New to solar panels, should I charge the battery to reduce bill?

maarten

Hi, I am relatively new to having solar panels and a battery and so far think they’re good.  Now that the sun has started to show and I’m seeing some real benefits I’m wondering when other people with solar and a battery charge them.  I’m on a tariff that has a cheap rate overnight which is 16.7p and my SEG tariff is 40p per kw. It seems to me that I should charge the battery every night and export everything I can at the higher rate. Is this too good to be true? This would mean me incurring a bill for overnight usage but I should make a profit of 23p per kw exported the following day which would have gone to the battery. Alternatively I can let the panels charge the battery and be bill free for the summer months. Am I missing something crucial and what do others do?

BarelySentientAI

Do you get SEG for exporting from the battery?  That's arbitrage, so I wouldn't expect so.

Or do you mean setting up the controls so daytime generation doesn't go into the battery and everything goes straight out to the grid?  And just making sure that everything you use in the day comes from the battery, with no import?

I've never seen a system set up to be able to do that.

amanda1024

I charge my battery using the cheap overnight electricity, then sell excess solar back to the grid during the day - so yes, it’s doable. Also means when there’s no sun I’m still only using the cheap electricity (by discharging the battery) most of the day. And on the occasion when there’s an incentive to use less electricity for an hour, I can set the battery to discharge into the grid. My electricity supplier doesn’t seem to mind whether the electricity is coming from the battery or the panels - surely the idea is that they’re encouraging people to get batteries (by offering a better tariff) because they want to use the demand side flexibility that offers?

Reed_Richards

How on earth did you get a SEG of 40p per kWh?  

Netexporter

I think Flux export is about 40p during the evening peak.

debitcardmayhem

Netexporter said:

I think Flux export is about 40p during the evening peak.

flux export is 25.85 peak eastern

Netexporter

debitcardmayhem said:

Netexporter said:

I think Flux export is about 40p during the evening peak.

flux export is 25.85 peak eastern

Perhaps it was Agile export that was being talked about. I'll have to watch the video again. Obviously that rate would vary, so perhaps they were talking about an historic average?

amanda1024

Reed_Richards said:

How on earth did you get a SEG of 40p per kWh?  

I was assuming it was E.On’s special rate if you buy solar and a battery off them and they supply your electricity 

maarten

I do have EON’s special rate so want to make the most of it. I think I will start to charge the battery overnight and see how I get on. I think they said that the SEG payments are made once per year so the downside is I will have a small monthly bill but overall I will export more so gain more in the long run. All I have to do now is work out how to do it.😂

mmmmikey

Hi - yes, in those circumstances I would certainly fully charge the battery overnight to make sure as much as your solar generation as possible gets exported. 

Not quite the same situation, but I'm on Octopus Flux which means I pay about the same for importing electricity overnight than I get for exporting during the day, so I might as well fully charge the battery every night to make sure that even on days with little sunshine I can always use either cheap night rate or solar energy and never need to buy full price electricity. With Flux, there is the added benefit that I can force the battery to export energy to the grid during the peak period and get even more for it.

As you've worked out, for every 1kWh of solar energy you use rather than export, you're losing 40p of SEG import so that 1kWh of solar energy is costing you 40p. On the other hand, if you fill the battery overnight with electricity that costs 16p/kWh each kWh you use costs 16p which is clearly better. There are efficiency losses to take into account, but not enough to be significant in your circumstances.

Reed_Richards

I don't get any money for export, or rather the money I do get is irrespective of how much I export.  So I have programmed my inverter to charge my battery overnight when I get a cheap rate and if the sun shines the battery will see me though the entire day rate period so virtually all my electricity usage is at the cheap rate.

In the OP's case they need to set the inverter to only charge the battery at night then maintain its minimum charge during the day so export is maximised.  They might even be able to prioritise export over domestic use.  And there might be time to charge and discharge the battery more than once overnight.  Make the most of this before Eon wakes up to the fact that their "special rate" is crazily generous.