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Making the best of a bad solar PV installation

Postby ticktockhouse » Tue Jul 14, 2020 1:09 pm

I'm after some practical, expert advice on changing a solar PV system.

I've got a 4 kW system which I probably paid too much for in 2016-ish when FiTs were still a thing and which is annoyingly inefficient, mainly due to the Growatt SP2000 battery which only kicks in after dark, when the panels are no longer producing.

Our usage pattern tends to be 3-4 kWh in the evening. In the summer, the battery, which has grabbed the power during the day, holds onto it through that usage peak in the evening and only starts discharging about 9pm, when the house is only drawing around 300-500 W. We've also got Economy 7, so it's doubly useless at that time.

I haven't had much luck getting in touch with Growatt, so I would like to try and sell this to someone who might get a bit more use out of it, and try and knock the price off a new, more useful one. Something with a bigger capacity and that could be used to "top-up" the solar when needed during the day or be used at night etc. Basically, it should knock a bigger chunk of our electricity bill. Any advice on ebaying, etc.? I don't think I'd miss it much if I got rid of it before this winter - it doesn't help much then...

We're also looking at a Sunamp heat battery to replace our gas boiler and I'm planning to try and use Octopus Agile to charge that when the electricity price goes negative (as well as obviously off the panels and/or Economy 7). This should be happening a bit sooner, with any luck..
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Simply Build It

Postby matt_br » Thu Jul 06, 2023 10:30 am

Hi, not sure the battery would be the problem, more the way it is managed and what SEG you are on.

The Agile tariff is by far the bast – with people charging their batteries over night at the cheap rate and selling back to the grid during peak times.

You’d need to cancel the FIT and start an SEG though – which you’d have to do if you change your equipment anyway.
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Postby ericmark » Thu Sep 28, 2023 8:47 pm

Interesting what you say, I am new to solar power, but as an electrician I can see the problems. With me without E7 a little easier to work out, but it is when and how solar is used.

It seems we have thresh hold limits, the point when we start charging a battery or heating our DHW, and it seems these need fine tuning.

However the question is when is it worth changing what we have? Our battery will not see us through the night, and in the day when we have a good day we are exporting,

The maths is not easy, we looked at a second battery, but decided it would not pay fo its self.
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