Solar Battery, PV and Eco Rate Electrickery

[NugentS]

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

[pantsmachine]

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

[NugentS]

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

[NugentS]

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

[pantsmachine]

https://forum.allaboutcircuits.com/threads/measuring-wattage-with-clamp-meter.120013/

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

[NugentS]

As an update.
Things are working largely as I expected - although the weather hasn't entirely cooperated.
 
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

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%

[wookey]

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.

[Scruff]

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.  
PV doesn't work in Winter. Batteries are a collector not a source.