it as an upgrade later.

What are you planning on using for heating? If its a heat pump and/or you have an electric shower its better to get the upgraded supply.

yannakis

Thanks @KCross, I will speak with the electrician and see how this goes..

Heating will be gas, and hot water is connected to (surplus) solar electricity, and the gas boiler for backup.

KCross

yannakis wrote: »

Thanks @KCross, I will speak with the electrician and see how this goes..

Heating will be gas, and hot water is connected to (surplus) solar electricity, and the gas boiler for backup.

You probably dont need upgraded connection then.

Tell electrician the chargepoint would draw 32A for 4hrs(thats worst case scenario) and he can advise whether you need the upgraded connection then or not based on the rest of your house setup.

yannakis

Thanks for your help and all the clarifications. I was suspecting I was only seeing the tip of the iceberg :pac: :pac:

yannakis

Question about the 16kVA - besides the higher initial cost, is there a difference in the standing charges?

KCross

yannakis wrote: »

Question about the 16kVA - besides the higher initial cost, is there a difference in the standing charges?

No, same as standard connection.

Your electricity provider (Energia, Airtricity etc) wont even know/care you have a 16kVA connection. Having it just allows you to draw more power so that is good news for them... the more you draw the more you pay!

championc

Does anyone have a live link to data from a Solar PV system. We all know the potential during blue sky days but I am interested in the output of say a 2kw array when we have a normal cloudy day

quentingargan

Mine is HERE. Old system with 1.8kw of poly modules facing south at 40 degree slope and running through a 1.5kw inverter in Bantry. Often quite cloudy here as we are on the side of a hill...

championc

Real data is king. People can make all sorts of promises but data never lies.

What is your estimate on the number of years for it to pay for itself ?

quentingargan

championc wrote: »

What is your estimate on the number of years for it to pay for itself ?

Considering I put this in a few years ago when panels were €2.50 a watt, the payback is in decades rather than years. But if I put in a 1.5kw system at today's prices, giving me this sort of yield it would be OK. I work from home so use at least 1/2 of the electricity produced. I get paid 9c for exporting the other half, but even if I used a diversion device to send that to the immersion, it would still save me 9c. I reckon on an average saving of 13c for electricity produced, it would pay back in about 10 or 11 years at today's hardware prices

championc

Is there any rumblings about the return of a FiT ?

I remember the figure of about $1 per Watt was always mentioned as being the required level to be economically viable. Are we hitting this level yet ?

unkel

quentingargan wrote: »

Considering I put this in a few years ago when panels were €2.50 a watt, the payback is in decades rather than years. But if I put in a 1.5kw system at today's prices, giving me this sort of yield it would be OK. I work from home so use at least 1/2 of the electricity produced. I get paid 9c for exporting the other half, but even if I used a diversion device to send that to the immersion, it would still save me 9c. I reckon on an average saving of 13c for electricity produced, it would pay back in about 10 or 11 years at today's hardware prices

Quentin, are those figures based on you installing it yourself or on what you'd pay for it be installed by an installer? If it is the latter, I'm very interested in a PV install, if that would have a pay back time of around 10 years, without a decent FIT being there. It might arrive at some time in future after all

Have a 100% south facing roof and based in Dublin. I already have a Kingspan 40 tube system for heating water. Have you any rough figures of what a complete install would cost (hardware and fitting all included), and what system size recommended by yourself for a 145m2 semi-d house for a family of 5, what the expected annual kWh production of the panels is split by month and time of day?

quentingargan

unkel wrote: »

Quentin, are those figures based on you installing it yourself or on what you'd pay for it be installed by an installer? If it is the latter, I'm very interested in a PV install, if that would have a pay back time of around 10 years, without a decent FIT being there. It might arrive at some time in future after all

Have a 100% south facing roof and based in Dublin. I already have a Kingspan 40 tube system for heating water. Have you any rough figures of what a complete install would cost (hardware and fitting all included), and what system size recommended by yourself for a 145m2 semi-d house for a family of 5, what the expected annual kWh production of the panels is split by month and time of day?

If you already have solar hot water, without some sort of feed in tariff for your exported surplus power, PV will not be viable.

Mine was a self-install. The thread here was originally about a new build and many of these are putting in small systems to meet Part L, whereas a larger system would not cost all that much more, but the builder is simply looking for the lowest cost system that ticks the boxes on Part L. If you are building a house and the scaffolding is in place, it is viable to include PV and use your surplus power to heat water. If you are already sticking in 3 or 4 panels for Part L, it makes sense to put in 8 or 10 instead. But at the moment, retrofitting onto an existing house, especially where there is already solar water heating, does't make financial sense.

Effects

Dudda wrote: »

If you divert the additional energy to heat the hot water it's the best use of excess at the moment.

What's the simple payback on the diverter? Our engineer said it wasn't worth it and to wait for a feed in tariff that will be coming down the line.

quentingargan

Effects wrote: »

What's the simple payback on the diverter? Our engineer said it wasn't worth it and to wait for a feed in tariff that will be coming down the line.

I think a diverter is only worth looking at if you have six or more panels. With 3 panels, for example, your system will generate about 600kwhrs per year. You will probably use at least 1/3rd of this, but usually half. So you can send 300 to 400kwhrs to the immersion. You can do this on night rate or heat water from oil or gas for about 9c so the potential saving is about 300 to 400x9c or €27 to €36 per year. So unless you are feeling really bloody minded about not giving electricity to the grid for free, I would leave well enough alone

On the other hand, if you have six or eight panels, a diversion system will produce a similar amount of hot water as a standard 4 sqm flatplate system

metricspaces

quentingargan wrote: »

I think a diverter is only worth looking at if you have six or more panels. With 3 panels, for example, your system will generate about 600kwhrs per year. You will probably use at least 1/3rd of this, but usually half.

So the average semi-d that has 4 panels to comply with Part L of building regulations would generate 800kwhrs a year.

I guess this is based on the assumption the panels are on a south facing roof?

Is the 800kwhrs the actual consumable amount? Or would there be loses in the system e.g. you only get to consume 90% of it?

Based on Airtricity rates of 17.76 per kwhr, your average semi-d is saving a theoretical max of 142 euro a year?

Unless you are at home during peak sunlight hours to consume this 800kwhrs, then is it most likely a large percentage will go back to the grid for free? Of course you could schedule applicances to be active during this period.

How much does is cost to install these 4 panel setups being used to comply with Part L of regulations? I'm wondering what the actual saving is here and the payback.

Obviously the saving depends on your electricity usuage profile. If we take worst case example of nobody in the house 8am to 6pm Mon to Fri, with typical appliances etc. Then best case being you use up all the 800kwhr generated.

On the face of it, these 4 panel systems seem more like an effort purely for optics.

antoinolachtnai

Well the reason it is in the regulations is because there isn't a payback on it. There are a variety of 'social' goods being served.

Just because electricity spills back onto the grid does not mean it is lost. The benefit of this power is shared by all electricity users and small users all over the country benefit from a (small) reduction in electricity bills as a result.

metricspaces

antoinolachtnai wrote: »

Well the reason it is in the regulations is because there isn't a payback on it. There are a variety of 'social' goods being served.

Just because electricity spills back onto the grid does not mean it is lost. The benefit of this power is shared by all electricity users and small users all over the country benefit from a (small) reduction in electricity bills as a result.

I see there's a benefit for energy companies getting free electricity. I'm focusing here on the benefit to the consumer who buys a house with a 4 panel PV system.

quentingargan

metricspaces wrote: »

So the average semi-d that has 4 panels to comply with Part L of building regulations would generate 800kwhrs a year.

I guess this is based on the assumption the panels are on a south facing roof?

Is the 800kwhrs the actual consumable amount? Or would there be loses in the system e.g. you only get to consume 90% of it?

Based on Airtricity rates of 17.76 per kwhr, your average semi-d is saving a theoretical max of 142 euro a year?

Unless you are at home during peak sunlight hours to consume this 800kwhrs, then is it most likely a large percentage will go back to the grid for free? Of course you could schedule applicances to be active during this period.

How much does is cost to install these 4 panel setups being used to comply with Part L of regulations? I'm wondering what the actual saving is here and the payback.

Obviously the saving depends on your electricity usuage profile. If we take worst case example of nobody in the house 8am to 6pm Mon to Fri, with typical appliances etc. Then best case being you use up all the 800kwhr generated.

On the face of it, these 4 panel systems seem more like an effort purely for optics.

You are quite spot on. Except that the panels are more than optics. They bring the house's carbon emissions and energy profile down to an acceptable level. The hardware and installation cost for these 4 panel systems in bulk is typically about €1300 to €1400 for a housing estate. Most houses seem to consume between 1/3 and 1/2 of the power depending on timing of appliances and especially if someone is at home during the day.

The production is dependent on orientation, but with very little difference between SE and S. The figure is what is delivered. In fact often it is a bit better than this amount - the DEAP calculations are quite conservative.

antoinolachtnai

metricspaces wrote: »

I see there's a benefit for energy companies getting free electricity. I'm focusing here on the benefit to the consumer who buys a house with a 4 panel PV system.

The benefit is that the consumer gets to buy the house. You cannot buy a house that doesn't have some carbon-reducing measures. It is a regulation, intended to deliver long-term benefit to the community, not to the individual householder.

Reduced carbon emissions is one such community benefit.

If the price of electricity were to go a lot higher then there would be a bigger benefit for the householder, certainly. But it is really not about individual benefit to the individual householder.

The same goes for most of the building requirements. Fire safety measures similiarly mainly benefit the community by avoiding house fires and the social and economic consequences they bring by damaging multiple houses. Similarly, insulation measures are probably not really worth the extra time and trouble given the low cost of fossil fuels, but they reduce dependence on these fuels which bring a lot of benefits.

Another benefit is that it increases the skill level and the scale of installations, which increases uptake in the long-term.

So you can't just look at in terms of the cost-benefit analysis for a single user.

metricspaces

antoinolachtnai wrote: »

So you can't just look at in terms of the cost-benefit analysis for a single user.

I would imagine it is how any home buyer is going to look at it. A builder is not putting this system in for free, the end result is the house price will increase by at least the cost to install the system.

You can analyse a situation from many perspectives; it does not make that analysis incorrect or irrelevant simply because it does not align with another's perspective.

Assume a 4 panel system, producing 800kwhr a year, with installation cost of 1400e.

• Use 33% of electricity produced. Gives a 46e a year saving. Pay back of 30 years.
• Use 50% of electricity produced. Gives a 70e a year saving. Pay back of 20 years.

With an average 3 bed house having an electricity bill of approx 1211e a year, this leaves the consumer with a saving of between 3.8% and 5.8% on their bill each year.

Does it make economic sense to try and harness 100% of the electricity produced? I see you can get an Solar iBoost+ from Amazon for 380e. Say 500e shipped and installed?

Let's assume you can harness 100% of the electricity through using an iBoost (is this even remotely realistic?)

• Currently using 33% of electricity produced before iBoost installed. Gives a 94e a year extra to save. Pay back of 5.3 years on the iBoost.
• Currently using 50% of electricity produced before iBoost installed. Gives a 70e a year extra to save. Pay back of 7.1 years on the iBoost

The iBoost seems like a good investment for house buyers who got these PV panels "for free" by buying the house and where they are not set up to heat the hot water?

Is it possible to analyse the usage of these systems? This would seem like the most sensible thing to do - analyse usage for a year, determine how much extra could be harnessed via use of iBoost, then see if the pay back is worth it.

antoinolachtnai

As I understand it, it doesn't mean matter if the prospective purchasers wants it or not, the house has to have some part L measures to comply with the building regulations. The matter of return on investment doesn't really arise. That is not to say it doesn't matter, it's just that it doesn't arise as an issue for individual purchasers.

You also have to take a long term view. If an economic crisis were to drive the price of electricity up, the measures would suddenly be more financially attractive. A Feed in tariff, even a low one would also make it that bit more attractive. On the other hand a sudden glut of commercial scale solar on the electricity wholesale market, combined with time of use billing would make it less attractive.

metricspaces

As I mentioned, I am looking at this from the consumers perspective based on the facts as they stand right now. What may or may not happen in the future who knows. When the facts change, we can change the analysis.

So back to the topic. For people who have bought a house with a 4 panel PV system that is not heating the water, does it make economic sense to install an iBoost?

Assuming 800kwhr a year, between 400 and 533 kwhr produced by the PV panels is returned to the grid for free (based on quentingargan figures), what would this figure be if you installed an iBoost?

I know there will be variables involved - like how much hot water you use on a daily basis. But just trying to get a feel for how economically viable installing an iBoost would be. Has anyone any real world figures?

Is there some (cheap) mechanism to monitor how much electricity from the PV panels is being consumed and how much is being returned to the grid over a year? Do the electricity providers display how much is being returned to the grid on your bill even though there is no feed in tariff?

quentingargan

The Solar iBoost is one of the cheaper immersion divert devices. It works as a dimmer switch on phase angle, switching on the load at some point during the sine wave, and off at the zero crossing.

I've tried some of these devices and looked at the grid on an oscilloscope at my neighbours and it was severely distorted. I should imagine it could cause interference on some devices.

Ecologically, it also makes more sense to export surplus power during the day and heat your water using off-peak electricity at night. The proper solution is to get paid for your exports at a rate that makes this worthwhile. It is only in the absence of such a scheme that people are paying for this workaround.

Aren't we all supposed to have smart meters soon? They could easily handle the admin of paying for surplus power exported.