solar novice any advice welcome

A question about : solar novice any advice welcome

Hi I am having solar panels fitted next week. I know little about this and despite reading up for hours am a bit out of my depth with all the figures. I am having 16 panels, told this is the max you can have, and my roof is 5 degrees off south.

I currently have full gas central heating/water, gas hob, electric oven. I have been advised to have large appliances staggered throughout the day with timers, not have both ovens on at the same time, and replace bulbs with leds, (something we have already been doing).

I am going to replace my towel rads with plug in electric ones, and wondered if there is any way to utilise the free daytime electric for night time heating, similar to the old night storage heaters?

Also what are the best electric heaters to use during the daytime? I have to heat the living room and kitchen during the day as I work from home.

Any other tips would be very welcome. Thank you.

Best answers:

• It's worth bearing in mind that the output of the solar panels depends a lot on what the weather's doing.
  My rough rule-of-thumb is:
• If it's sunny, and the sun is shining on the panels, then you'll be generating close to the maximum.
• If it's a bit cloudy, it will be nearer 10% of the maximum.
• If it's heavy cloud, it will be nearer 1% of the maximum.
• If it's really dense cloud or fog, assume no generation at all.

Notice the huge drop-off in generation a bit of cloud can do.
The best thing is to save up all the power-hungry things for sunny days. That's things like laundry or big baking sessions. If you're at home, then it's hardly worth bothering with timers, just don't turn on everything at once.
You can run electric heaters off solar, but unless it's actually sunny, they will most likely be using more electricity than you're generating. If that's the case, then the gas central heating is likely to be cheaper. So it's only useful when it's cold and sunny (like this morning), but not in the summer when you don't need heating, nor on grey, miserable days in the winter.
If you have a hot water tank, consider whether it's worthwhile to get one of the solar diverters that runs the immersion heater when you have excess electricity. But do the sums - in my case, I decided that the return on investment wasn't really worth it.

• I'm a little confused now!!! The salesman told me that we had the maximum panels for the government pay back scheme. He also told us that the electricity we use would be free from dawn until dusk. He described the methods he uses at home, ie: timers on major appliances, slow cooker, immersion heater etc. So has he given me incorrect information? I know he probably wanted the sale but maybe I misunderstood what he was saying.
• You may have the more modern and efficient panels. I have 18 panels, and am slightly under the maximum at 3.4kW. With the newer (and more expensive) panels, you can get more power out of each panel, and 16 could be close to 4kW.
  The newer panels may also cope better with poor light. But even so, on a cloudy day, you will probably only generate enough for the "base load" - fridges/freezers, things on standby, a few lights, etc. Power-hungry appliances, such as cookers and tumble driers can take 2-3kW each, and so will use far more than you generate on a cloudy day.
• Hmmmm.... are you paying for the panels, or is it a rent-a-roof company, where they pay for the install and you get the free electricity they generate?*
  If you're paying, then they should have given a quote for the total price, with the make/model of panels and inverter, included dc and ac switches, cable, roof mounting system, guarantee details (whether insurance backed or the"company" guarantee them), a forecast figure of what the install should generate per annum (which should be somewhere in a range of 3500kWh to 3900kWh, give or take 2-300kWh) and obviously they have a company name and did they take a deposit?
  If you could provide some of the info above, then there are plenty on here who can give some honest practical advice on whether you've got a great deal, or maybe you've been oversold?
  Unfortunately, like double glazing and financial services, there are a lot off people who promise far more than they are delivering, better to get a sanity check before you commit cold hard cash!
  I don't particularly like the comment about free electric from dawn to dusk.
  Hugely open to misinterpretation?
• He may have (over)simplified things, maybe he wasn't well informed himself or maybe was intentionally misleading you.
  People often oversimplify things by talking of solar PV in terms of number of panels. This can be quite misleading as not all panels are the same wattage or physical size. It's a bit like talking of buying milk in terms of bottles, without realising that milk comes in very different bottle sizes.
  If you're thinking of trying to replace gas heating with electricity be very careful (I'd almost just say don't) as electricity is much more expensive than gas, and a lot more harmful to the environment when imported from the grid. For example we pay 3.76p/kWh for gas and 12.72p/kWh for electricity. Your main demand for heating will be in the winter when the solar PV is producing little and will only be able to meet a small fraction of your heating needs. What you are likely to end up doing is thinking "great I've got this free electricity during the day, I'll use it with a night storage heater". Then you find that the solar electricity only meets say 10% of the heater's needs and you're having to import the other 90%, working out more expensive then just using the gas central heating...
  Ed
• Thanks for all the info, it's getting a bit clearer now. I will check what system we have been quoted for when I get home and post more details.
• I tend to look at my electricty meter at certain times when the PV output is stable - say 500w, 1KW etc and when the red light stops flashing you know that is your daytime base. I then do the same later, say 2kw but with the washing machine on and see if I am exporting still or importing. I love the iBoost as I know this maximises useage. Don't get too hung up over it or it'll ruin any enjoyment - just be a bit smarter i.e. if you can wait to do the washing when it's sunny then do it, but if not you can't help it and will be saving a bit anyway on the small amount you are producing.
• Here are the details I have of the system to be installed this week. Hope its the correct information. Thanks.
  https://i1157.photobucket.com/albums/...0/IMG_2315.jpg
  https://s1157.photobucket.com/user/vi..._2316.jpg.html
• Sorry about that, I'll try again
• Hiya vix.
  A few points.
  I totally agree with Eric that Ј349 leccy savings is OTT. Working from home you may save Ј200, but again, as Eric said you'd be lucky to manage that.
  That generation figure of 2,908kWh doesn't sound right for a south facing roof. That's only 727kWh/kWp. To put it into context, for me in Cardiff, my ESE roof has a target of 808kWh/kWp and my WNW is 679. Do you have shading problems, or do you live very (very) north? Have you tried the generation estimator PVGIS mentioned in the FAQ's section 5?
  [Edit - I notice that the quote says that orientation is 85, but I don't know what that means. Is it from North, so it's 5d above East. Or is it an azimuth from the sun (south) so 5d below West. Or perhaps, in an attempt to match your statement of 5d off south, do they use a scale where South is 90 and East/West is zero? M.]
  You don't mention the price. Are you happy with it? Is it in the Ј6k region, if you don't mind me asking?
  Mart.
• Hi Thanks for the replies, the guy said we are 5 degrees off south facing (I thought it was SE) and we are in Sheffield, so northish. and there is no shade on the roof the panels will be on.
  The cost is Ј8500 which I thought wasn't too bad as the panels are Sharp panels and the reviews appear to be good, but really had no idea of the current cost as its a couple of years since I looked into it. At that time a friend had paid over 4000 for 4 panels.
  I am anticipating using the pay back payment towards the repayments but made sure the whole repayment is comfortably affordable.
  I had originally thought it would be more than that for 16 panels. Also we were made aware of the changes due in January to reduce the payback tariff.