Navitron Renewable Energy and Sustainability Forum

Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: NugentS on May 05, 2019, 07:47:18 PM



Title: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 05, 2019, 07:47:18 PM
All,

Back in 2012 (I think it was) I put 4Kw of Solar PV (Sanyo HIT's) up on my roof. Cost was approx 11K (I found a receipt), has consistently overachieved the official production figures and I am very very pleased with it. I haven't counted, but it may even have paid back (the gross figure anyway). It is a well worth it investment. I was happy with anything between a 7-12 year payback and it will easily achieve that (disasters not withstanding and as long as those effing pigeons just b$^^er off)

I use a lot of power 24*7 due to computer equipment running 24*7, had disk drives etc all of which costs quite a lot of money every month.

I also have an EV (albeit a small one) (for about 3 weeks now)
I am currently switching to Octopus Go. The car takes about 4 hours to charge from flat on a 16Amp charger and Octopus go gives a 4 hour cheap rate at 5p/minute - which all seems a no-brainer

For a while now I have been looking at battery systems - but they just haven't made sense financially, either too small, or too expensive or both.

However I have just gone over my man maths - and have a large spreadsheet that says I can save £435 a year (possibly a bit more) by putting in a large enough battery. I am assuming a battery with 11kWh of useable capacity. The battery would charge during the cheap rate, and when my solar output exceeds my usage. On a very good day I would still export power and on bad days I would obviously import. The numbers almost work - close enough that all other questions being answered correctly, and my maths being correct I am prepared to pull the trigger on this one. Payback in the region of 10-12 years is what I am looking for.

Does anyone have any thoughts / advice / comments

Do Navitron do battery systems?

Regards

Sean






Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: RIT on May 06, 2019, 12:01:42 AM

Do Navitron do battery systems?

Regards

Sean


It would be best to just give them a call as there is very little on their website apart from a few PV inverters with builtin chargers.


As for your figures with the detail you have provided you seem to be expecting to cycle the batteries daily. Only you can know if you will manage to do this, considering 4 hours of the day you will have access to low-cost power from Octopus and during the daytime, the PV will be providing you power.

If you do not manage a daily cycle your payback period will lengthen. One comment I make to anyone who plans to install batteries is that you have to factor in 2 other things when calculating the payback.

   - The money could be earning interest - so even at today's poor rates it is something to take into account.
   - In general, the cost of battery storage has been falling every year. So you should take into account the cost of doing something today compared to waiting.

The other question is how much more efficient can you make your IT environment if you instead invested in that? I once had a fair stack of servers, but in the end I virtualized them to a single system and replaced all the 24x7 spinning rust with SSDs. The NASs I owned only started up when the backups were due to run. I ended up with a 80% power saving and a much quieter environment.



Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: linesrg on May 06, 2019, 07:22:12 AM
Sean,

You quote an annual saving figure of £435 per annum and we have to assume you have factored everything in.

You will see from postings elsewhere that whenever the Octopus Go tariff comes up I have always been somewhat sceptical of any claims they make but I'm prepared to accept that if you can maximise their cheap periods then you might make some savings but I have found that taking the charges they make at other times of day outweigh any advantages.

Generally speaking, for the majority, I don't yet think there is a financial case for installing batteries.

Yes I've done it and discovered, when you add everything up (and I'm sad enough to do that), that even with a 'cheap' install using second hand equipment, where possible, the sums probably still don't add up.

The best I can say about mine is that it makes me feel better and overall it is reducing my impact on the planet.  (Do SMA quote figures for when their pieces of equipment become 'carbon neutral'?)

RIT's suggestion looks like it may be a more logical approach.

Regards

Richard


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: Stig on May 06, 2019, 07:50:16 AM
Another thing to check would be the small print of your Octopus Go tariff - is there a minimum day/night ratio or will they really let you run 100% of the cheap rate with no daytime usage?


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: dan_b on May 06, 2019, 09:12:00 AM
Did you use my referral code to switch to Octopus? That would give you an extra £50 to play with  :laugh:


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: dan_b on May 06, 2019, 09:15:26 AM
Here it is

https://share.octopus.energy/teal-leaf-367


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 06, 2019, 09:16:51 AM

Do Navitron do battery systems?

Regards

Sean


It would be best to just give them a call as there is very little on their website apart from a few PV inverters with builtin chargers.


As for your figures with the detail you have provided you seem to be expecting to cycle the batteries daily. Only you can know if you will manage to do this, considering 4 hours of the day you will have access to low-cost power from Octopus and during the daytime, the PV will be providing you power.

If you do not manage a daily cycle your payback period will lengthen. One comment I make to anyone who plans to install batteries is that you have to factor in 2 other things when calculating the payback.

   - The money could be earning interest - so even at today's poor rates it is something to take into account.
   - In general, the cost of battery storage has been falling every year. So you should take into account the cost of doing something today compared to waiting.

The other question is how much more efficient can you make your IT environment if you instead invested in that? I once had a fair stack of servers, but in the end I virtualized them to a single system and replaced all the 24x7 spinning rust with SSDs. The NASs I owned only started up when the backups were due to run. I ended up with a 80% power saving and a much quieter environment.



I can absolutely cycle the batteries daily - my base load deals with that superbly. No issue whatsoever with that.
Interest is IMHO irrelavent at this stage (and available rates)
Yes batteries are falling in price - but I have found that if one keeps waiting for a better price then one never does anything. In 10+ years time batteries will be different. Solid State maybe, smaller, higher energy density etc. Who knows. Deal with that in 10 years time.

My IT infrastructure has 3 servers, 2 on all the time (I can't get it down to one - I have tried, the second server just uses too much CPU [Plex]) and one powered off for power savings / spare
3 NAS's (1 does iSCSI storage on SSD's) for VMWare, 1 does primary storage and the last only turns on for backups during the 4 hour period. I also have a 4th NAS belonging to a friends company they offsite backup to it during the 4 hour period after which it turns off. I charge them for that - so don't really count the electricity cost.

All setup in preparation for the new Tariff.

Note that my estimated saving is 435 in year one. If electrickery prices go up, so does my saving bringing the payback period down. Of course if Octopus vanish in a puff of smoke then things will get a little more difficult

Sean


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 06, 2019, 09:17:34 AM
Did you use my referral code to switch to Octopus? That would give you an extra £50 to play with  :laugh:

Sorry - I used someone else's.

Sean


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 06, 2019, 09:19:52 AM
Another thing to check would be the small print of your Octopus Go tariff - is there a minimum day/night ratio or will they really let you run 100% of the cheap rate with no daytime usage?

I'll still have some daytime usage as I am not sizing for peaks - which are transient.

Sean


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: Countrypaul on May 06, 2019, 12:48:54 PM
Just out of curiosity, how long do Octopus gaurantee to keep this tariff? Could they suck customers in for a couple of years and then abandon it forcing users to accept a higher tariff or change supliers? If so how do you factor that (and teh going up in a puff of smoke) into calculations?


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 06, 2019, 01:40:32 PM
Honestly I don't

If I worried too much about what might happen, again I would never do anything. I suppose I could always shift to an alternative E7 tariff. It would be unlikely to be as good but wouldn't be too bad.

Sean


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: nowty on May 06, 2019, 02:05:10 PM
Last year I was hopeful of getting a 6p cheap rate Economy 7 deal, when there were a few of them still available. But by the time I got round to having the E7 meter fitted, the cheap rates had gone up to near 10p.

The Octopus deal (5p /kWh for 4 hours) sounds good but there is a 25p per day standing charge which would reduce my savings to almost nothing. And now their website says,

"PLEASE NOTE: We’ve currently paused taking new smart installation appointments as we begin a more controlled SMETS2 rollout over the next few months. If you don't want to wait on one of our standard tariffs in the interim, we'd recommend delaying your switch until we've started taking appointments again."

So missed the boat there.

There is another similar deal with Scottish Power at 4.74p /kWh for 5 hours, seems fixed until Jan 2021, but you need to have an EV registered at your supply address and they seem to want their Standing Charge to be a closely guarded secret.


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: kristen on May 06, 2019, 02:11:35 PM
If electrickery prices go up, so does my saving bringing the payback period down

My Man Maths would also include that IF i already had Battery installed I was in better position to take advantage of some other opportunity in future e.g. TOU metering - whereas a new Rate coming along, and then it taking me X-months to get Battery and have it installed (assuming that I had Cash at that point), would mean missing the boat somewhat.

Will your battery be UPS?  That's one of the main reasons I want a battery - each 10 second power cut as something external trips/resets/reroutes takes drown all my IT gear and several minutes until it is upright - plus whatever work I lost


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 06, 2019, 03:57:04 PM
I wasn't planning on UPS - no.

All my computer equipment (that matters) is on UPS power anyway and and is on programmed shutdowns if the power goes out. The grid is reliable where I live so UPS seems to be not required

Sean


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: kristen on May 06, 2019, 04:14:49 PM
I wasn't planning on UPS - no.

The piddly individual UPSs we have seem to have a lifetime less than power cut frequency, so I'll be happy to replace them with a more robust "whole building UPS", that also gets me lighting etc. and thus a better ability to actually work albeit not the "indefinite supply" of a generator (I do have generator socket on outside of building, and a change-over-switch, so in principle I cold run generator to allow PV to generate ... and replenish Battery ... but no idea if that is pipe-dream or possibility)

My supply is reliable, but we have a momentary outage often enough to be annoying, and then a "JCB went through the cable" 4-hour outage probably once every year or two - even I had done that, and taken out all my neighbours  whistle

When we had the building rewired I wish I had had the foresight to separate "essential circuits" so I could more easily configure the building to run on reduce power


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: linesrg on May 06, 2019, 05:52:53 PM
Last year I was hopeful of getting a 6p cheap rate Economy 7 deal, when there were a few of them still available. But by the time I got round to having the E7 meter fitted, the cheap rates had gone up to near 10p.

The Octopus deal (5p /kWh for 4 hours) sounds good but there is a 25p per day standing charge which would reduce my savings to almost nothing. And now their website says,

"PLEASE NOTE: We’ve currently paused taking new smart installation appointments as we begin a more controlled SMETS2 rollout over the next few months. If you don't want to wait on one of our standard tariffs in the interim, we'd recommend delaying your switch until we've started taking appointments again."

So missed the boat there.

There is another similar deal with Scottish Power at 4.74p /kWh for 5 hours, seems fixed until Jan 2021, but you need to have an EV registered at your supply address and they seem to want their Standing Charge to be a closely guarded secret.


Mike,

I'm currently on the Scottish Power web site. Having identified I have an Economy 7 meter I can see no sign of a 5 hour 'cheap' period on the 'Green Electric Vehicle' tariff. It's a SC of £0.4603, Day £0.18575 & Night £0.09432, these prices include VAT.

The 'Smartpower Green Electric Vehicle' tariff appears to have a SC of £0.00 and doesn't actually quote any unit rates so I'm very confused.

After a bit more trawling......The Scottish Power site is truly f*****g awful, they have deliberately gone a very long way to avoid telling you what their tariffs actually are. I suspect it must be bordering on being in breach of tradings standards.

I got this from an EV Forum

I called them and on the 4th attempt got through to someone. I was then switched to customer services who gave me the numbers:

Peak 15.281p
Off-peak 4.736p
Standing charge 19.81p


You also need to fit one of their vehicle chargers which is controlled by a mobile app. apparently.

Regards

Richard


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: RIT on May 06, 2019, 07:37:44 PM

You also need to fit one of their vehicle chargers which is controlled by a mobile app. apparently.


And that is where the whole thing turns into a scam. The Wallbox's website quotes an install cost of one of its chargers at £1,628 before any grant rebate. Part of the cost is £350 for "Mandatory UK circuit protection DC & Earth Protection", which is basically BS as they also have a £420 installation pack fee, which should be enough to cover the cost of an earthing rod. With luck the new Zappi point should kill this type of fee off when it ships as "in most cases an earth rod is not required during the install". Quotes for the installation of the old Zappi seem to have been around £1,000 before the grant rebate and that would have included earthing.

All in I think any advantage in taking this tariff for it's lower per kWh off-peak rate is created by them overcharging for the EV charger.


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: linesrg on May 06, 2019, 08:41:40 PM
Good Evening All,

Yet again when I go to the energy comparison web sites, even though I'm now down to seeking a quote based on circa 7000kW year with 42% on Economy 7, those nice people at bulb still come out top................

I have no connection with them but in terms of price and customer service I do wish I'd stayed with them and not transferred to Economy Energy and nor would I still be waiting for the incompetents at Ovo Energy to get my meter registered on the National Database so I can transfer back to bulb  banghead:

Regards

Richard


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 08, 2019, 05:58:03 AM
Octopus also have an "agile" tariff which tracks the wholesale price of electricity, marks it up and then charges you that price on a 30 minute basis
They advertise that sometimes prices go <0.00 p/unit. I guess not for long though.

Looking at their charts though and last years price. The average was 13.7921775p/unit (inc VAT) and a Median of 11.74 (inc Vat) with three instances of < £0.00 for a total of 1.5 hours so my gut feeling is that this would not suit me if I am timeshifting / EV charging.

Its interesting looking at the figures how it changes and might suit some people. But I am not convinced.

Sean


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: kristen on May 08, 2019, 07:47:27 AM
They advertise that sometimes prices go <0.00 p/unit. I guess not for long though.

Not sure about "not for long" ... if someone is paying for curtailment presumably they would prefer to give you the juice at least than the cost of curtailment penalty?

May see that more and more, with ToU metering etc ?

Quote
might suit some people

Static battery people maybe?


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: brackwell on May 08, 2019, 04:25:58 PM
Curtailment and zero £ leccy are not really that connected.  Curtailment comes from there being to much RE production which cannot be got to the places it could be used usually because there is a bootleneck on the grid. This was common with Scottish RE wind producing more than could be transmitted South to area of demand and was relieved with the completion of the Western link.  Zero prices come about as a product of supply not equaling demand ie to great a supply and there being no generator being short of his quota and therefore no one willing to buy and that can even be pumped hydro if the supply is to great for the supply cables/turbines.



Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: kristen on May 08, 2019, 05:09:39 PM
Curtailment

Sorry, my bad. I guess we need to get beyond infrastructure no longer requiring curtailment, and then into the situation where we have have too much Solar or Wind, and that then has to be dumped onto the market - for those that can consume it.

Or maybe with every car an EV and every meter Smart, by then, there will always be "somewhere" the surplus electrons can be parked?


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: RIT on May 09, 2019, 12:03:21 AM
Curtailment

Sorry, my bad. I guess we need to get beyond infrastructure no longer requiring curtailment, and then into the situation where we have have too much Solar or Wind, and that then has to be dumped onto the market - for those that can consume it.

Or maybe with every car an EV and every meter Smart, by then, there will always be "somewhere" the surplus electrons can be parked?

We already have that, generators who do not have CfD/FiT agreements drop out of the market as the market price drops below their cost of production. While most large scale wind is current under CfD agreements much of the gas-powered generation is not. You can see this on the gridwatch graphs for today. While wind output has remained fairly constant the gas based generators have a distinct day time/night time output cycle with a small recordable dip in the middle of the day if it is nice and sunny.

By 2030 there is expected to be another 20GW of wind capacity in the pipeline, with the hope that not all of it will be linked to CfD agreements. This could cause us to start talking about zero gas days, but the wind generators without a CfD will shut down if the market price drops below their wear and tear running costs.


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: kristen on May 09, 2019, 07:48:50 AM
wind generators without a CfD will shut down if the market price drops below their wear and tear running costs.

Ah, I hadn't considered that. The current negative-price offers (I'm thinking more about Texas customers, rather than UK ones) are presumably because of generation that can't be switched off.

Rats ... so no negative priced leccy for my batteries :(

I suppose that will crate opportunity for Generator to do local storage - once storage price makes that worthwhile


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: jonsamcor on May 10, 2019, 10:52:00 PM
I need to underscore my lack of knowledge .... the majority of this thread may as well be written in Hebrew, ....i know nothing.....so a battery install to help balance out my turbine generation is good or bad...??
Amazingly I did get a B in both maths and physics GCSE ......
Does it help ...? Does it f**k


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: RIT on May 10, 2019, 11:43:15 PM
I need to underscore my lack of knowledge .... the majority of this thread may as well be written in Hebrew, ....i know nothing.....so a battery install to help balance out my turbine generation is good or bad...??
Amazingly I did get a B in both maths and physics GCSE ......
Does it help ...? Does it f**k

It's good in terms of you being able to reduce the amount of energy you have to pull in from the grid, but it is often bad from a financial point of view as the lifetime cost of the battery solution can be greater than the savings that you see.

The lifetime cost takes into account at least the purchase and installation cost of the battery solution, but it is better to also consider any expected maintenance costs over its life (maybe a replacement charger/inverter), the cost of the money you have spent (lost interest or maybe the possible return from using it for something else like a better car) and the fact that every year battery solutions seem to be getting better/cheaper.

NugentS' calculations seem to be working for him as he expects to completely discharge his batteries at least once a day, so over 12 years he will have stored/discharged at least 48MWh of energy. Most people would not get such a high level of use out of a system.



Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: jonsamcor on May 11, 2019, 05:54:32 AM
Thanks RIT ....
Basically crunch the numbers ......


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 11, 2019, 08:32:38 AM
Yeah - I think it works for me - but only just. Batteries are too expensive to cost in for most scenarios I think at the moment.

Sean


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: Scruff on May 11, 2019, 08:51:02 PM
Hands up anyone who has broken even or made a red cent from this progressive idea?
Factoring lifecycle hardware costs, installation costs, empirical efficiency, and deduct any grid related charges and low usage penalties?



Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: Scruff on May 11, 2019, 08:54:53 PM
Why are batteries better than direct drive?
Economically, electrically or ecologically?


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 24, 2019, 09:49:12 PM
Just to keep things updated.

Yesterday I (obviously not me) installed 14+kWh of batteries along with associated gubbins.
On a sample day of 1, with decent, but not great solar the numbers approximately match what I was expecting although I am still trying to figure out all the various numbers the monitoring screen gives. I did get a massive spike in consumption between 16:00 and 18:30 which I don't understand and need to see if if gets repeated. Given I was sat quietly reading a book this is something I need to look into if it keeps occurring.

As a side point - my Holmes unit (or is it a Wattson - whatever) is now essentially useless. as it doesn't seem to take into account batteries. There is a 3rd CT Clamp, but it doesn't seem to do anything at the moment

Can anyone suggest a cheap portable CT Clamp, that gives a reading in Watts / kW that I can use to spot measure items for power usage. I emphasize cheap as there seem to be plenty of serious expensive ones that do (yes I know I can calculate Watts, but I am lazy)

Sean


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: pantsmachine on May 25, 2019, 09:07:21 AM
Congratulations and welcome onboard the battery train. You should go through the process of working out what is drawing what watt and when. Easy enough with plug in meters and a bit of time. My charge controller graphs display battery state of charge (%), power charging and discharging from battery and finally power imported/exported to the grid in watts. It's a slightly different mindset with batteries.

https://www.amazon.co.uk/FLOUREON-Monitor-230V-250V-Consumption-Calculator/dp/B01DSQ30FO/ref=pd_aw_fbt_60_img_3/259-0587670-6139734?_encoding=UTF8&pd_rd_i=B01DSQ30FO&pd_rd_r=4f85cf6b-7ec4-11e9-8f6e-13e541aad909&pd_rd_w=3otvy&pd_rd_wg=WE1RS&pf_rd_p=2ef3f294-3d5d-499e-861c-c3dd12069854&pf_rd_r=DFWFF6MYQ03R4TKC79PR&psc=1&refRID=DFWFF6MYQ03R4TKC79PR


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 25, 2019, 04:44:32 PM
And last night it stopped working - I think the inverter has stopped talking to the batteries. An MCB tripped, I got woken up by lots of alarms from UPS's. Resetting the MCB stops the alarms - but doesn't let the batteries work. Looks like the comms have failed in some manner.

Yay. Super (etc). Stuff fails, as long as the supplier deals with it I am fine with it. I am a little more concerned that they haven't used a seperate MCB - but that can be dealt with.

Supplier is already on it - but its a bank holiday - which is just typical

Sigh

Sean



Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on May 25, 2019, 05:00:32 PM
https://www.amazon.co.uk/FLOUREON-Monitor-230V-250V-Consumption-Calculator/dp/B01DSQ30FO/ref=pd_aw_fbt_60_img_3/259-0587670-6139734?_encoding=UTF8&pd_rd_i=B01DSQ30FO&pd_rd_r=4f85cf6b-7ec4-11e9-8f6e-13e541aad909&pd_rd_w=3otvy&pd_rd_wg=WE1RS&pf_rd_p=2ef3f294-3d5d-499e-861c-c3dd12069854&pf_rd_r=DFWFF6MYQ03R4TKC79PR&psc=1&refRID=DFWFF6MYQ03R4TKC79PR

Not what I meant. I have plenty of those (or similar). I also have several smart sockets that do the same just remotely via an app (its just very easy to turn the socket off by mistake!!).
Something like: https://www.amazon.co.uk/TACKLIFE-Multimeter-Temperature-Continuity-Resistance/dp/B01MXGTGGC?ref_=fsclp_pl_dp_1
but which displays in Watts or kW rather than amps. I am assuming that Watts = Amps * Volts and I am only looking for an approximate value (so 1Amp = 1/4 kW ish) or am I missing something?

Sean


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: pantsmachine on May 25, 2019, 05:38:17 PM
https://forum.allaboutcircuits.com/threads/measuring-wattage-with-clamp-meter.120013/

I like simple stuff. Hence plug in at end of line.


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: NugentS on June 20, 2019, 05:16:26 PM
As an update.
Things are working largely as I expected - although the weather hasn't entirely cooperated.
 :fume
The replaced inverter is working just fine and hasn't gone pop like the first.
I am still exporting - but today (16:27) I have generated 13.6kWh and exported 0.7kWh (5%) with the batteries at 89%. I also import a bit during the day - but its bumps on a chart and expected
According to the charts I use about 40% of my battery charge between 18:00 and when I start charging overnight so as long as I have 50% at 18:00 I am OK. I also only charge to 90% giving PV an extra 10% of headroom to fill. Thinking of dropping this to 80% and hoping for sunshine
I have also reduced my baseload by 25% which has kinda bumblebeed my calculations a bit and means I need to adjust my max SoC overnight otherwise I export more than I need to. But this is going to be hard to calculate given the variable nature of PV. If I could predict a good summers day I could seriously reduce the starting SoC

Yesterdays chart, with really crappy PV was https://www.dropbox.com/s/ts3ocf4jyf39xp6/2019-06-20.jpg?dl=0 (https://www.dropbox.com/s/ts3ocf4jyf39xp6/2019-06-20.jpg?dl=0)

What I need now is a good summers day to see what the chart does - see how much I export, import and how the batteries react - but I only have 20:20 hindsight I am afraid

Sean

Also - the inverter comes with a number of metrics - does anyone know what they might mean?

Qac(Var) - shows zero all day?
Vepsr(V) - I think mains voltage - hovers around 240 all day +/- 1
Feps(Hz) - mains frequency - hovers around 50
Peps(W) - a consistent zero?
Seps(Va) - also zero?
pToGrid(W) - export to grid - spends most of its time at zero, with bumps during daylight when the batteries were at or just about 100%



Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: wookey on October 01, 2019, 03:35:50 AM
Why are batteries better than direct drive?
Economically, electrically or ecologically?

I think they make sense for the local DNO to flatten out loads from houses and supply from PV. For the individual they are useful if the supply is unreliable. I gather companies are now giving incentives for people to install them, presumably as virtual storage. It makes more sense to have bigger batts serving a few houses, than one in every house. I note that new-build being planned here intends to put in one batt per 2-3 houses (and no gas, so well done them).

I just had a chap from a local company come round and offer me a battery system, (which is why I'm doing a bit of research). They have got an awful lot cheaper in the last 3 or 4 years, but I'm not sure there is much sense in it beyond the above reasons.


Title: Re: Solar Battery, PV and Eco Rate Electrickery
Post by: Scruff on October 02, 2019, 11:41:22 AM
My biggest problem with them is the wholesale naivety that the datasheet figures will match the real world operational conditions and the head in the sand no need to measure it because "it's green" attitude.
Back-up batteries are standby offline.

No inverter, charger, battery, inverter, load configuration can offer as much power on the network as not having them. Simple maths, power conversion losses are a thing.
If the network caters for network storage the individuals can power share and reduce demand for dirty power.



No gas? What arrogance.  ::)
Fit gas with the option of not using it.  :fight
PV doesn't work in Winter. Batteries are a collector not a source.