#1 April 20, 2017 08:40:15

TerFar
Registered: 2014-06-21
Posts: 61
Reputation: +  0  -
Profile   Send e-mail  

Battery storage first impressions

WendyNorthrop
Regarding…others have previously asked if there is any facility to top up the batteries from off-peak power. I asked exactly the same question prior to purchase and was told well yes, but currently no in the UK. There is certainly a setting in the configuration that allows you to set 2 “charge from grid” periods. Both of these are shown enabled on my system but it doesn't actually do it. It was explained to me the reason is that SolaX think it would be frowned upon to buy power at off-peak (6p) and then effectively sell it back as generated power at your FIT rate as your battery discharges … I am not sure why SolaX think it would be frowned upon… Look at FFestiniog and Cruachan pumped-storage facilities. For over 50 years they have been using National Grid supplied off-peak power to pump water into reservoirs and on-demand they sell generated electricity back to the grid at a higher price. How is what you and others want to do different?

Thanks for the information. But what a let down: the facility is there but it is deliberately disabled. I'm quite sure that disabling it must be illegal. You pay for your off-peak electricity: where does it say that you cannot use it for recharging batteries. Are all mobile users breaking the law? If anyone with off-peak electricity uses their power during low rate to charge batteries for use during peak times are they breaking the law? What about people recharging their electric cars at night? This cannot be right.

I seriously suggest that you contact them and demand that they re-enable this feature or you will report them to Ofgem for obstructing your electricity usage. If you don't get satisfaction, you could even make a close calculation as to how much you'd save over a year, multiply it by 10 (the estimated life of the battery storage) and take them to small claims court.

Offline

#2 April 20, 2017 09:04:56

TerFar
Registered: 2014-06-21
Posts: 61
Reputation: +  0  -
Profile   Send e-mail  

Battery storage first impressions

dwilliams

Your reasoning doesn't make sense. Both with and without storage, only excess (solar) generated power is released to the grid. With battery storage, the excess generated power is used firstly to recharge the batteries, then once the batteries are fully charged, the (solar) excess goes into the grid.

As the system currently stands, most of us don't have an export meter, only a generation meter, so payment is based on an assumption that 50% of generated power is exported. Possessing a battery store makes no difference: you still get paid for 50% of the (solar) power you generate.

Now if you use off-peak electricity to charge up the batteries in the dark winter months, it doesn't make an iota of difference to excess electricity fed into the grid because there is very little solar electricity generated that is usually used either used by the home or trickles into the battery store. And the batter power is never fed into the grid anyway.

So where do you get the idea that your buying electricity at 6p and selling it back at 15p (in my case)? You're not. You never feed power from your batteries into the grid, so it can never happen. And the FiT licencee will never know because you cannot generate more electricity than the sun allows. The battery store is totally irrelevant.

Offline

#3 April 20, 2017 10:02:00

dwilliams
Registered: 2011-11-09
Posts: 71
Reputation: +  0  -
Profile   Send e-mail  

Battery storage first impressions

Hi Wendy, I have been very careful to stress that my comments apply to our SolaX system. What I have discovered in the past year is that not all battery storage systems work the same.

The SolaX system, as it works today, every millisecond it is working out how much demand there is in the house, how much the PV is generating and sharing it between powering the house and charging the battery. If we are not using much in the house, say because we are out, then the battery will charge much faster (from 20% up to 100% by lunch time in the recent sunny weather here in the south). When and only when the battery is 100% and solar PV exceeds demand in the house does any energy get fed into the grid through the generation meter … and after that, when the battery discharges.

As the sun sets the battery gradually increases the amount of power it discharges to support demand in the house. When it's finally dark the battery is supplying 100% of demand until it reaches the 20% cut off threshold maintained for EPS power cut mode. Of course if during the evening demand in the house temporarily exceeds the ability of the battery to provide all the power e.g. we put the kettle on, the system will import what it needs from the grid to top up … it's all very dynamic.

You say “And the battery power is never fed into the grid anyway”. Strictly speaking that statement is true, but it is the power being discharged from the battery that goes through our generation meter. I will post a graph from our Geo Chorus PV monitor that illustrates how our “PV generation” goes on well after dark but really that's as the battery discharges. NB our “battery” is 3 x 2.4kWh physical batteries in parallel.

Offline

#4 April 20, 2017 11:28:33

TerFar
Registered: 2014-06-21
Posts: 61
Reputation: +  0  -
Profile   Send e-mail  

Battery storage first impressions

“but it is the power being discharged from the battery that goes through our generation meter.”

I find this extraordinary and I would say that the installer has got the wiring wrong. The generation meter should ONLY record the solar power generated.

All payments are based on what the solar panels generate - what the generation meter should display. You then get an index linked generation payment for every kWh the panels generate. Plus you receive an export tariff which is usually deemed as 50% of what you generate. It is unnecessary (and unusual) to have an export meter, which is why the deemed rate is paid based on generation. You don't need an export meter until the system is rated over 30kWp.

The battery output should not go through the generation meter. If it does, it has been incorrectly wired. The generation meter should be wired after the solar inverter before it joins the house wiring junction point. That way, it only records the solar power generated. Whether you have a battery store is irrelevant to the generation and export payments.

Offline

#5 April 20, 2017 11:58:59

dwilliams
Registered: 2011-11-09
Posts: 71
Reputation: +  0  -
Profile   Send e-mail  

Battery storage first impressions

Hi TerFar, my apologies for addressing my earlier response to Wendy and I blame the small screen on an iPhone! Regarding your latest response to my further explanation I don't know what I can say. I suppose I might rephrase it and say “but it is the power being discharged from the battery that is being recorded on our generation meter.”

I can assure you that is how it was explained to me and how it works in practice. When I went to our Geo Chorus PV monitor, which pre-dates the battery installation, I find it went off the internet 2 days ago. I have re-established connection and the data for the graphs is now flowing again. Tomorrow morning I should be able to show you how “generation” goes on even during the hours of darkness, ceasing either when the battery capacity reaches 20% or the time reaches 0130 hours in the morning. This is how I have configured our system so that the battery does not discharge when we are in the Economy 7 night period (presently 0130 > 0830 here). Our battery currently shows 78% so there's a good chance we will get to 100% about 1500 hours.

Offline

#6 April 21, 2017 11:29:21

dwilliams
Registered: 2011-11-09
Posts: 71
Reputation: +  0  -
Profile   Send e-mail  

Battery storage first impressions



TerFar
I find this extraordinary and I would say that the installer has got the wiring wrong. The generation meter should ONLY record the solar power generated.All payments are based on what the solar panels generate - what the generation meter should display … The battery output should not go through the generation meter. If it does, it has been incorrectly wired. The generation meter should be wired after the solar inverter before it joins the house wiring junction point. That way, it only records the solar power generated. Whether you have a battery store is irrelevant to the generation and export payments.

What you describe is probably true for many of the battery storage systems now coming to the market, especially those which are aimed as a retrofit to an existing PV system i.e. keeping the original panels and inverter. Our system only uses the original solar panels which are connected to the SolaX X-Hybrid device.

To be fair, SolaX do describe their system as “More than just an inverter, the innovative X-Hybrid is an intelligent energy management system that stores surplus energy in batteries for later use.” The Solax design approach is not wrong, nor has it been wired incorrectly, but it's certainly different. That said, the generation meter IS wired after the inverter (X-Hybrid) before it joins the house wiring.

I am finding it very difficult to describe how such an integrated and dynamic system works so I will focus on the specific area of the generation meter which is at the nub of this discussion.

1. During the daylight hours PV generated energy that the X-Hybrid directs to the house at any moment in time IS recorded on the generation meter.

2. During the daylight hours PV generated energy that the X-Hybrid directs to charge the battery at any moment in time IS NOT recorded on the generation meter. It is so important to appreciate that energy directed to charge the battery this very second may be directed to the power the house the very next second and in those circumstances 1. above applies.

3. During the hours of darkness ENERGY in the battery (so long as capacity exceeds 20% configurable) is directed to the house by the X-Hybrid and IS recorded on the generation meter.

Note - in point 3 I just use the term ENERGY. It is highly likely to have been generated from the PV so is eligible for the FIT. However, if you have charged the battery from the grid it will still be counted hence my comment import for 7p, export as FIT 49p.

I think the bottom line at the moment is that anyone who wants to charge from the grid rather than use their PV intelligently should steer clear of the SolaX system. That said, I know they & the supplier are aware of this debate so there MAY be firmware/hardware changes in the future so that only PV generated energy clocks up on the generation meter.

I will just upload the Geo Chorus PV monitor graphic showing how our PV generated energy is being used to power the house long after sunset as it's discharged from the battery. SolaX call this “deferred solar power” as it goes through the generation meter. As I said before, our system is configured not to discharge while our electricity is on Eco 7 night rate.

Attachments:
attachment cpv.jpg (113.8 KB)

Offline

#7 April 21, 2017 11:34:17

dwilliams
Registered: 2011-11-09
Posts: 71
Reputation: +  0  -
Profile   Send e-mail  

Battery storage first impressions

WendyNorthrop
Hi, Please can you state how much the total installation cost to buy and install and how much are the additional battery units?Wendy

As at May 2016 full system (2 x 2.4 batteries) and installation was £5,300. Extra battery added Nov 2016 £1291.50. I have asked for updated costs and await a reply.

Offline

#8 April 21, 2017 13:19:25

dwilliams
Registered: 2011-11-09
Posts: 71
Reputation: +  0  -
Profile   Send e-mail  

Battery storage first impressions

TerFar
Thanks for the information. But what a let down: the facility is there but it is deliberately disabled.

Hi TerFar, it's only disabled by default when installed. Using the SolaX iOS (or Android) app you can enable and set one or two time periods to charge from the grid. As mentioned back nearer the start of this thread I have tested it once and it works. It took about 2 hours to fully charge the battery from 20% to 100%. At that time my “battery” was 2 x 2.4kWh physical batteries.

I have uploaded a screenshot from the app. N.B. this particular setting is only available locally when the iOS device is connected directly to the X-Hybrid via it's own WIFI signal.

Attachments:
attachment solax app.jpg (111.2 KB)

Offline

#9 April 21, 2017 13:36:00

dwilliams
Registered: 2011-11-09
Posts: 71
Reputation: +  0  -
Profile   Send e-mail  

Battery storage first impressions

TerFar
I find this extraordinary and I would say that the installer has got the wiring wrong. The generation meter should ONLY record the solar power generated … The battery output should not go through the generation meter. If it does, it has been incorrectly wired. The generation meter should be wired after the solar inverter before it joins the house wiring junction point. That way, it only records the solar power generated. Whether you have a battery store is irrelevant to the generation and export payments.

Further to my post 11:29:21 today which has a screenshot cpv.jpg attached. I have two PV systems located within half a mile of one another. Both face south/south west without shading so experience 99% the same weather conditions etc.

For comparison I have uploaded another screenshot spv.jpg covering exactly the same period from my second system. This one does not have battery storage/SolaX system attached. You can see that it's the more conventional arc on a fine sunny day starting PV generation at sunrise through to sunset.

Attachments:
attachment spv.jpg (113.6 KB)

Offline

#10 April 21, 2017 15:14:34

WendyNorthrop
Registered: 2012-04-23
Posts: 14
Reputation: +  0  -
Profile   Send e-mail  

Battery storage first impressions

As at May 2016 full system (2 x 2.4 batteries) and installation was £5,300. Extra battery added Nov 2016 £1291.50. I have asked for updated costs and await a reply.

Thanks for the information…

Offline

Board footer

Moderator control

Powered by DjangoBB

Lo-Fi Version