Help! I don't understand PV!

Silver Breeze · 29-03-2019 6:59pm #1

As the thread title says...I am not au fait with PV or electrics or theory, I'm a retired photographer who needs help in understanding what (if anything) I need.

The house: a 1950 bungalow, completely refurbished in 2014, much insulation, triple glazing, floor and attic insulation, evacuated tubes for solar water heating, big 300 litre immersion tank heated by electric coil (never used), gas worm (Oct - Apr only) and solar which is very effective. The house has two showers, kitchen sink. Gas condenser boiler driving radiators, not needed or used in summer months.

A lights are LED, some table lamps are on a 5 watt (is that right? Small round three pin plugs) circuit.
Kitchen has electric induction hob, electric double oven, microwave, fridge freezer, clothes washer, dishwasher, all purchased new in Dec 2014. Upon completion of works the house received a B1 BER rating.

Two people live in the house, both retired, both quite active, use tv, two computers, decent stereo system, read a lot.

I understand that to be eligible for SEAI grant for PV installation, up to x% of roof space may be used for panels. However, our bungalow has a four sided pitched roof and the single side suitable for all day sun is filled up with evacuated tubes, which work really well.

In addition, we have sizeable detached garage, with a single pitch sloping roof facing 200 degrees which would be ideal for panels. The garage has an internal fuse box driving three flourescent lights and four sockets for tools.
An armoured cable goes from the garage, undergound to the house, then internally to its own rcd in the fuse box, then to the esb meter outside.

Electric Ireland bills state on 5 Dec last:
"Your consumption is 406 kWh for this period compared with 757 kWh for the same period last year."

On 19 Oct last:
"Your consumption is 607 kWh for this period compared with 533 kWh for the same period last year."

This is getting a bit long winded, so I'll ask these questions:

Is that amount of kWh usage large or small?
Do we need to install PV?
Will we realise any savings after installation?

Thanks in advance for your help,
--Bob

Calahonda52 · 29-03-2019 7:20pm

What is the driving force here:
The grant?

Silver Breeze · 29-03-2019 7:23pm

Do the right thing, help the environment, get the grant...

Don't understand whether it is worth it...

wexfordman2 · 29-03-2019 7:56pm

Silver Breeze wrote: »

As the thread title says...I am not au fait with PV or electrics or theory, I'm a retired photographer who needs help in understanding what (if anything) I need.

The house: a 1950 bungalow, completely refurbished in 2014, much insulation, triple glazing, floor and attic insulation, evacuated tubes for solar water heating, big 300 litre immersion tank heated by electric coil (never used), gas worm (Oct - Apr only) and solar which is very effective. The house has two showers, kitchen sink. Gas condenser boiler driving radiators, not needed or used in summer months.

A lights are LED, some table lamps are on a 5 watt (is that right? Small round three pin plugs) circuit.
Kitchen has electric induction hob, electric double oven, microwave, fridge freezer, clothes washer, dishwasher, all purchased new in Dec 2014. Upon completion of works the house received a B1 BER rating.

Two people live in the house, both retired, both quite active, use tv, two computers, decent stereo system, read a lot.

I understand that to be eligible for SEAI grant for PV installation, up to x% of roof space may be used for panels. However, our bungalow has a four sided pitched roof and the single side suitable for all day sun is filled up with evacuated tubes, which work really well.

In addition, we have sizeable detached garage, with a single pitch sloping roof facing 200 degrees which would be ideal for panels. The garage has an internal fuse box driving three flourescent lights and four sockets for tools.
An armoured cable goes from the garage, undergound to the house, then internally to its own rcd in the fuse box, then to the esb meter outside.

Electric Ireland bills state on 5 Dec last:
"Your consumption is 406 kWh for this period compared with 757 kWh for the same period last year."

On 19 Oct last:
"Your consumption is 607 kWh for this period compared with 533 kWh for the same period last year."

This is getting a bit long winded, so I'll ask these questions:

Is that amount of kWh usage large or small?
Do we need to install PV?
Will we realise any savings after installation?

Thanks in advance for your help,
--Bob

As far as I am aware, the roof space has nothing to do with the grant. The roof space limitation is strictly whether or not you need to apply for planning permission for solar pv panels or not, and is unrelated to the grant.

Silver Breeze · 29-03-2019 8:00pm

Wexfordman...thanks, I am trying to establish if the roof sqm of the detached garage can be add to the roof sqm of the house, thus negaing the need for planning permission. SEAI says "we don't know..."

Gumbo · 30-03-2019 11:30am

Silver Breeze wrote: »

Wexfordman...thanks, I am trying to establish if the roof sqm of the detached garage can be add to the roof sqm of the house, thus negaing the need for planning permission. SEAI says "we don't know..."

The planning exemption covers the total squad footage of the full array within the site boundary.

So 6 on the roof and 6
On the shed will be the limit subject to the 50% rule being adhered to.

unkel · 30-03-2019 3:07pm

You are all forgetting the 12m2 maximum size of the solar install. Seeing the OP already has a 30 tube solar thermal system (based on his 300l cylinder), this area is largely taken up and there will be no more space for any PV.

Unless he either gets planning permission, or ignores the requirement for planning permission.

niallers1 · 01-04-2019 7:44pm

Silver Breeze wrote: »

As the thread title says...I am not au fait with PV or electrics or theory, I'm a retired photographer who needs help in understanding what (if anything) I need.

The house: a 1950 bungalow, completely refurbished in 2014, much insulation, triple glazing, floor and attic insulation, evacuated tubes for solar water heating, big 300 litre immersion tank heated by electric coil (never used), gas worm (Oct - Apr only) and solar which is very effective. The house has two showers, kitchen sink. Gas condenser boiler driving radiators, not needed or used in summer months.

A lights are LED, some table lamps are on a 5 watt (is that right? Small round three pin plugs) circuit.
Kitchen has electric induction hob, electric double oven, microwave, fridge freezer, clothes washer, dishwasher, all purchased new in Dec 2014. Upon completion of works the house received a B1 BER rating.

Two people live in the house, both retired, both quite active, use tv, two computers, decent stereo system, read a lot.

I understand that to be eligible for SEAI grant for PV installation, up to x% of roof space may be used for panels. However, our bungalow has a four sided pitched roof and the single side suitable for all day sun is filled up with evacuated tubes, which work really well.

In addition, we have sizeable detached garage, with a single pitch sloping roof facing 200 degrees which would be ideal for panels. The garage has an internal fuse box driving three flourescent lights and four sockets for tools.
An armoured cable goes from the garage, undergound to the house, then internally to its own rcd in the fuse box, then to the esb meter outside.

Electric Ireland bills state on 5 Dec last:
"Your consumption is 406 kWh for this period compared with 757 kWh for the same period last year."

On 19 Oct last:
"Your consumption is 607 kWh for this period compared with 533 kWh for the same period last year."

This is getting a bit long winded, so I'll ask these questions:

Is that amount of kWh usage large or small?
Do we need to install PV?
Will we realise any savings after installation?

Thanks in advance for your help,
--Bob

You probably have average electricity usage like I did before PV. I went for 4.2kw of solar PV and 4.8kwh of battery storage. With above solar system I expect to use less than 1400 kwh from the grid in a full year. I.e Less than €400 euro for the year.
We're just in April and have realised I now need a diverter as I'm exporting for free kwh to the grid as battery is filling up.

SEAI don't mind what size array you put up. They will pay the grant out as long as you follow their checklist. The planning rules around size needs to be brought up to date to take into account the solar PV grant.

I'm very happy with mine so I recommend PV.

KCross · 01-04-2019 9:12pm

niallers1 wrote: »

I expect to use less than 1400 kwh from the grid in a full year. I.e Less than €400 euro for the year.
We're just in April and have realised I now need a diverter as I'm exporting for free kwh to the grid as battery is filling up.

With your current usage that low you will never get the payback on a ~€500 diverter.

Let it go for free to the grid and do your best to maximise the daytime usage but dont spend more money that you'll never see back.

niallers1 · 01-04-2019 9:46pm

KCross wrote: »

With your current usage that low you will never get the payback on a ~€500 diverter.

Let it go for free to the grid and do your best to maximise the daytime usage but dont spend more money that you'll never see back.

You might have misread my last post.
It's what I'm giving away to the grid for free and what I pay to heat my water is what makes me want the diverter.
You can get a solar iboost for about 200 euro on ebay and it's very straight forward to install yourself.
I spend about 300 a year heating water so the payback should be there within a reasonable time frame or if not it's still a handy device to utilize most of your solar production.

uck51js9zml2yt · 01-04-2019 11:18pm

niallers1 wrote: »

You might have misread my last post.
It's what I'm giving away to the grid for free and what I pay to heat my water is what makes me want the diverter.
You can get a solar iboost for about 200 euro on ebay and it's very straight forward to install yourself.
I spend about 300 a year heating water so the payback should be there within a reasonable time frame or if not it's still a handy device to utilize most of your solar production.

Have you instructions on installation?

niallers1 · 01-04-2019 11:22pm

Fiona Stocky Yoga wrote: »

Have you instructions on installation?

You can go to the marlec (solar iboost manufacturer) website and download/ print off.

If you are comfortable wiring a plug you'll be able to wire a solar iboost.

KCross · 02-04-2019 10:51am

niallers1 wrote: »

You might have misread my last post.
It's what I'm giving away to the grid for free and what I pay to heat my water is what makes me want the diverter.
You can get a solar iboost for about 200 euro on ebay and it's very straight forward to install yourself.
I spend about 300 a year heating water so the payback should be there within a reasonable time frame or if not it's still a handy device to utilize most of your solar production.

This is the bit I dont understand then. You said you are spending €400 in total on electricity but you are saying you spend €300 on water alone.

How do you heat water today?

Generally speaking diverters are not worth the money. Heating water is cheap although you do seem to be spending alot on it so maybe your usage is higher than most somehow.

niallers1 · 02-04-2019 11:08am

KCross wrote: »

This is the bit I dont understand then. You said you are spending €400 in total on electricity but you are saying you spend €300 on water alone.

How do you heat water today?

Generally speaking diverters are not worth the money. Heating water is cheap although you do seem to be spending alot on it so maybe your usage is higher than most somehow.

The less than €400 is what I expect to spend now that I've installed Solar PV and Battery. Before the install I was using close to the national average.

My gas bill is high and I currently heat the water with Gas. There is three girls in the house so they seem to use a lot of hot water:)
As they get older I expect they will probably use more

I think the diverter will help to reduce my gas bill.

n97 mini · 02-04-2019 3:25pm

niallers1 wrote: »

The less than €400 is what I expect to spend now that I've installed Solar PV and Battery. Before the install I was using close to the national average.

My gas bill is high and I currently heat the water with Gas. There is three girls in the house so they seem to use a lot of hot water:)
As they get older I expect they will probably use more

I think the diverter will help to reduce my gas bill.

Are you heating the whole house at the same time? Almost a euro a day sounds like a lot. We have mains gas, zoned into 3 zones, one of which is the hot water. I worked out before it costs about 10c a day, which is roughly equivalent power consumption as leaving a 2kw immersion on for an hour. Tank is never stone cold, and water is only heated to about 42C.

niallers1 · 02-04-2019 3:40pm

n97 mini wrote: »

Are you heating the whole house at the same time? Almost a euro a day sounds like a lot. We have mains gas, zoned into 3 zones, one of which is the hot water. I worked out before it costs about 10c a day, which is roughly equivalent power consumption as leaving a 2kw immersion on for an hour. Tank is never stone cold, and water is only heated to about 42C.

I have mains gas too 3 zones. 42 Degrees is too low for your water tank

The tank should be heated to at least 60 degrees celcius at least once per week. Otherwise you will get legionella in your water tank.

unkel · 02-04-2019 3:42pm

niallers1 wrote: »

There is three girls in the house so they seem to use a lot of hot water:)
As they get older I expect they will probably use more

I think the diverter will help to reduce my gas bill.

If you're currently still exporting quite a lot (do you know how much?) and you can buy the hardware for EUR200 and self install, it might make sense

We're a family of 5 with my 3 daughters all in or coming into their teenage years, so we use massive amounts of hot water

We've got solar thermal (as well as PV), and that helps a lot with the hot water, even helps a bit in the middle of winter

n97 mini · 02-04-2019 6:53pm

niallers1 wrote: »

I have mains gas too 3 zones. 42 Degrees is too low for your water tank

The tank should be heated to at least 60 degrees celcius at least once per week. Otherwise you will get legionella in your water tank.

Once a fortnight it's heated to 65 on the immersion at night rate. But that doesn't impact on my gas bill, hence I didn't mention it.

Are you heating to 60 odd every day?

wexfordman2 · 03-04-2019 8:02pm

unkel wrote: »

If you're currently still exporting quite a lot (do you know how much?) and you can buy the hardware for EUR200 and self install, it might make sense

We're a family of 5 with my 3 daughters all in or coming into their teenage years, so we use massive amounts of hot water

We've got solar thermal (as well as PV), and that helps a lot with the hot water, even helps a bit in the middle of winter

Well, my 6kwp /5kwh battery system has been working great the last few days, the hot water diverted.got installed over the weekend.

So, I'm generating about 25kwh, exporting 5kwh, and importing 3kwh. The 3kwh import was night rate hours. My battery lasted till 11.25pm last night. And have immersion heated with that as well

Similar readings today so far.

unkel · 03-04-2019 8:48pm

The question to niallers1 is: how much were you exporting before you had the diverter and how much after the diverter was installed, per year?

In your case it probably makes sense as you have a very big array, so you will contribute a high number of kWh to heating your water. With the same cost of the diverter installed. For people with small or medium installs, they will lose money diverting to immersion.

freddyuk · 04-04-2019 8:26am

wexfordman2 wrote: »

Well, my 6kwp /5kwh battery system has been working great the last few days, the hot water diverted.got installed over the weekend.

So, I'm generating about 25kwh, exporting 5kwh, and importing 3kwh. The 3kwh import was night rate hours. My battery lasted till 11.25pm last night. And have immersion heated with that as well

Similar readings today so far.

That would be on a decent "solar day" but not on an average Irish day although with 6kwp you should be covering most of your day load as you should be getting around 450-500w out of the PV on a duller day with no sun? You need enough surplus to recharge the batteries without resorting to grid usage at night.

5kWh storage is not a lot especially if you are using batteries for immersion?? I would not think this is good for the system unless I have that wrong however the diverter will resolve that on good days.

niallers1 · 04-04-2019 12:02pm

wexfordman2 wrote: »

Well, my 6kwp /5kwh battery system has been working great the last few days, the hot water diverted.got installed over the weekend.

So, I'm generating about 25kwh, exporting 5kwh, and importing 3kwh. The 3kwh import was night rate hours. My battery lasted till 11.25pm last night. And have immersion heated with that as well

Similar readings today so far.

I'd say between March and the end of September you would fill the battery each day without having to charge from the grid.

I've only used 3kwh from the grid in the past 8 days. ( 4.2kw Solar PV 1.8kw East/2.4kw West and 4.8kwh battery)
Meter 54957 - on the 3rd of April
Meter 54954 on the 26th of March
Total used 3kwh

Set your washing machine,dryer , dishwasher on delay start and at a time when you are not using the the oven.

freddyuk · 04-04-2019 6:16pm

niallers1 wrote: »

I'd say between March and the end of September you would fill the battery each day without having to charge from the grid.

I've only used 3kwh from the grid in the past 8 days. ( 4.2kw Solar PV 1.8kw East/2.4kw West and 4.8kwh battery)
Meter 54957 - on the 3rd of April
Meter 54954 on the 26th of March
Total used 3kwh

Set your washing machine,dryer , dishwasher on delay start and at a time where you are not using the the oven.

Can you post the data from your system for the 8 days highlighted as I think others would be interested in knowing this is possible and it would support efforts to encourage more renewable energy take up.

niallers1 · 04-04-2019 6:26pm

freddyuk wrote: »

Can you post the data from your system for the 8 days highlighted as I think others would be interested in knowing this is possible and it would support efforts to encourage more renewable energy take up.

Hi Freddy, don't have the internet at home ( only in my phone) so I don't have the data. I took a photo of my meter over a week ago and another to compare so that's how I could see the usage.
Photo title date stamped.

freddyuk · 04-04-2019 7:39pm

niallers1 wrote: »

Hi Freddy, don't have the internet at home ( only in my phone) so I don't have the data. I took a photo of my meter over a week ago and another to compare so that's how I could see the usage.
Photo title date stamped.

I think that explains it as you appear to have an old analogue meter with a solar installation connected to the grid? The ESB would have installed a new meter to allow the installation officially. You say you are on a night rate so can this meter do that? I am a bit confused.

Did you apply to ESB for the installation and send the appropriate forms (N6) before installation? You need everything certified. This meter is likely going backwards when you export the solar power which is very illegal and explains your fantastic low reading! . If it is not all certified I recommend you should ask ESB to retroactively make your system legitimate or they can/will shut the system down. I think they take this very seriously as their employees lives are at risk here.

Or have I got this totally wrong?

niallers1 · 04-04-2019 7:48pm

freddyuk wrote: »

I think that explains it as you appear to have an old analogue meter with a solar installation connected to the grid? The ESB would have installed a new meter to allow the installation officially. You say you are on a night rate so can this meter do that? I am a bit confused.

Did you apply to ESB for the installation and send the appropriate forms (N6) before installation? You need everything certified. This meter is likely going backwards when you export the solar power which is very illegal and explains your fantastic low reading! . If it is not all certified I recommend you should ask ESB to retroactively make your system legitimate or they can/will shut the system down. I think they take this very seriously as their employees lives are at risk here.

Or have I got this totally wrong?

Hi Freddy, the only thing you have right in that entire post was the bit where you said you've got this totally wrong.
You've made a lot of false assumptions about me.

I sensed from your first question that you didn't believe.

1. I've never said I was on night rate . I think you are confusing me with someone else.
2. Yes. Form N6 sent to E.S.B. Without this you will not receive your grant from S.E.A.I.
In fact, my installation was also examined by an SEAI Inspector as I was one of the first to claim the new solar PV grant.
3. The meter in the photo cannot run backwards. If you look again at the photo. You will see a symbol under the disc that shows this.
4. That was an excellent week of solar. Readings for the month overall was closer to 2kwh per day. In March that's still very good.
5. I think your owe me an apology

wexfordman2 · 04-04-2019 8:26pm

freddyuk wrote: »

That would be on a decent "solar day" but not on an average Irish day although with 6kwp you should be covering most of your day load as you should be getting around 450-500w out of the PV on a duller day with no sun? You need enough surplus to recharge the batteries without resorting to grid usage at night.

5kWh storage is not a lot especially if you are using batteries for immersion?? I would not think this is good for the system unless I have that wrong however the diverter will resolve that on good days.

The battery is not being used for the immersion, only.the Pv.

The way it works, is Pv first powers.the house, and excess charges the battery . Only.once the battery is fully charged does the excess go.to.the immersion

This week so far, I generally find the battery to be fully charged and the immersion heated by about 10am.

This has been during good days, but more average, ie we have had haul, rain and sleet during the week.

Today, generated 23kwh, consumed 19kwh (that includes about 4.6kwh that went to the immersion). Of the 19kwh I generated, 15kwh was consumed. The battery is discharging, and I expect it to be fully discharged in about 2 hrs (used heavy in the evening today with oven on).

4kwh power imported, majority of which was night rate, so a cost of about 40c.

niallers1 · 04-04-2019 8:30pm

@wexfordman2 . Your usage seems high. Compared to our usage anyway. What's using so much?

wexfordman2 · 04-04-2019 8:45pm

niallers1 wrote: »

@wexfordman2 . Your usage seems high. Compared to our usage anyway. What's using so much?

If you exclude the hot water diverter, my consumption is about 15kwh for today, which I think would be about average.

We have good energy rated appliances,washer, dishwasher are all a++ rated, the dryer is a heat pump dryer, so also very efficient. Fridge and freezer would probably take most.of the idle.lad which is between 300 and 400 watts.

Our water pump also for the well, but obviously that's not running all the time.

Our esb bill pre solar was 130pm

What's your idle/background power ?

niallers1 · 04-04-2019 8:53pm

wexfordman2 wrote: »

If you exclude the hot water diverter, my consumption is about 15kwh for today, which I think would be about average.

We have good energy rated appliances,washer, dishwasher are all a++ rated, the dryer is a heat pump dryer, so also very efficient. Fridge and freezer would probably take most.of the idle.lad which is between 300 and 400 watts.

Our water pump also for the well, but obviously that's not running all the time.

What's your idle/background power ?

About 200 watts .
We try to leave nothing on standby, use LED bulbs and stagger appliances. One large appliance at a time. Kids are trained to turn off lights when they are not using a room which helps.

wexfordman2 · 04-04-2019 8:58pm

niallers1 wrote: »

About 200 watts .
We try to leave nothing on standby, use LED bulbs and stagger appliances. One large appliance at a time. Kids are trained to turn off lights when they are not using a room which helps.

Yep, all.my lights are led as well. I have a smart lighting system, so they are automatically turned on/off (tried training the kids....failed).

Help! I don't understand PV!

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