Charging Battery at night rate

alan kelly

Hey folks,

I have a 5kw Pure Drive battery attached to my solar kit. Wondering if anyone out there is charging the battery off the mains at the night rate. 5kw at night rate is almost a quarter the price than day rate. Is this possible and then to time when you want it to use the power ie after 8am ?

unkel

Yes we all do. Night rate for me is 7.9c / kWh and day rate is 28c / kWh, so I load up my 30kWh battery fully at night. I use virtually no peak rate electricity during any time of the year. I use the battery also to partially heat my house with electricity during the day because it is cheaper and cleaner than using gas

The night rate hours are 11PM to 8AM in winter and 12PM to 9AM in summer

alan kelly

https://www.boards.ie/discussion/comment/120139148#Comment_120139148

Cheers, I need to set this up. 30kw Battery is a big boy. What type is it ?

I have a Pure Drive and need to figure out the steps. Im sure Google is your friend 😉

unkel

30kWh 😉

Will be 45kWh before the end of next month

@alan kelly - "I have a Pure Drive and need to figure out the steps"

You set it in your inverter typically. What hybrid inverter do you have? If it's a Solis or a Sofar ME3000SP, they have their own dedicated threads in this forum. Have a look there first.

alan kelly

https://www.boards.ie/discussion/comment/120139233#Comment_120139233

Thanks , Its a Solis. Ill look through the thread... Jesus 45kwh , Are you purchasing and installing yourself ?

unkel

https://www.boards.ie/discussion/comment/120139254#Comment_120139254

Yes, 40kWh in CALB 200Ah cells is a bit over €5k. Not an awful lot more than some people pay for fancy looking pre-made 5kWh batteries 😁

alan kelly

Cool. Sounds too good to be true😉 but I’ll check it out 👌

Jonathan

https://www.boards.ie/discussion/2058280603/charging-battery-at-night-rate

This video will guide you through the steps on a Solis inverter to charge your battery from grid.

unkel

https://www.boards.ie/discussion/comment/120139590#Comment_120139590

LOL, why do you think it sounds too good to be true? It's very simple really. You charge up with super cheap night rate (which is also mostly from zero emissions, renewable wind energy) and you use it when electricity is very expensive

Most people with a battery also have solar PV, so you load up your battery when the sun shines during the day and you can't use all that free electricity, and then your battery powers your home at night.

alan kelly

I’ll prob ping you with a few questions once I’ve done a bit of digging 😀

Ginger83

https://www.boards.ie/discussion/comment/120139233#Comment_120139233

Would you have a need for 45kWh? Seems like quite a lot

unkel

https://www.boards.ie/discussion/comment/120139874#Comment_120139874

The 5kWh on top is a little bonus / backup. Don't need it. And as for the "do I really need 40kWh?"

Well no, not strictly. But we are getting these batteries free of VAT at a good price, so they will keep their value very well. So basically even if you use them for a year or two, there will be no depreciation, so no costs really. And the batteries will start earning their keep immediately. I try and heat as much of my home with electricity in winter. From night rate directly and from battery later in the day. And I have a very large solar PV setup, so in summer the buffer of 40kWh will keep my going without buying any electricity from the grid, even if we have a couple of rainy days in a row

And as an example, if I fully load 40kWh into the battery in winter, I save 40 * (day rate minus night rate) = 40 * (0.28 - 0.08) = €8. Now there are losses going in and out and some of it I use for heating, which I could have done with gas costing €0.15 per kWh. And if I go over a 2000 unit threshold, I pay more for my night rate. But a saving of €3 at least per day, which is €180 for each billing period. Let's say €1000 per year, meaning after 5 years the batteries, still worth at least half of what I paid for them by then, will have fully paid for themselves

So you see the question is not really do I need it, but how much money are they returning for me

Ginger83

https://www.boards.ie/discussion/comment/120139897#Comment_120139897

Excellent explanation thanks. I have a system ordered and awaiting installation but have yet to decide on batteries.

horse7

https://www.boards.ie/discussion/comment/120139148#Comment_120139148

I,d. Love to know what energy supplier is giving you those rates?

graememk

https://www.boards.ie/discussion/comment/120145005#Comment_120145005

Energia.

That plan is now 45ish /13.5 unfortunately

ELM327

Still the best deal out there though

yankinlk

--- meant ot post this in FIT --- argh

horse7

Changed a little.

slave1

https://www.boards.ie/discussion/comment/120145036#Comment_120145036

Jeez, 45c day rate! Haven't looked in ages, thankfully running around 1kWh a day on day rate on average

Galego

https://www.boards.ie/discussion/comment/120145784#Comment_120145784

It is actually 47.77 after VAT :-)

ELM327

Still the best deal out there, especially in PV forum as most posters should have a battery/ies to minimse or eliminate day usage. It's the night rate that matters. On my last 2 month bill i had about 40kWh of day units and just under 1800 night units (at 7c !)

unkel

https://www.boards.ie/discussion/comment/120145928#Comment_120145928

Aye, but there is a penalty to be paid if you go over 2000 night rate units per billing period. You seem to have avoided that, which quite surprises me with a big house, two EVs and loading up a 20kWh battery every night.

DC999

https://www.boards.ie/discussion/comment/120145928#Comment_120145928

Wowwww, that is an amazing ratio of 1800 night to 40 day.

ELM327

https://www.boards.ie/discussion/comment/120146068#Comment_120146068

Yes but even the penalty rate isnt so bad, 15c or so. I'm not actively trying to avoid it anyway, especially since you only pay it on the units from 2,001 onwards and the first 2000 kWh remains at the 7c rate.

unkel

Indeed. But for me it's an important difference as with the losses of night rate going into the battery and then out again, the excess units are significantly more expensive than using gas. And I can entirely avoid them if I didn't heat my house partially with electricity.

Waiting 3 months on my Energia bill now, which doesn't help. I know I can take meter readings myself. But still...

unkel

https://www.boards.ie/discussion/comment/120146590#Comment_120146590

98%

Most of us with a 20kWh or bigger battery can do that or thereabouts, almost without doing any micromanagement. Particularly if we have an inverter that can charge / discharge at at least 5kW

Unless we make a few mistakes like plugging in the car during the day, or we have battery outages because of maintenance, and stuff like that 😁

ELM327

https://www.boards.ie/discussion/comment/120146623#Comment_120146623

Yes I send in a meter reading on the first of every month. This is to avoid estimated bills.

graememk

https://www.boards.ie/discussion/comment/120146660#Comment_120146660

just got the email for the meter read, 76 day, 2886 night. No gas or oil used. Night rate averages out to 9.97

I had a couple of automation failures (need to look into that) and a day or 2 where I had to charge the car during the day.

Sometimes the inverter doesnt like the crusher starting, so it slowly ramps of after an incident like that too.

smax71

https://www.boards.ie/discussion/comment/120139770#Comment_120139770

I had been thinking that a 10kwh battery would be good going! I'm looking to install a 5kwh dryness with a 6kw inverter with a view to installing a further 5kwh dryness in the near future, each costing in excess of €2.5k, so €5k for 10kwh ..big difference! I'm assuming that you need a decent bit of knowledge to install those CALB batteries DIY? I'm hopeless with electricity so would be reluctant to go down that route for a while. However wondering if possible to link those DIY batteries to a dryness in the future instead of adding another dryness or would you need a completely independent circuit (does that even make sense) for the DIY batteries?

The other issue I would have is space as I'm thinking of locating the inverter and dryness battery in the house to avoid having to cut drive and footpaths to route a cable into consumer board from a garage. However I'm assuming 30+ kWh of those CALB batteries would require a fair bit of space. Would it be possible to locate additional batteries in the garage and link to inverter with approx 12m of cable or should all batteries be adjacent to inverter? As you can gather a complete noob about all this stuff!

alan kelly

Have you guys got Solar also ?

I’d love to see a basic line diagram of how you have the additional batteries set up ?

ELM327

https://www.boards.ie/discussion/comment/120152246#Comment_120152246

Yes, I have 8kWp of solar PV, a 6kW inverter and 20kWh of battery storage. 4*5kWh dyness batteries (for now, I'll be hopefully changing this later this year for more calb cell based storage).

It goes PV panels on the roof into the inverter, batteries connected to the inverter, then the inverter via the CT clamp uses the solar incoming (if any) to power the house. Else it pulls from the batteries. I charge the batteries overnight too, these days, but in the summer it's 100% off grid.