#1 Aug. 1, 2016 19:52:18

AndyT
Registered: 2015-05-28
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Battery storage first impressions

Hi there, I have not seen Heat Batteries mentioned, so please excuse me if I do.
I was fortunate enough to become a trialist of the SunampPV and it was fitted in March 2015.

This is a direct link http://wattson.energyhive.com/dashboard/AndyT
You can select views by day month or year and how much was being exported before the SunampPV was fitted.

Storing excess generation in phase change materials (PCM) a salt solution as latent heat, the SunampPV preheats the cold supply to the combi boiler. It's fair to say been working very well.

When I was made redundant in May last year I decided to ask Sunamp if they had any vacancies, and they took me on. Since then I increased the size of the heat battery from 5kWh to 10kWh.

If anyone would like some non-sales information on this technology I would be pleased to help.

Kind regards
AndyT

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#2 Jan. 31, 2017 22:36:22

TerFar
Registered: 2014-06-21
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Battery storage first impressions

morrisok
Hi,The android app I found called oxley solar, reads the temp on the sma inverters, mine has been above 50 degrees for the last few days, i don't know if that's ambient but even so, it must have an impact. I read something recently that it's not really the case about short cable runs as long as it's less than 15 or 20m.I've got quite a lot of background usage but am not using as much as 600w/h. You might want to look into how that's split up.

I'm a bit late reading this interesting thread. I'd like to comment on cable length. Cable length is exceedingly important for low voltage, dc power when current is very high. For a 220v ac power system, you can easily compensate for a longer run by using thicker cable. Short runs are fine using standard 2.5mm ring mains cable: for longer runs, use 4mm or possibly 6mm cable instead.

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#3 Jan. 31, 2017 22:45:05

TerFar
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Battery storage first impressions

gevans
My 4Kwh PV system was installed in July 2011 and has run unattended since then and I'm quite happy with its output and the FIT collected.I have been considering the possibility of battery backup but I'm unsure how to measure my base load to see whether it would make economic sense. I realise that the answer is probably very simple but as a “Plug-and-Play” PV user, I should welcome any suggestions here.Secondly, rechargeable Lithium batteries have a typical advertised life of 1,000 cycles (about 3 years with daily charge/discharge cycles). Can you tell me what evidence is there that Lithium batteries for PV system backup have a longer lifetime than this ?

The life of Li-ion batteries is strongly affected by the rate of charge/discharge. Charge is usually limited by the solar array, so a maximum of 4kW (~17A). Discharge depends on your household, but you can see it is easy to demand much more than 4kW.

Although Lithium batteries arrays are fully capable of meeting this demand, it does shorten the life of the batteries considerably. So all the latest systems are usually at least double the required size, which reduces the discharge rate and extends battery life. The newest systems suggest that the batteries may last 10 years. Of course, only time will tell if this is true.

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#4 Jan. 31, 2017 22:57:33

TerFar
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Battery storage first impressions

dwilliams
For most days over the first week we have not had ideal generation weather. Apart from one mainly rainy day we have had cloudy starts, lots of high fair weather cloud and a few short but intense periods of sunshine. Even so, performance seems to be getting better. Charging seems to be quicker and the battery is lasting longer. Maybe Lithium batteries need time to condition?Anyway, last evening the battery topped out at 96% and for the first time has continued to provide power until 0225 this morning. A somewhat odd (in my opinion) feature of this system is how it “defers” the generation. I expect many of you will be able to look at the weather conditions at any moment of time and make a good guess about how much your system is generating. From the very first day I noticed that when I would have thought the system would be generating, say, 1700w the SolaX system showed it to be about 700w. When the sun finally set I had clocked up a rather disappointing 8-9 Kwh when I might have previously expected 15-16Kwh. However, by the next morning my generation meter had caught up and all was well. This is because the “missing” generation is recorded later as the battery is discharged. If you have a look at the attached screenshot from today you will see on the top graph how the battery is finally exhausted about 0225 hours (2). Although the sun set many hour earlier you can see from the bottom graph how the Yield is still running high past midnight, tapering down to cease as the battery becomes exhausted. I have absolutely no idea why there appears to be a sudden demand as shown at (1).Kevin and 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 … because of the deferred generation feature. However, it seems that the same question is being asked by others, and it is not an unreasonable requirement in the winter when sun is in short supply. It is my understanding that they are “working on it”. While researching this prior to purchase I came across 2 documents, one from Parliament and another from OFGEM which seems to see the option to “time-shift” your use of power as being something to be encouraged in the future. I will upload those documents for others to see.

What I would like to see is some intelligence that is able to monitor and predict power requirements/weather so that during periods of poor generation, off peak (Eco 7) electricity is used to charge low batteries at night for use during peak times of the day.

So in the summer, the solar power runs the house during the peak times of the day, the excess being used to charge the batteries (and any excess to heat your water).

In the winter, the batteries power the house during peak hours and are recharged during the night on cheap off peak rate.

Any generation you're fortunate to get in the depth of winter can be used to heat your water.

That seems to me to be a win/win situation. Your batteries provide power during peak grid demand and are recharged in grid off-peak demand times. This saves money and helps keep the peak demands lower.

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#5 March 31, 2017 17:17:20

TAGWARE
Registered: 2014-08-19
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Battery storage first impressions

Hi

Thanks for sharing your experience.

Just one question.

What amount of PV do you currently have on the roof? 3-4kW?

Thanks.

Tagware

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#6 March 31, 2017 18:28:59

dwilliams
Registered: 2011-11-09
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Battery storage first impressions

TAGWARE
HiThanks for sharing your experience.Just one question. What amount of PV do you currently have on the roof? 3-4kW?Thanks.Tagware

Hi, 3kWh (12 panels) facing a couple of degrees off due South & no shading. Since my last post I have added another battery so now 7.2kWh (3 x 2.4). Even this early in the year they have charged to 100% several times by early afternoon and kept the house powered through the evening and into the Economy 7 off-peak period, at which time I have configured the system to stop discharging. When we went back to peak rate at 0830 the battery still had 29% charge giving it a good start to reach 100% again. I am seriously considering going for a 4th battery, which means a second cabinet too, but our system will certainly be able to fill them all during the coming months and into the Autumn. Of course Winter is a different matter but they still get enough charge to support the underlying demand in the house during the shorter hours of daylight. Come May the system will have been installed 12 months and the graphs I will be posting as part of an update confirm we have used on average 25-30% less power from the grid each month compared to the previous year.

Edited dwilliams (March 31, 2017 18:30:45)

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#7 April 1, 2017 16:10:15

TerFar
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Battery storage first impressions

dwilliams

Those are very interesting and encouraging results. With battery banks now becoming must more affordable and warranties for up to 10 years, it looks like it has finally become a sensible extension for those people with solar PV.

For your installation, an extra battery bank would be good, as the the key to extending the life of Li-ion is a slow charge rate, so more batteries would help.

I predicted that my 4 kW PV installation should be paid up before the end of year 6. I'm now into year 4 and current figure show that is well on target.

I now need to work out how much I could potentially save with 7.5 kWh wall bank. I'd probably replace my gas guzzling gas fire in the lounge with an electric fire to maximise use of the batteries.

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#8 April 19, 2017 19:05:07

WendyNorthrop
Registered: 2012-04-23
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Battery storage first impressions

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

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#9 April 20, 2017 07:59:14

WendyNorthrop
Registered: 2012-04-23
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Battery storage first impressions

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?

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#10 April 20, 2017 08:35:46

dwilliams
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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

Hi, I just wanted to acknowledge your posts but I do not have the costs to hand right now. I will look them up soon when back at home. Regarding your next post about off-peak charging and the comparison with the hydro system in Wales, there is a significant difference. As you say, they sell their “generated” power back to the grid. With the SolaX system as it works today, we would be selling back “imported” power. The SolaX system doesn't differentiate between generated and imported so it would all attract the FIT rate as the battery discharges (49p in my case) even though a proportion was purchased at about 7p. Your FIT Licensee would soon get suspicious if your generation meter readings in the winter were similar to the summer.

If I were considering purchasing a new totally new SolaX installation today I would not register it for the FIT because the return is so low; that is what I have recommended to a neighbour. However, my experience over the first year is that the reduction in the amount of imported power is considerable especially in the spring, summer & autumn months. Without a FIT being involved, charging from the grid at off-peak to use during peak periods is fine. This is especially so in the winter when PV generation can be next to nothing for days on end. I think this is where systems like SolaX can help spread out the load on the grid as well as benefitting the consumer.

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