Solar panels

[hayfield]

With 2 days to go to my first year with panels I suddenly noticed something

 

I have a smallish system on a single story roof, the pitch is quite shallow and get a small amount of shading at the start and end of the day from trees in other gardens. 

The projection for the first year was 2205 kwh per year

 

With 2 days to go the system has generated 2467 kwh, as the forecast is not too good for the next 2 days I guess I should get 2475 kwh. This is 270 kwh above expectations  +12%

 

Looking at this calendar year the system has produced 2047 kwh in 8 months less than 200 kwh from the expected annual yield !!! this year the first 4 months yielded 671kwh, if the last 4 months is the same I will be impressed, November and December were really very poor, with prices going up an added bonus

 

My future projected costs is £1842*, this is at the old rates. If the tariff increases by 80% then I will have to find £3315. I know I have £900 in winter fuel payments and other government subsidies, I pay £1300 on ddi and have built up a £450 positive balance over the summer, excluding any further state help I guess I will have to add another £50 pm to my ddi in addition to using the state payments paid directly to me. I have noticed that the assumption is based only on my usage and takes no account of my exports so perhaps it may well need a lower increase to my DDI

 

* The projection takes no account of my export fees which increased greatly for the last 6 months owing to both a rate rise and increase of production

 

Thankfully like many of my age I have a bit of a safety net in our finances

 

What I would say to folk is to start to assess where you are in this awful state of affairs and if you can start making plans

[sjp23480]

Hi John@hayfield

 

Interesting post. 

 

My installation was finally completed yesterday late afternoon.  So this my first full day generating power.

 

My 7 panels yielded 7kwh, but it was a really cloudy.  I exported 3kwh, the 3.5kw battery charged 100% - so I must have used 0.5kwh.

 

Total consumption was 14kwh and I imported 9kwh (dishwasher!), approximate cost of £2.60. (based on current unit rate £0.29/kwh).

 

Had I used 14kwh off grid, the cost would have been £4.06, saving £1.46.  That will increase to £2.60 saving on the new rate (£0.52/kwh)

 

Lets see how it goes tomorrow, but the system will not offset the increase in the cap - so I will have to figure out what my new DD should be.

 

Steve

 

 

 

 

[hayfield]

Steve

 

I guess your batteries were partly charged to start with, I have no way of recording exports as I have to rely on Octopus records. But with my own experience even on the worst days I use a decent percentage of what I produce

 

30th  produced  5.4 kwh used 2.1 kwh

31st  produced 10.8 kwh used 2.2 kwh

 

14 kwh is quite a high use, on a Sunday when we use both the oven for a roast plus the dishwasher 9/10 kwh is a high usage, Our normal weekly usage is about 50 kwh ranging between 45 at the lowest range to 55 at the top

 

One of the few details I do not record is total production weekly, at best I have topped 100 kwh per week, my worst was 20 kwh for last December, This January was not much better at 44 kwh. But these two months were one of the lowest on record for sunlight. Over an 8 day period last December I produced 1.8 kwh, some days barely registering 0.1 kwh for the day !!!

 

But like my monthly DDI I pay more than I need to in the summer to keep my winter payments lower, solar panels are much the same, the bulk of production is April to September 6 months. November through Feb (4 months) is very low (235 kwh). So looking at the whole year is a better measure on a cost benefit basis. This year the 4 winter months will be very expensive

 

Your estimation of 52p per kwh is quite frightening, if that's the case hopefully our export tariffs will rise pro rata (7.5p to 13.5P) but the margined between export and import rates is totally unfair on non commercial users, and I am with one of the better payers 

[Ouroborus]

A couple of questions to those in the know.

 

Is there any merit to having more batteries than the solar pv's can *normally* charge  (ie, avoid any exporting of energy)

What's the typical time to charge  a (eg) 9Kw battery

Best place for batteries to be sited - indoors or outdoors.

 

thanks

Edited September 2, 2022 by Ouroborus

[sjp23480]

9 hours ago, hayfield said:

Steve

 

I guess your batteries were partly charged to start with, I have no way of recording exports as I have to rely on Octopus records. But with my own experience even on the worst days I use a decent percentage of what I produce

 

30th  produced  5.4 kwh used 2.1 kwh

31st  produced 10.8 kwh used 2.2 kwh

 

14 kwh is quite a high use, on a Sunday when we use both the oven for a roast plus the dishwasher 9/10 kwh is a high usage, Our normal weekly usage is about 50 kwh ranging between 45 at the lowest range to 55 at the top

 

One of the few details I do not record is total production weekly, at best I have topped 100 kwh per week, my worst was 20 kwh for last December, This January was not much better at 44 kwh. But these two months were one of the lowest on record for sunlight. Over an 8 day period last December I produced 1.8 kwh, some days barely registering 0.1 kwh for the day !!!

 

But like my monthly DDI I pay more than I need to in the summer to keep my winter payments lower, solar panels are much the same, the bulk of production is April to September 6 months. November through Feb (4 months) is very low (235 kwh). So looking at the whole year is a better measure on a cost benefit basis. This year the 4 winter months will be very expensive

 

Your estimation of 52p per kwh is quite frightening, if that's the case hopefully our export tariffs will rise pro rata (7.5p to 13.5P) but the margined between export and import rates is totally unfair on non commercial users, and I am with one of the better payers 

Hi John,

 

The 52p /kwh is not an estimate.  That is the new price cap from October 1st, but few outlets report the per kwh rate - less sensational than to say how many £000s households will be paying. 

 

Scarier still is the prediction that the per kwh rate will go up to 80p-92p range from January 1st 2023!

 

I found this article from ICAEW with the per kwh rates: https://www.icaew.com/insights/viewpoints-on-the-news/2022/sept-2022/chart-of-the-week-energy-price-cap-update.

 

By way of an update, day two (so far) yielded 10kwh, I imported 1kwh, and used 9kwh, the 3.5kwh battery is 99% charged.

 

Steve

[sjp23480]

3 hours ago, Ouroborus said:

A couple of questions to those in the know.

 

Is there any merit to having more batteries than the solar pv's can *normally* charge  (ie, avoid any exporting of energy)

What's the typical time to charge  a (eg) 9Kw battery

Best place for batteries to be sited - indoors or outdoors.

 

thanks

@Ouroborus

 

I think you might want to talk to an expert. 

 

I guess the charging time depends on the capacity of the battery and the number of panels feeding it.  

 

I suspect you should start by looking at your consumption data, that should determine the configuration you need.  Our advisor said it was not worth selling kwh to the grid, the best available rate is <10p/kwh.  So the payback is very slow.  

 

On average my daily consumption is <10kwh per day, so the system is configured to cover these needs.

 

The battery is in the loft space close to the inverter and related circuitry.

 

Steve

 

[Ouroborus]

17 minutes ago, sjp23480 said:

@Ouroborus

 

I think you might want to talk to an expert. 

 

I guess the charging time depends on the capacity of the battery and the number of panels feeding it.  

 

I suspect you should start by looking at your consumption data, that should determine the configuration you need.  Our advisor said it was not worth selling kwh to the grid, the best available rate is <10p/kwh.  So the payback is very slow.  

 

On average my daily consumption is <10kwh per day, so the system is configured to cover these needs.

 

The battery is in the loft space close to the inverter and related circuitry.

 

Steve

 

 

Thanks Steve,

 

As you picked up, I'm keen to avoid selling electricity back to the grid.  At the moment, my old rotary meter goes backwards on a sunny day when the existing panels are working.  But having three teenage kids means its never negative for long.   A battery means the proposed additional solar panels will get charge this first and any surplus will go back to the grid and the meter goes backwards again.  Which, to be fair, is a win win position for me.   I could avoid the battery and just dump the excess back into the grid, but i fear with this method that the utilities may eventually smell a rat and force a smart meter on me.  The cash is sitting in the bank, inflation eroding it and pushing up the prices of installs, so maybe a battery now may save money later.

 

But looking further ahead, if i get a smart meter forced on me, I'll be looking for ways to avoid export, which may mean additional batteries to fully capture the solar energy produced.  The combined pv array would be around 9kw.  During winter, clearly the solar will be minimal, so the use of overnight cheap rate electricity to charge up the battery/s is an idea.  But it's only cheap for four hours and if you can't charge the battery/s in that time, its not worth it.

[sjp23480]

@Ouroborus i hear you, one of mine has left home in the last year but the other one is still here and shows no sign of budging!

 

Batteries seem to run out at about £1000/kw, my 3.5kw cost just over £3000.  9kw will be quite expensive. 

 

One thing I noticed yesterday was that we ran a couple of appliances simultaneously last night, I assume the combined load exceeded the capacity of the battery.  So we started importing from the grid to cover the deficit, although the battery still had charge.  Lesson learned!

 

Not sure about the overnight charging, we don't have a "white meter", so I can't comment on the benefit.  Given the cost of the battery the return will hinge on the relative difference between the day and night rates.

 

Good luck,

Steve

[Tony_S]

1 hour ago, sjp23480 said:

Not sure about the overnight charging,

Our SEG contract from EonNext requires that our batteries cannot be charged from the cheaper overnight electricity. We must be managing the panels and batteries quite well as we have only bought a couple of kWh from the grid this summer. 

[Ian Morgan]

 

2 hours ago, sjp23480 said:

One thing I noticed yesterday was that we ran a couple of appliances simultaneously last night, I assume the combined load exceeded the capacity of the battery.  So we started importing from the grid to cover the deficit, although the battery still had charge.  Lesson learned!

 

 

It is the maximum capacity of the inverter that is important here. Mine can support about 4kW. That is, it can supply the house with a maximum of 4kW, as a sum total of the solar panels output, topped up by the battery if and when required. If the house needs more than 4kW at any time (electric shower, tumble dryer or car charger), anything over the 4kW will come from the grid. If the sun has gone and the battery is exhausted, it must all come from the grid. My setup has been configured so that the battery stops discharging at 10% capacity.

 

I have a 10kWh battery, and on an averagely sunny day it has charged from 10% to 100% in about 5 or 6 hours, while still supplying the basic needs of the house (fridge, freezer, kettle, computers, TV, etc) which is 200-300W.

 

[hayfield]

17 hours ago, Ouroborus said:

A couple of questions to those in the know.

 

Is there any merit to having more batteries than the solar pv's can *normally* charge  (ie, avoid any exporting of energy)

What's the typical time to charge  a (eg) 9Kw battery

Best place for batteries to be sited - indoors or outdoors.

 

thanks

 

I am no expert and my aim is to make the best use of both my spending and saving

 

The amount yo can charge will vary depending on both the weather and season, in the summer the sun is higher, daylight hours are longer and the weather is better

 

My worst days in the winter yielded 0.1 kwh, no chance of using any of my own production let alone charging  batteries, in the summer my system was maxing out at 16kwh per day.  My average daily consumption is about 7 kwh per day. 

 

Buying a system to save all the energy you produce would be very expensive and rarely used to its maximum, surplus energy is not lost as you get paid for exporting and if you are looking at the best use of your funds extra panels may be more cash efficient than extra batteries

 

A year ago a small set of batteries would have cost me an extra £5,000, the return on capital I felt was not worth it

This year I received another quote which was now £3,600. On the face of it the numbers looked promising until I deducted the lost export fees

 

No doubt batteries will save money and if rates increase by 80% the numbers will change. But we are looking at in the medium term rates decreasing according to the experts from the currant price hikes. For me its all about the cost verses the benefit

 

The other thing is its a price cap and if power becomes cheaper prices will reduce, the way electricity prices are calculated is broken, its worked out on the highest cost not the overall cost, the cost of producing solar, wind and nuclear power has not risen but we are being charged for gas across all of the power, likewise when gas is cheap we are being charged for the highest power cost. The system is broken and needs sorting out. How Offgem has allowed this failed system to continue is beyond me. Seemingly they have failed the consumer totally 

[Ouroborus]

Thanks John,

 

With my family, I know i'm not going to be off-grid, its all about limiting the damage.   Jun to Jul this year saw us use 15kw per day, that's with an existing 4kw pv array fitted.

 

You lost me a little when you mentioned lost export fees.  With the FIT now closed to new installs, any surplus electricity needs an export agreement with a utility company.  I know the payments for these vary, but lets say 7p per Kw as an average.  I currently buy electricity from Shell at 29p per kw.     

 

So to my thinking (could be wrong here!), with a smart meter every unit I export during the day, but buy back in the evening is 7p - 29p = - 22p.  A 22p cost per unit.   If I had a fully charged 9kw battery and minimised export, then give or take, its 9*22 per day (£2) saved, So in ideal conditions where the battery charges to 100% every day, I save £2 per day, thus payback for the battery (£3500), is five years.   But how much would that battery charge in winter?

 

---

 

During winter, I'd perhaps look to charge the battery over night on the cheaper rates and looking at charging times for EV cars, it would suggest it should take 3.5 hours.  Based on the Octopus Go rates at the moment, 7.5p/40p, i'd likely be worse off under this tariff due to higher peak prices, especially if mains charging is a slow affair and the battery cannot be fully charged.  If there were two batteries, do they charge at the same rate as one?

 

--

 

Without my current setup, (no smart meter) whatever is exported saves me 29p per unit.  No problems in winter, could raise an eyebrow in the summer.  £ for £, a purely solar system with no battery is the best option for me right now, but it all depends if a smart meter becomes mandated and i can no longer freely export the surplus.

 

 

 

Sorry for rambly post.  Some of this would seem to be thoughts to myself to discuss with the installer!  

 

 

 

[Ian Morgan]

Please note the important difference between kW and kWh. Some posts seem to confuse the two.

 

kW (kiloWatt) is a measure of power at a particular instant in time.

 

kWh (kiloWatthour) is a measure of energy, power supplied or consumed over a period of time.

 

A 10 kWh battery could, in theory, supply 1kW of power to a cooker for 10 hours. Or it could light a 100W bulb for 100 hours, or a 5kW emersion heater for 2 hours.

 

My solar panels can produce a maximum of 4kW of power. If sunny enough to produce full power for long enough, with no other items in the house using power and super efficient charging, it could theoretically fully charge a 10kWh battery in two and a half hours (4kW x 2.5h = 10kWh).

 

Hope this helps.

[hayfield]

2 hours ago, Ouroborus said:

Thanks John,

 

You lost me a little when you mentioned lost export fees.  With the FIT now closed to new installs, any surplus electricity needs an export agreement with a utility company.  I know the payments for these vary, but lets say 7p per Kw as an average.  I currently buy electricity from Shell at 29p per kw.     

 

 

 

 

Sorry my reply was misunderstood. I will try again

 

When this years quote came in at £3600 instead of £5000 looking at it at face value it might be worth ordering one.

 

I think it was for 4 kwn in size, that would cover me for most of the days where I am producing 7+ kwh, but according to my initial quotation it would provide 52% of my needs.

The annual assumption for usage is 3400kwh, 29% =  986 kwh  @ £0.29  £294 pa, this is at the currant rates and when I made the decision the experts were saying prices would fall from January.

 

The return of £294 on an investment of £3600 looks much better than the year before, but I will loose what Octopus is paying for the energy I will not be exporting  (986 kwh x 7.5p) £74. so the real return is £220 on an outlay of £3600

 

The fact is my system id projected to provide 36% of my energy needs, with a battery this increases by 44% to 80%

 

If I had a few extra panels the return against expenditure would be better than buying batteries.

 

My system due to its size and out weather would only ever produce enough power per day to service my daily requirements for a maximum of 6 months of the year. Last December I only produced 20 kwh all month, I need at least 220 kwh a month

 

[sjp23480]

So last night I went to bed and the battery was >90% charged and had exported nothing to the grid.  By the time I checked this morning (8am), the battery was showing 15% charged, I had exported 3kwh to the grid and drawn 2kwh overnight from the grid.  Is this normal?  It looks like the battery discharged to the grid and then I had to draw 2kwh to make up the difference.  This makes no sense to me, I'd prefer the battery to retain the charge, not export and not draw from the grid - which was the case the night before.  I am a bit confused.

 

Today, my 7 panels produced 9kwh, I consumed 11kwh and the battery is only 20% charged as of now, so I will be drawing from the grid again tonight.

 

At one point today we were consuming 3kwh, but as far as I could see we did not have any appliances running, other than the fridge/freezer and other small stuff.  I couldn't understand why we were consuming so much power.  

 

I also keep getting persistent alarms about the inverter "MET_Comm_Fail" apparently and I need to restart the inverter and meter, but the installers haven't provided any instructions on this despite them saying they would send instructions.

 

The wife is also starting to get a bit wound up by my fixation, but I expect the novelty will wear off once the configuration is optimised.

 

Steve

 

 

 

 

[hayfield]

Yesterday was the last day of having a system working for 365 days, as I keep saying the projection was for 2205 kwh production and it came in at 2483 kwh a 12.6% increase. As for £'s the energy crisis absolutely blew the calculations out of sight. Given last December was such a wash out a full calendar year is the next target

[Vistisen]

On 02/09/2022 at 16:24, Ouroborus said:

A couple of questions to those in the know.

 

Is there any merit to having more batteries than the solar pv's can *normally* charge  (ie, avoid any exporting of energy)

What's the typical time to charge  a (eg) 9Kw battery

Best place for batteries to be sited - indoors or outdoors.

 

thanks

This must depend on two factors, the price you get for selling electricity, and the cost of extending batteries. I have 10 kW of batteries and have only been up and running since May, so it is too early to tell for me whether I should use more but I suspect the answer will be no. I have made an excel spreadsheet that I use to track all the (many) datapoints I can get from my system. Here in Denmark we have no price cap, and as soon as you are registered as a supplier of electricity, you can only choose to be billed for the variable hourly rate for consumption. This last week’s prices, including taxes, have swung between about 30p and £1.20 for a kW

My selling price is the spot rate price, (which is set hourly). minus 1 penny. This in reality means that the cost of extending the battery has to be paid for by the saving of taxes on the extra energy I consume, rather than sell.  So, for me it is not viable.

Batteries normally need to be frost free. (Although our Huawai batteries can be outside). Ours are in a utility room, They and the invertor do actually generate a bit of heat. Which pleases the dog who sleeps up against them.

[Vistisen]

Another important factor is the size of your inverter. If you are using more power than it has the capacity to provide, it does not matter how much you have in the battery and/or are getting the solarpanels. Your will always be buying the extra Watts from the grid. This seems to an often-overlooked factor. When browsing forums, I see a lot of posts like ‘we have power in reserve, why are we still consuming electricity from the gird?’ This is especially the case when charging electric cars. 

This can be shown clearly here. We are charging a car, therfore using about 9.5kW. Our inverter can cope with 8.8Kw, så we are using 5.145 kW from the solar panels, 3.654 kW fronm the battery and buying the laste 0,758 kW from the grid.

 

Edited September 4, 2022 by Vistisen

[Tony_S]

16 hours ago, sjp23480 said:

 

I also keep getting persistent alarms about the inverter "MET_Comm_Fail" apparently and I need to restart the inverter and meter, but the installers haven't provided any instructions on this despite them saying they would send instructions.

 

The wife is also starting to get a bit wound up by my fixation, but I expect the novelty will wear off once the configuration is optimised.

https://ginlongsolis.freshdesk.com/support/solutions/articles/36000308050-met-comm-fail-and-rs485-fail-troubleshooting
 

I don’t think sending restart instructions for this fault will be adequate. From the process described in the above article you need a site visit and wiring check or replacement. 
Hope this helps

Tony

[Tony_S]

On 02/09/2022 at 15:24, Ouroborus said:

Best place for batteries to be sited - indoors or outdoors

Mine are in the garage next to the inverter and all the fuse boxes. 
The garage is a semi integral to the house type. We fitted a heat alarm above them as recommended by the installers. I had to fit a linked type alarm as we couldn’t hear it from the house. 

Still space for one more in the rack. 
Tony

[sjp23480]

10 hours ago, Tony_S said:

Mine are in the garage next to the inverter and all the fuse boxes. 
The garage is a semi integral to the house type. We fitted a heat alarm above them as recommended by the installers. I had to fit a linked type alarm as we couldn’t hear it from the house. 

Still space for one more in the rack. 
Tony

@Tony_S

 

Interesting picture, my battery (I only have one) is not in a rack-it is just stood on the floor in the loft,like yours next to the inverter and the other circuitry.   The battery is unlikely to get moved, but should it be in a rack and the installers mentioned nothing about a heat alarm?

Steve

[sjp23480]

12 hours ago, Vistisen said:

Another important factor is the size of your inverter. If you are using more power than it has the capacity to provide, it does not matter how much you have in the battery and/or are getting the solarpanels. Your will always be buying the extra Watts from the grid. This seems to an often-overlooked factor. When browsing forums, I see a lot of posts like ‘we have power in reserve, why are we still consuming electricity from the gird?’ This is especially the case when charging electric cars. 

This can be shown clearly here. We are charging a car, therfore using about 9.5kW. Our inverter can cope with 8.8Kw, så we are using 5.145 kW from the solar panels, 3.654 kW fronm the battery and buying the laste 0,758 kW from the grid.

 

@Vistisen

 

Thank you so much for posting this.  I had trawled the internet trying to find something to explain the issue. I shall now be reaching back to the installers and arrange a fourth visit to take a look!

 

Steve

[Tony_S]

49 minutes ago, sjp23480 said:

@Tony_S

 

Interesting picture, my battery (I only have one) is not in a rack-it is just stood on the floor in the loft,like yours next to the inverter and the other circuitry.   The battery is unlikely to get moved, but should it be in a rack and the installers mentioned nothing about a heat alarm?

Steve

The batteries we have are designed for rack mounting. Each one is 2.4kWh capacity. I don’t know how they would have mounted just one in our garage. They claim to have all kinds of heat overload protection anyway but having received the advice from our installers I looked at lithium battery fires on YouTube and ordered a Fireangel heat alarm! The YouTube videos were big industrial batteries not like ours but it was a good excuse to upgrade all the fire /smoke alarms in the house. 
 

[sjp23480]

10 hours ago, Tony_S said:

The batteries we have are designed for rack mounting. Each one is 2.4kWh capacity. I don’t know how they would have mounted just one in our garage. They claim to have all kinds of heat overload protection anyway but having received the advice from our installers I looked at lithium battery fires on YouTube and ordered a Fireangel heat alarm! The YouTube videos were big industrial batteries not like ours but it was a good excuse to upgrade all the fire /smoke alarms in the house. 
 

@Tony_Sthanks Tony, I will investigate the alarm situation. 

 

Steve

[Kris]

I got told today that there is a 2 month wait for an initial consultation, 6 month wait for a quote and 10 month wait for installation of new systems. This came direct from a company I have dealt with before.