Charging Battery at night rate

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

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.

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 😁

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

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

Changed a little.

It is actually 47.77 after VAT :-)

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.

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 😁