Squeezing the most from Solar Panels

If you have Solar Panels where a FIT payment is based on what you produce, rather than what you give back to the grid, then you will probably already be trying to use as much of your generated energy as you can. Typically the main areas might be trying to run things when the sun shines, such as:

  • Washing machines
  • Dishwashers
  • Dryer
  • Cake Baking
  • Charge up phones and other chargeable battery devices
  • Mow lawn

which you could do via the timer if out all day.
However I though I’d start this thread to describe the things I am doing outside the usual, and hoping that others will respond with ideas.

  1. Oven pre-heating: When you are not generating enough to turn on the oven on full heat (~2.4kW), then partially heat up the oven by turning on the half grill option for 5 mins.
  2. Free Hot Water via an Immersion diverter. These are add on devices that are fitted between your immersion and your consumer unit, and divert any surplus (even down to 50Watts) to your immersion. This allows you to squeeze every last drop, particularly over winter and intermittent cloudy days. In my case the result is free hot water all summer, and most of winter. This has equated to 1400kWh in a year, and will get my money back from the cost of the device in less than 3 years.
  3. Free Heat: The immersion diverters can also be used to power simple (i.e. no electronics) electric heaters. So when the water is adequately hot, I disconnect the immersion, and plug in an electric storage heater to the same circuit. This has meant many winter days where I don’t need any gas heating, or just a top up. TIP: You can get simple LCD thermometers from Amazon for about £2 which you can place on the metal part of the copper cylinder to see what temperature the water is at.
  4. Lower cost washing machine usage. There are times when I am not generating enough energy to run the 2.4kW washing machine. So given I have effectively free hot water, once the clothes are in, I then pour in several pints of hot water from the tap, which means that the washing machine doesn’t need to be on 2.4kW for very long.

Yes I know I could get a battery storage system, but they are still quite expensive, so what do you do to get more from your generated power


Current thinking is buy an electric car charge that and use it as an energy store and I suppose you could use it as transport.

certainly my longer term aim, but my Ford still has a few more years on it yet. Is it just Nissan that do that at the moment? I believe there are energy companies (e.g. Agile Octopus electricity tariff) that offer variable rates that change hourly that can be very low at night, and sometimes they even pay you to have electricity

I don’t have personal experience of the arrangement, but I do know that our utilities department are advising companies and government of future energy strategies and they seem very keen on cars as ‘mobile storage units.’

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Storing electricity has always been a bit of a challenge, that is why the first choice is to export on to the network. I understand that there are parts of the country where they cannot accept any more power from renewables such as PVs because they can’t find a use for it and it just pushes the voltage up locally.

All a bit tragic really

Any ideas on cleaning solar panels - should they be left alone? Or cleaned regularly - DIY or professional?

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My understanding is that they are self cleaning these days, and in actual fact mine have stayed clean over the last 2+ years. I recall seeing a YouTube video of an American oldish man standing on his roof in the winter knocking the snow off, however when you consider that you may only make a £2-£5 a day in electricity in the winter, was it really worth the risk?

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I use a Marlec iBoost to divert otherwise-exported power to the HW tank; this comes after the Tesla Powerwall is topped up. In 7 years I have diverted >7,000kWh in to the HW tank; that equates to about £1,000 of free power, for the cost of the widget @ <£200.

I had hoped that I would only use (cheap) night rate electricity for 8 months of the year, and be “off grid” for the remaining four, but it hasn’t quite turned out that way. Still, over the year >90% of our imported power is at the night rate (GBP0.05/kW). The payback period for the Powerwall is much longer than the solar panels (with FIT), but I’m still glad that I bought one.

One problem with feeding otherwise-exported power to an EV is that there is a minimum charge rate of (IIRC) 1.4kW - something that was set in a “standard”. The times that I export anything like >1.4kW are vanishingly rare. (4kW PV, West Sussex). As I result, I don’t even try to charge my Model3 with my panels.


These diverters are such a brilliant thing, and I can’t understand why they are not publicised more, as they really are a no-brainer. I have an Apollo, which has an advantage of two outputs and the second can be used to take over when the first one is off.

A Powerall would be the Naim equivalent, but I can’t see myself getting the money back (plus SWMBO wouldn’t go for it). The heating of hot water is effectively a poor mans energy storage system albeit not to Powerwall levels. I will go EV someday, but fully see that the Solar energy alone would not be enough to keep the car charged on many days given standard milage use. Having retired, my milage is dropping so will see.

Is there anything extra you do with your generated electricity beyond the usual?

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