Home Battery Charging

[Mach13]

I'm new to solar and Battery stuff. and am considering having 4KW panels with a SolaX 5.8KW battery and a 3.6kw inverter

One of the aims is to use the Octopus Go rate that i have to charge the battery overnight during winter.

I also have a hybrid car that uses a smart charger drawing max 3.6kwh that I intend to charge at the same time.

Q: Is the system likely to cope with them both charging at the same time or will I have to offset their charge times? or is there another tree i should be barking up?

Q: is it possible/usual to pre-set depletion and charge amounts .ie keeping the battery between 20-80 %?

Q: anything else i should be considering before I buy?

Thoughts appreciated

 

[johnb2713]

I'm new to solar and Battery stuff. and am considering having 4KW panels with a SolaX 5.8KW battery and a 3.6kw inverter

Welcome aboard

One of the aims is to use the Octopus Go rate that i have to charge the battery overnight during winter.

I do the same, both winter and summer though!

I also have a hybrid car that uses a smart charger drawing max 3.6kwh that I intend to charge at the same time.

Does it have a dedicated wall box, is it solar compatible eg like ZAPPI?

Q: Is the system likely to cope with them both charging at the same time or will I have to offset their charge times? or is there another tree i should be barking up?

The 3.6kWh inverter is it's output, potentially your car could consume all of it. The other side of the inverter is the charge controller which will take the energy from the solar PV use what is required to feed the output and any surplus fed into the battery. In my view the inverter size is too small, 6kW would be more appropriate, with the car on charge, switch the kettle on and you've exceeded 3.6kW with ease.

Q: is it possible/usual to pre-set depletion and charge amounts .ie keeping the battery between 20-80 %?

In my inverter yes, set max and min levels, I have mine set to 10 & 90%

Q: anything else i should be considering before I buy?

Double the size of the inverter, the contractor will need to make application to DNO but it will be worth it. If you dont, as soon as you hit 3.6kW consumption it will start importing from the grid.[/QUOTE][/QUOTE]

 

[Mach13]

Wow firstly thanks for the way you answer Johnb2713.. Really helpful and concise

Inverter size.. useful food for thought..

My EV Charger is a Sync EV, which contrary to what i'd thought does not work with solar the way the new Zappi V2 does.... ie no dynamic throttling... as its only been installed a year i'm loathed to chuck it for now.. in the hope that SNYC EV come up with something to compete with the Zappi in time

But my SyncEv can be throttled down manually to 1Kwh for charging.. As my car is a hybrid (16kw battery) my thinking is I could put it on that to trickle charge it during the day.. our background usage daytime is very low it usually bimbles around 113 to 213w.


So i guess key to functionality is being able to adjust storage settings/parameters.

the two batteries we have on offer are solaX and Giv energy.. any idea if these offer app functionality that id need?

any knowledge on these?

 

[johnb2713]

Wow firstly thanks for the way you answer Johnb2713.. Really helpful and concise

Youre very welcome.

Inverter size.. useful food for thought..

It seems a lot of installers opt for 3.6 kW to avoid discussions with the DNO. I've monitored my system very closely and I'm just starting to build another battery pack (14kWh) and add another inverter (5kW) this is to keep me away from peak rate power in the winter.

My EV Charger is a Sync EV, which contrary to what i'd thought does not work with solar the way the new Zappi V2 does.... ie no dynamic throttling... as its only been installed a year i'm loathed to chuck it for now.. in the hope that SNYC EV come up with something to compete with the Zappi in time

It wouldnt be too difficult to make an add on unit that adjusts the output relevant to surplus Solar PV. They control how wide the pulse is on a control line (pilot line) so the EV knows how much current it can take. As the pulse width goes down they take less power. The ZAPPI has a sensor on the mains supply, when to it sees energy being exported it adjusts the signal so the car will
start charging / adjust the charge rate to suit.

But my SyncEv can be throttled down manually to 1Kwh for charging.. As my car is a hybrid (16kw battery) my thinking is I could put it on that to trickle charge it during the day.. our background usage daytime is very low it usually bimbles around 113 to 213w.

Yes you do it manually just not very efficient.

So i guess key to functionality is being able to adjust storage settings/parameters.

Yes it is, have a look at home assistant, it's an open source project that integrates all sorts of equipment in the home, inverters and storage being one area, it is also free and runs on a raspberry Pie.

the two batteries we have on offer are solaX and Giv energy.. any idea if these offer app functionality that id need?
any knowledge on these?

Several people on here will be able to help with these. I personally have never used either on, my inverter / battery is Growatt, my new one has a Victron inverter and the battery I'm making.

 

[Mach13]

The 3.6kWh inverter is it's output, potentially your car could consume all of it. The other side of the inverter is the charge controller which will take the energy from the solar PV use what is required to feed the output and any surplus fed into the battery. In my view the inverter size is too small, 6kW would be more appropriate, with the car on charge, switch the kettle on and you've exceeded 3.6kW with ease.

I asked the salesperson about beefing up the inverter, and did my best to explain your comment... the response i got back was that the battery has an output of 5.2kw so it didn't matter its a hybrid converter if that makes a difference.. but then did say he would ask his tech team.. so will wait for that..

Am expecting the other quote in soon so will be interesting to see what they offer

Thanks again for you help

 

[binky]

I asked the salesperson about beefing up the inverter, and did my best to explain your comment... the response i got back was that the battery has an output of 5.2kw so it didn't matter its a hybrid converter if that makes a difference.. but then did say he would ask his tech team.. so will wait for that..

Am expecting the other quote in soon so will be interesting to see what they offer

Thanks again for you help

the man knows not of what he speaketh! Discharge from the battery will be controlled by the hybrid inverter. Most have a peak output higher than 3.6kw, but for very short periods of time, like seconds.

 

[johnb2713]

I asked the salesperson about beefing up the inverter, and did my best to explain your comment... the response i got back was that the battery has an output of 5.2kw so it didn't matter its a hybrid converter if that makes a difference.. but then did say he would ask his tech team.. so will wait for that..

How would we explain this in Yorkshire........... ******** LOL

For example, your 3.6kW inverter is doing it's stuff, the solar on the roof is supply 2.4 kW (its a nice day), and battery is full.

The washing machine is running taking a 2.2kW load, the missis is ironing taking a 900w load. The inverter is supply these loads totalling 3.1kW by taking the 2.4kW from the roof and 0.7 kW from the battery. All good. Then you switch a 2 kW kettle on, the invert ramps up to it's maximum of 3.6kW and the balance needed (1.5kW) is imported from the grid. If you'd had a 6 kW inverter, it would all been handled by the inverter / solar / battery.

There are obviously many other combinations that will exceed the maximum 3.6kW output - electric hob with 2 rings \ oven \ tumble drier etc.

The battery has a CAPACITY of 5.2kWh, hybrid inverter makes no difference (it can charge the battery from the grid or from solar).

Am expecting the other quote in soon so will be interesting to see what they offer
Thanks again for you help

Youre very welcome.

J

 

[Mach13]

lol thanks folks... will stick at it...

 

[Mach13]

I went with Solax in the end... 4Kw panels, Solax X1 5T Hybrid 5KW Inverter and 2 x Solax 5.6KW batteries. With an iBoost for heating hot water with excess energy.

working absolutely fine... Apps really useful, tho doesn't seem to show particularly accurate data.. tho i'm not too fussed about that.

I'm charging the batteries overnight and the solar tops things up during the day. so daytime (peak rate) grid draw is next to zero

One thing I'm bemused about if anyone has any experience of Solax Inverters

When the batteries are set to charge between 12:30 and 4:30 obviously the inverter draws from the grid until the charge period is released.. At 4:30am id expect the batteries to take up power delivery.. Which they do for the main part..

BUT I've noticed that whenever the home power draw is less than around 100watts the inverter allows this to come from the grid.. this is usually until we get up and start drawing more power (kettle etc..) at which the draws goes to battery... NB I'm not talking about intermittent grid draws.. i'm talking draws that can last for hours- albeit of around 70-80 watts .

Is this just just one of those anomalous things that inverter systems do.. or is there a setting somewhere that will resolve it so that it always draws from the battery no matter how small the draw is?

 

[arwooldridge]

I believe this is a combination of CT sensor accuracy and threshold set in the inverter which AFAIK is not adjustable. If they set the threshold too low CT errors (eg due to phase shift) could cause the inverter to misinterpret import for export or vice versa. Hence a common threshold is to set at 100watts or sometimes more.
For the technically minded there is an indirect way of adjusting the threshold by adding a bias current via an extra wire looped through the CT. This need not consume hardly any power if you first transform the voltage down say below 1 volt. You could use say two transformers in series giving say 0.6 volts output. better still use a toroidal transformer (eg https://www.rapidonline.com/vigortr...former-230v-single-primary-50va-0-12v-88-5192.) With a single or few turns of wire through the toroid. Careful choice of transformer output resistance and a small series resistor if necessary can give you the bias current you need ie 0- 0.4 amps. At a fraction of a Watt consumed (actually you have to add the power due to the leakage current of the first primary winding, but still less than a watt if you choose the right transformer)
Needless to say make it all safe in an enclosure and fully fused. Also avoid if any of this is unfamiliar territory!

 

[Mach13]

Clever stuff there 'arwooldridge'... So for the not so technically minded... It is what it is... a tolerance issue that may one day be resolved by some tried n tested technical wizardry from those that are indeed very 'familiar' with that kinda territory .

 

[johnb2713]

For the technically minded there is an indirect way of adjusting the threshold by adding a bias current via an extra wire looped through the CT.

I can see the issue when a CT approaches zero current, it's difficult to detect and interpret zero, noise margins become significant. In this application though the bias idea surely will just move the problem to another operating zone i.e. when the induced current from the meter tail is cancelled out by the induced current from the bias system, surely that will give the same noise / inaccurate operation?