This is going to be our first winter with solar and battery. I’ve noticed that the battery will not reach full charge during cloudy days. I was wondering what others do as the days get shorter and potentially cloudier?
I setup (using WonderWatt) a nightime schedule that charges the battery from 11:30pm to 6:30am to a maximum of 50%. Using cheaper overnight electricity for the following day (I work at home) and the solar then tops up given the cloudy conditions.
Anyone have any other ideas?
Also has anyone investigated a blanket for their battery for over winter to keep it’s temperature up?
I don’t think a blanket is really needed - my car is kept outside 24/7 and has been for 8 years, with no negative impacts on the battery. That gets VERY cold sometimes and though the power limit is reduced, your home battery isn’t anywhere near as intensively used as an EV battery is.
So - I wouldn’t worry.
On your other query, I’d just monitor the weather and see how you go. Even if you get no solar, you’d still be charging it at cheap rate.
It all depends on your relative cost for night/cheap import against your export tariff.
If the night tariff is cheaper than the export it can be more cost effective to charge to 100% at night, then any spare solar gen later that day that is over your consumption/battery charge will pay back more in export.
I have an EV also, but I’m wondering if the GivEnergy battery will charge at a slower rate when cold. If so then it would limit the ammount you could charge from Solar (sunny winter day) or from the grid. Slower chage rate means you won’t get your desired SoC for the night/next day.
Aparently Tesla Powerwalls have a built in heater to avoid this issue.
There is a distinct lack of cover suppliers for solar batteries, either it really is not an issue or I’m the first one to think about it??
Yep, my overnight tariff is £0.07p/kWh, definately cheaper than day rates, charging the battery to a level that will suffice for the day is where I’m at. Started with limiting it to 50% SoC from 11:30pm to 6:30am. It was done well before 6:30am.
However, what I’m wondering is with a colder battery, likely to see slower charge rates, which will extend the time required to meet the required SoC.
Keeping the battery a bit warmer may help .
So, how long does it take to charge your battery to 60% now? You have a 7 hour window to reach 60% SoC, that’s plenty of time even if there is a reduction due to really cold weather. Even 100% should be easy to reach.
But 60% is not getting the best out of your system for the winter months. As Simon_C says, you should be aiming to charge to 100% at 0.07p/kWh and holding the charge to 6.30am. If you then don’t use all of it during the day, then there’s less to charge in the evening - it doesn’t go wasted. Your solar will be topping it up where it can during the day, with any excess being exported to the grid at a higher export rate.
You are lucky that your battery will last the whole day!
Some people will also discharge the battery towards the end of the peak period to get the export gains there too.
Hi Simon, i am with your comments, but don’t see this discussed often. When overnight tariff is less than half the export tariff then you only want solar to charge any batteries “if needed and as decided by you”, but my Apps default to the reverse and i find it very hard to stop this wasted opportunity.
For example, My EV charges fine overnight and i never need to waste valuable solar in my car, by my EV charger will do this automatically in summer before i wake up and then stop in manually.
The GivEnergy system likewise. We must all need Eco mode in the daytime so to use the battery to minimise or prevent daytime import. But then by default, until i wake up and fix it, the solar will top up the battery to 100%, replacing house consumption between 0530 and sun-up. I do this by adjusting the charge rate to zero every morning, and back to 1.5kW every evening after sunset (using the Mobile App). My 9.5kWh battery is enough for the while house demand most days, and certainly too much if fully charged at sunset each day.
What a pain - I think I need Home Assistant and a Raspberry pi to fix this. Any easier solutions?
I charge on cheap rate overnight when the weather is going to be bad. I ended up insulating my AIO last year when we had a long cold spell, it does make a difference.
On days that I charge my EV, I set a ‘Timed charge’ on the battery between 23:30 and 5:30 to maintain at 80%. This keeps most of the solar stored energy to be used the following day whilst the house and EV run on the grid for that one night. I do this via the Giv-Energy App, just turn on the timed charge.
For days where the battery has not been charged enough, i.e. not much sun, I use the WonderWatt site to charge the battery from the grid overnight. Then use the battery during the day if the weather is still gloomy. At least is then a third of the price of usage during the day. I work from home so this helps cover the 200-300 watts being consumed daily.
Using this strategy, I only have to change things when I charge my EV or when the weather is gloomy. It’s still a pain, but I’m waiting for WonderWatt to get weather data into battery charge scheduling, then this would make it even easier.
HTH.
GivEnergy Alexa Skills are basic - this would be good to have skills like…
“…ask GivEnergy to turn on/off timed charge”
Hi, i am assuming your solar is around 4kw, even on a dull day you should be able to surfice your daily usage, when things like kettles and other high drain items are used the battery power should take up the excess requirment. If your on Octopus Intellegent Go, try charging to maybe 75%, i think its just a game of trial and error depending on the system you have.
I have 2 x 9.5Kw batterys through an AC Coupled inverter, and approx 7.5Kw of solar. My daily usage is around 15-18Kw of power so my normal set out for winter is charge to 75- 80% from 11:30 till 05:30, the solar does the top up and i seem to see the house running on the solar most days, and only the high drain items pulling off the battery.
Good luck getting the right balance, but im confident that once you have a system to work too, the benefits are certainly worth the loutlay.
Pretty much spot on, 3.4kWh from Solar. I have a 9kWh battery. First stab at the charge needed was 80%. As you say it’s a little bit trial and error to balance it out, but is seems to be about right so far.
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