Share your experience of night time battery charging

Hey ​@madgolfermk80 

Welcome to the community, I’ve added a badge for your battery.

I wonder if some of our users might have some advice they can share on this, who they’re with and if they do this. ​@juliamc ​@BPLightlog ​@waltyboy ​@EverythingNeedsAUserName 

Yes - but it needs to be controlled.

Any I do is at an off peak rate and the battery condition (no. of cycles; charge/discharge levels) need to be understood.

What are you looking to achieve?

I do, I’m on Octopus Intelligent Go as we have an EV so get a cheap rate period overnight. It also charges on excess solar (that’s very much a summertime thing as there’s rarely excess solar the rest of the year). Unlike BP I haven’t taken battery condition into account ! Oops ! 😳

Thanks ​@Peter E I will !!

It’s a GivEnergy and as I haven’t paid for the monthly subscription I can’t now see exactly what’s going on with it now anyway.

Yes, in winter, on an economy 7 tariff. Night is about a third the cost of daytime. 

Summer, the battery is left to its own devices. Mostly it doesn't need anything other than solar.

Spring and autumn. I tried charging to a lower % but it broke the on board system controllers. I got free replacement batteries and a warning to always recharge to 100%.So far in September we had one really grimy day with cloud and drizzle, on which we imported 7kWh. My batteries won't allow the charge to drop below 10%.

Once the sun's power has gone we change to overnight charging. Typically mid October to 1 March. 

I'd love the ability to do what ​@BPLightlog suggests. My phone and tablet batteries have lasted far longer than expected by setting a max 80%. Note you'll use slightly more kWh due to inefficiencies in charging. Your battery capacity also has to allow for any system minimum and any battery conditioning upper limit your system allows.

Just had Solar panels and 16 kWh  battery installed 

OVO don’t do a tariff for overnight charging 

did think about economy 7 or going to octopus or standard rate 

any help would be appreciated 

Hi ​@madgolfermk80, apologies for coming late to your post!  
 

As others have said, for those on time of use tariff it makes sense to charge the battery during the cheaper period.  I have largely the same routine as ​@EverythingNeedsAUserName, in the six summer months my solar panels handle everything, but from October to March I charge between 12 midnight and 6 AM (EonNext EV tariff cheap rate) and I top up again in the day from 10 AM to 2 PM, when hopefully even in winter the solar panels contribute something.

The one key difference in my own setup is that the solar panels and the grid tie inverter have no direct relationship with my relatively small battery and it’s associated relatively small grid tied zero export inverter.  I had worried initially a few years ago when I first got the small inverter and battery that it would somehow “upset” my rather elderly but super reliable Fronius inverter, but not a bit of it.  To the naked eye they just get on with things and ignore each other.

Although my battery is a mere 2.4kWh, our house “stealth” stuff totals an average of only 80Wh when we’re asleep and around 120Wh when we’re up and about working the lights, ‘fridge doors, TV etc.  A small house with two retired folk is easy to manage, but even so we have a family fridge/freezer, a small chest freezer, router, video doorbell, two phone/tablet chargers always on, a variety of smart plugs, Echo dot, smart room stat, plenty of lighting, garage roller door sensor and all the other modern trappings that folk accumulate, such as electric toothbrush always charging, cooker and microwave clocks and a myriad of neon and LED indicators in switches etc.  I used to go around switching off the smaller stuff but I found it didn’t really impact on our usage, and indeed the zero export inverter seems to lose a bit of its smarts if total house demand drops below around 30 watts.  A Watts range of 50-ish to occasionally 500-ish (if the fridge and freezers all kick in simultaneously) seems to suit it fine.  Bear in mind that I’m talking only of the “always on” or more accurately “always on standby” stuff together with lightweight stuff such as LED lighting and our small TV.  The bigger stuff like washing machine and dishwasher and occasionally the electric oven  we run at night in winter or during a sunny day in summer. The cost of other big stuff like the hoover, microwave etc we just take on the chin occasionally.  So, to summarise, from April to September the house electricity costs 20p or so three or four times a week to run big stuff, (plus around £18 monthly to charge the EV overnight) with battery charging free during the day, and during the  winter the battery re charging costs around 2 kWh overnight at 9p per kWh plus a further 0.5 kWh during the top-up session around midday.  Those winter overnight battery costs and the short daily top-up costs also include the modest house “always on” costs. 

I

It’s to avail ourselves of the cheap overnight tariff following getting our EV last May that led to us very regretfully leaving OVO in May and joining EonNext…EDF actually offer 7 hours of even cheaper overnight electricity rather than Eon’s 6 hours at 9p, but we chose Eon because at that time there was vague talk of OVO and Eon eventually combining, though I haven’t heard anything recently.  So maybe at the end of this fixed tariff next May it might be worth my looking at EDF again.  
 

Actually, one wouldn’t even need PV panels to shift usage and save money in this way, for a small house anyway; even with inevitable charging losses, it makes sense to utilise cheap overnight rates in order to cut back on expensive daytime or even more costly peak daytime rates.  But of course PV panels vastly reduce costs further: even today on a cloudy day in Sunderland (NE England) the panels are responsible for the main Fronius inverter exporting 236 Watts as we speak, the surplus over and above what the house is currently consuming. 
 

Apologies if this has been rather long-winded!  Do let us know how you proceed, always of prime interest to see the diverse ways folk set about reducing energy demands…all the best, Walt

Thank you so much for your kindness as ever, Ben, so much warmth always from this wonderful forum and its knowledgeable and kind folk.  Cheers….Walt