Home Storage Battery

[Coulomb]

The problem with using the "amp clamp" version is that it does not take into account how much power the solar panels produce as far as i can see.

My understanding is that it's indirect. It assumes that any spare PV power is exported, so by ensuring that the exported power is zero or at least not negative (not importing), that it's making use of all available PV power.

For many systems, they use AC transfer (of PV power to loads) and it presumably works well. My system uses DC transfer, there is never exported power, so there is nowhere to put the clamp to make it work.

Perhaps a Harvi could be used perhaps with a modified sensor in my situation.

 

[hmadsen]

Yeah, i can see that.

I buy on 3 phases, but only sell on 1, so basically all i would need is one clamp, that would detect the flow of electricity on the one phase i sell to, and the smart meter on my solar system would adjust the charger indirectly because it adjusts the "output" on that one phase to whatever i buy combined on all 3 phases.

I would need to be able to adjust the zappi to do a max combined load of 3600 watt's as this is the most my solar panel can output to the grid because of the inverter.

 

[BarryH]

The problem with using the "amp clamp" version is that it does not take into account how much power the solar panels produce as far as i can see.

Also, my house has 3 phase power, and the smart meter will add the load on all 3 phases and then feed the same amount of power back into the grid to null out the buying of power.

I want to use only what is available up to 3600 watts but if the solar panels only make, lets say 2500 watt's and the house uses 1000 watts, i want it to charge at 1500 watts.

I know i am a bit particular, but the whole idea of solar panels and the electric car for me was to be able to charge the car, without paying anything as i fill it with my own solar power.

If you have 3 phase supply to the house do you also have a 3-phase PV inverter or just a single-phase PV inverter, and in that case, I assume you'll have had a single-phase, not 3 phase Zappi installed on that phase of your supply. But if everything is 3-phase doesn't the Zappi have a CT clamp on each of the phases?

 

[hmadsen]

If you have 3 phase supply to the house do you also have a 3-phase PV inverter or just a single-phase PV inverter, and in that case, I assume you'll have had a single-phase, not 3 phase Zappi installed on that phase of your supply. But if everything is 3-phase doesn't the Zappi have a CT clamp on each of the phases?

I have 3 phases in, all phases run through a smart-meter that was delivered with the solar system.

This smart device is summing up the combined use on all 3 phases and sending the power drawn figures, to the inverter.

The inverter will then send power out on the one phase to match the combined load.

If it can match the load, i pay nothing for the used power on any of the phases.

Basically it has a priority whenever it generates power. (Sun is shining on the solar panels)

First priority : Match whatever i use right now.

When i generate more power than is needed to meet the current used load, it will first take the excess energy and put it into the 6½ KWh Lithium battery, and when the battery is full, it will then sell the rest of the electricity to the grid.

The smart meter and inverter does all of the clever math and the company that i buy and sell electricity to and from, also has access to the numbers to be able to send me the bill for the electricity i used from the grid, and deduct whatever money i made from selling excess power to the grid.

My main concern is if the Zappi is able to detect how much power i sell, and only draw that.

If it will just see that i use 1000 watts and then it will take 2600 watts no matter what i am generating i risk that it will just suck power from the grid if my power generation is for example 2000 watts, and this is what i want to avoid as much as possible.

 

[BarryH]

I have 3 phases in, all phases run through a smart-meter that was delivered with the solar system.

This smart device is summing up the combined use on all 3 phases and sending the power drawn figures, to the inverter.

The inverter will then send power out on the one phase to match the combined load.

If it can match the load, i pay nothing for the used power on any of the phases.

Basically it has a priority whenever it generates power. (Sun is shining on the solar panels)

First priority : Match whatever i use right now.

When i generate more power than is needed to meet the current used load, it will first take the excess energy and put it into the 6½ KWh Lithium battery, and when the battery is full, it will then sell the rest of the electricity to the grid.

The smart meter and inverter does all of the clever math and the company that i buy and sell electricity to and from, also has access to the numbers to be able to send me the bill for the electricity i used from the grid, and deduct whatever money i made from selling excess power to the grid.

My main concern is if the Zappi is able to detect how much power i sell, and only draw that.

If it will just see that i use 1000 watts and then it will take 2600 watts no matter what i am generating i risk that it will just suck power from the grid if my power generation is for example 2000 watts, and this is what i want to avoid as much as possible.

My understanding is that the Zappi has 3 modes of operation and the mode you are interested in is the mode which monitors the connection to the grid and adapts the charge rate to correspond to the flow of excess power out to the Grid. This is what the CT clamp on the Grid connection is for. The CT senses current and direction of flow so as to minimise the out bound export flow buy using it to charge your EV. Now there is a case for not completely eliminating the export if the excess is below a certain amount and the Zappi stops the charge if it drops below a set point because the car charging circuits become less efficient the lower the charge rate. From memory it's something like 1.2 kW but you can override this down to about 300 watts but you have to be aware that at at that level most of the power is going into losses and it might be better to use excess below 1 kW just to heat domestic water with an Eddi which will integrate into the MyEnergi eco-system.

 

[Deleted member 2439]

My understanding is that the Zappi has 3 modes of operation and the mode you are interested in is the mode which monitors the connection to the grid and adapts the charge rate to correspond to the flow of excess power out to the Grid. This is what the CT clamp on the Grid connection is for. The CT senses current and direction of flow so as to minimise the out bound export flow buy using it to charge your EV. Now there is a case for not completely eliminating the export if the excess is below a certain amount and the Zappi stops the charge if it drops below a set point because the car charging circuits become less efficient the lower the charge rate. From memory it's something like 1.2 kW but you can override this down to about 300 watts but you have to be aware that at at that level most of the power is going into losses and it might be better to use excess below 1 kW just to heat domestic water with an Eddi which will integrate into the MyEnergi eco-system.

It’s actually 1.4kW. Why would “much go as losses” at low settings? Losses are a % of the power being transferred and not an absolute amount. Note that the balance charge of 300 watts. I’m intrigued by your assertion and would like to understand it further. I’ve quite happily charged a number of different EVs from our Zappi @ the 1.4 kW setting either taking available solar as the source, grid power or from the battery system which has been previously topped up with either solar or Octopus Go sourced energy. Seems a win-win to me as its a nice gentle activity going on in the background and leaving some capacity available for other things.

 

[BarryH]

It’s actually 1.4kW. Why would “much go as losses” at low settings? Losses are a % of the power being transferred and not an absolute amount. Note that the balance charge of 300 watts. I’m intrigued by your assertion and would like to understand it further. I’ve quite happily charged a number of different EVs from our Zappi @ the 1.4 kW setting either taking available solar as the source, grid power or from the battery system which has been previously topped up with either solar or Octopus Go sourced energy. Seems a win-win to me as its a nice gentle activity going on in the background and leaving some capacity available for other things.

Thank you for the correction on the 1.4 kW threshold, I don't own a Zappi currently myself but plan to replace my Pod point with one after I have my PV and Storage installed in about 5 weeks' time. Yes, the Balance charge certainly does draw approximately 300 watts, but that doesn't mean that anything like that amount goes into the vehicle battery. However, it isn't correct to say that "losses are a % of the power being transferred". The losses are not linear and have a number of components to them. There is certainly a "proportional" percentage of the power being transferred and that is the majority loss through the onboard charger and cables at normal rates of charge, but the charger also has a power overhead to run the components which is linear and an efficiency curve which falls off at less optimal charge rates. (It has been reported on this forum in another thread if memory serves me that there is a lower charger efficiency at 2.4 kW on a 10 Amp Granny Charger [ie Portable EVSE] although I've not tried to reproduce those comments.) About 2 years ago When I was shopping for a home charging solution about 2 years ago, I spoke with a software developer working on software development for Home EVSE and Vehicle to Grid development and they told me that they thought the reason that MyEnergi had set a 1.4 kW cutoff was that below that level a person would probably find it more beneficial to use their Eddi to heat domestic hot water since a hot water heater can still utilise those lower power levels.

I believe Nigel, on his EV Puzzle YouTube channel when he had his Hyundai Kona did a Vlog on setting his Zappi to share at lower rates and acknowledged that the efficiency would be rubbish but he'd rather get some charge than none.

 

[Deleted member 7171]

 

[Rob Smart]

When the Zappi is in "ECO Plus" mode it can do what you want by using the surplus power after the house has consumed all it wants, but with with one caveat:

In my Zappi's manual it states that "the EV charging standard" dies not allow chareging below 1.4 kW.

So in your "wanted" example, if the PV is producing 2500 watts and the house is using 1000 watts, the EV would charge with 1500 watts. But if a cloud comes over and the solar only produces 2300 watts, charging would be paused until the cloud had passed.

To be able to do this, the Zappi needs to sense for itself what the solar is producing in real-time, and what the house is using, so really does need the CT clamps. I have a "Harvi" unit which is placed close to the Distribution board so that the CT clamps can have short leads to it and not look messy, and then it communicates to the Zappi hub wirelessly.

This all works very well. Hope this helps.

 

[Coulomb]

To be able to do this, the Zappi needs to sense for itself what the solar is producing in real-time, and what the house is using, so really does need the CT clamps.

My understanding is that it can do it with one clamp, on the export current. As long as the house is exporting more than 6A, the Zappi can charge the car with that much current, and not cause any import.

So I don't understand why the Harvi is ever needed. I assume that there must be some cases, perhaps when you have three phase power.

Edit: Ah, I see a problem with the above. The Zappi would have to take into account its own usage. So the criterion would be charge when exported current plus the Zappi's current is greater or equal to 6A. So if exporting 1.5A when charging at 6A, it's safe to go to 7A. But then while charging at 7A if the exported current falls below -1A (importing 1A or more briefly) , it has to pause. But I'm pretty sure that it can do this.

 

[hmadsen]

In the end i ended up buying the cheapest charger i could find, this is also adjustable from 6A to 16A.

I found that the added cost of the automatic ones were probably to high for me to ever recover the extra cost.

Yesterday, i charged the car @13A, adding 15 KWh to the car battery and according to the inverter app, i only sold 2 Kwh to the grid.

If i would only have been able to gain 2 KWh a day, i would never recover the extra 100s of £ for the fancy inverter...And the extra installation costs.

 

[biffo]

In the end i ended up buying the cheapest charger i could find, this is also adjustable from 6A to 16A.

I found that the added cost of the automatic ones were probably to high for me to ever recover the extra cost.

Yesterday, i charged the car @13A, adding 15 KWh to the car battery and according to the inverter app, i only sold 2 Kwh to the grid.

If i would only have been able to gain 2 KWh a day, i would never recover the extra 100s of £ for the fancy inverter...And the extra installation costs.

This is a fair point - the variety of options are needed as there is no ‘one size fits all’ solution. There’s no denying that a smart 32A charger offers the best speeds and flexibility - but only if you need, want or can justify it. Otherwise, it’s spending money unnecessarily.

 

[hmadsen]

This is a fair point - the variety of options are needed as there is no ‘one size fits all’ solution. There’s no denying that a smart 32A charger offers the best speeds and flexibility - but only if you need, want or can justify it. Otherwise, it’s spending money unnecessarily.

Absolutely.

Now i charge the car at max 13A, due to the solar inverter, the seller sadly sold me one that in my opinition is a little to small.

But never mind, on a good sunny day i can add 20-25% SOT on the car, without spending a dime.

We will make it so, that on sunny work days, the washing machine, dryer and dishwasher will be started, staggered while we are at work, they will do what they do when we are away, and when the car gets back to our driveway, i will plug it in, if its sunny.

A normal day, the car does about 20 miles plus a bit of shopping, so i will probably be able to keep it pretty much topped up, and if there is a cloudy day, i can just opt to not plug it in, and wait until another day, where the sun is out.

 

[BarryH]

In the end i ended up buying the cheapest charger i could find, this is also adjustable from 6A to 16A.

I found that the added cost of the automatic ones were probably to high for me to ever recover the extra cost.

Yesterday, i charged the car @13A, adding 15 KWh to the car battery and according to the inverter app, i only sold 2 Kwh to the grid.

If i would only have been able to gain 2 KWh a day, i would never recover the extra 100s of £ for the fancy inverter...And the extra installation costs.

It's a good decision and should be driven by what your objective is. Is it to minimise your Costs? Minimise your Export? Minimise your Carbon Footprint? or simply Sett-up and forget? the solution you choose will be different in each case. Your solutions cost-effective, will need a lot of monitoring and manual adjustment throughout the year the charge rate for optimum balance between Charging EV from Solar PV, Exporting to the Grid and Importing to Charge the EV. But hey if you fancy a bit of Hacking, then if the EVSE is a cheap one it may be worth Hacking it to automate the charge rate

 

[Cowton jb]

Another non car question.

Does anyone have solar panels and a home storage battery?.

I am thinking of investing 4.5k in a GivEnergy 8kw system linked to solar in order to save on bills.

Does anyone have any experience on if savings are possible and how much bills can be reduced by.

Many thanks.

Hi. Yes I have ordered a 8.2Kwh Givenergy battery with solar but be warned that supply issues are horrendous, my order was placed last June, I'm still waiting. Givenergy have discontinued that version in favour of a new 9.3kwh model, but also not available immediately. My installer is now offering other battery alternatives, Sofar,Growatt, but unsure as to their quality.
Any advice greatly appreciated. Jon

 

[Cowton jb]

Perfect exactly what I was hoping someone would reply with. Thank you.

Hi Chris, I have ordered a battery solar setup from Deege but have been waiting almost a year since ordering due to Givenergy supply issues, according to Deege. I hope that they are a genuine trustworthy installer from your experience.
Thanks Jon

 

[AussiePete]

Absolutely.

Now i charge the car at max 13A, due to the solar inverter, the seller sadly sold me one that in my opinition is a little to small.

But never mind, on a good sunny day i can add 20-25% SOT on the car, without spending a dime.

We will make it so, that on sunny work days, the washing machine, dryer and dishwasher will be started, staggered while we are at work, they will do what they do when we are away, and when the car gets back to our driveway, i will plug it in, if its sunny.

A normal day, the car does about 20 miles plus a bit of shopping, so i will probably be able to keep it pretty much topped up, and if there is a cloudy day, i can just opt to not plug it in, and wait until another day, where the sun is out.

Do you have a battery? if so you should find that the battery acts as a buffer for when you’re charging. I do this with the standard granny charger, knowing when the sun is out it will be fed direct from solar, but should a cloud pass over the battery kicks in and covers the charge instead of drawing from the grid. On a good day the battery then charges back up when the sun comes back out. No smart solar charger needed

 

[hmadsen]

Do you have a battery? if so you should find that the battery acts as a buffer for when you’re charging. I do this with the standard granny charger, knowing when the sun is out it will be fed direct from solar, but should a cloud pass over the battery kicks in and covers the charge instead of drawing from the grid. On a good day the battery then charges back up when the sun comes back out. No smart solar charger needed

Yes yes, i have a 6½ KWh battery.

The panels are rated at 7200 Wh, but the inverter can only deliver 3600 Wh to the grid, but if the panels generate more power than that, it can also deliver up to 3600 wh to the battery charger.

So, what is most effective is to use as much of the power i generate up to 3600 Wh as this will slow down the charging of the battery and as long as i can do this, i use 100% of what is generated.

When the battery gets full, the production drops to 3600 Wh

But yes, yesterday it was a day of sun and clouds and the battery smoothed everything out, at one point the battery dipped as low as 91% SOT, but then the sun came out, and it promptly went to 100% again.

This morning i had to run the dishwasher as the battery was still at 37% when the sun came up, there is no need to start the day of with a 1/3 full battery

 

[hmadsen]

It's a good decision and should be driven by what your objective is. Is it to minimise your Costs? Minimise your Export? Minimise your Carbon Footprint? or simply Sett-up and forget? the solution you choose will be different in each case. Your solutions cost-effective, will need a lot of monitoring and manual adjustment throughout the year the charge rate for optimum balance between Charging EV from Solar PV, Exporting to the Grid and Importing to Charge the EV. But hey if you fancy a bit of Hacking, then if the EVSE is a cheap one it may be worth Hacking it to automate the charge rate

My goal is to save money. In Denmark, today, if you buy solar, there is no incentive programs, so i only get very little for every KWh i sell so every KWh i can use myself to run my house (Washing machine, clothes dryer and dishwasher running a LOT in a house of 5 people) and charge the car i will use.

The Carbon footprint i don't look at, so much, but i guess that if i use my own solar power to run the house, the washers and dryers, and charge my car, i will have lowered out carbon footprint, compared to before where we drove a diesel car, and bought all of our electricity.

 

[BarryH]

Hi. Yes I have ordered a 8.2Kwh Givenergy battery with solar but be warned that supply issues are horrendous, my order was placed last June, I'm still waiting. Givenergy have discontinued that version in favour of a new 9.3kwh model, but also not available immediately. My installer is now offering other battery alternatives, Sofar,Growatt, but unsure as to their quality.
Any advice greatly appreciated. Jon

I'd considered the GivEnergy but decided not to order on two grounds:
1, The GivEnergy system seems don't react very quickly to intermittent loads in particular being slow to switch from charging mode to Discarging mode meaning that as you switch large loads on and off ie 1 kW plus such as kettle, microwave toaster all of which you'll use multiple times a day and at first you'll be drawing from the Grid not your battery then when loads go off the GivEnergy battery will continue discharging and you'll then be exporting. Nigel on his EV Puzzel YouTube channel calculated that each day he got an excess of ½ kWh unnecessary Grid usage at Day Time Peak rate followed by ½ kWh unnecessary excess Export at a Low Export rate.
2: GivEnergy availability of key components meaning it could be 9 months before I would have a completed system.

I then looked for an alternative that had a rapid response time, and multiple international sourcing, available now, expandable and supports both Octopus Go now and was Agile Ready for when that becomes available/is practicable.

Moixa system (available as 2.4, 7.2 and 9.6 kWh) uses Victron Inverters and Pylontech batteries (for the 7.2 & 9.6 kWh systems) and a brilliant control AI to tie it all together. Ticked all but one of the boxes. The capacity box since although the 7.2 could expand to 9.6 kWh (which ought to serve most homes' needs) that is it! The Moixa solution is a package bundle not mix and match even though the Victron and Pylontech boxes are both standard kit. Oh and another thing the Charge Rate at 2 kW that is adequate to charge the 9.6 kWh Pylontech batteries overnight on Octopus Go would force Grid Export during a sunny day with 3 kW PV or more.

LuxPower looked like a good alternative. Very configurable, supporting lots of different 3rd party batteries (like Victron) and could be either in Hybrid (Solar PV & Battery Controller) Invert/charger. The Web-based user interface is excellent and Works with both Agile and Go. In fact, it is the most flexible and intuitive interface of any I've seen and I love the way you can tell it to find and charge only at 'x' number of cheapest half-hour-slots or to charge whenever the electricity price per kWh falls below a price you set. Commonly supplied with Pylontech or UHome batteries expandable up to 8 batteries of 2.4 kWh which is 19.2 kWh. Also, the Squirrel Pod variant can be used without PV charging solely off cheap rate overnight rate electrons and scaled up linking multiple Squirrel Pods with one acting in the lead role and the others synchronising charge and discharge with it. LuxPower is a very attractive alternative and I was offered installation by a local supplier from stock within 3 to 4 weeks.

However, the option I have gone for is Fox-ESS (Hybrid) with 7.8 kWh of Fox High-Voltage Battery Storage. Reasons are that it is 1, Certified "Works with Agile" 2, the whole system is from the one major industrial company, 3, there aren't supply issues, 4, the battery is a High Voltage battery (unlike the other parallel 48V battery solutions above) Fox-ESS connect the batteries in series so that they charge and discharge more efficiently. 5, the nominal 3.6 kW Inverter can deliver up to 5 kW peak instantaneously for several minutes which means you won't keep drawing from the Grid every time you flick on the kettle and toaster together or whatever. 6, The battery is a modular design and additional 2.6 kWh modules can easily be added finally 7, the supplying company is a reputable nationwide company that was very professional and responsive adapting their solution to my needs.