Soldato
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Solar panels and battery - any real world reccomendations?
- Thread starter GinG
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Hi all,
Maybe not the right thread but seems to be a wealth of information here. I'm looking at Rodders' power, and it says Generation and Efficiency - what exactly does that mean? Say the generation is 15 and the efficiency is 3kwh. Does that mean they could only use 3kwh out of what they generated?
We got a quote from Project Solar for 10xEvolution Titan 455w and a 8KW batter for around £16k~ which seems steep, is it? I've also heard massive mixed reviews about them, has anyone used them?
One final question too - we use around 3,600kwh a year and their projections are we should generate 3,900 a year, obviously winter months will be lower but would this basically mean that during the summer we should be neutral but in the winter have to pay a bit for energy from the energy provider?
Thanks
Maybe not the right thread but seems to be a wealth of information here. I'm looking at Rodders' power, and it says Generation and Efficiency - what exactly does that mean? Say the generation is 15 and the efficiency is 3kwh. Does that mean they could only use 3kwh out of what they generated?
We got a quote from Project Solar for 10xEvolution Titan 455w and a 8KW batter for around £16k~ which seems steep, is it? I've also heard massive mixed reviews about them, has anyone used them?
One final question too - we use around 3,600kwh a year and their projections are we should generate 3,900 a year, obviously winter months will be lower but would this basically mean that during the summer we should be neutral but in the winter have to pay a bit for energy from the energy provider?
Thanks
It’s 100% steep. Presumably that’s over 1 south(ish) roof?
In terms of generation, essentially, yes. Even with the battery you’ll be exporting in the summer and importing in the winter. There are obviously daily variations, you still get some rubbish days in summer and likewise you get some very bright and sunny ones in winter.
In terms of generation, essentially, yes. Even with the battery you’ll be exporting in the summer and importing in the winter. There are obviously daily variations, you still get some rubbish days in summer and likewise you get some very bright and sunny ones in winter.
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Soldato
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no - the efficiency is based on how much each kw of panel is producing - so if you have 10kw of panels and produced 30kwh of solar, your efficiency is 3kwh/kw of panels
It's a direct SW roof. Ok, cool, so in theory, then in the summer bills should either be next to nothing or potentially nothing, however in the winter on some days we may have to pay for some import.
Ok so the generation then it was it generated, so on the days that 15 was generated, if you used 3KWH, stored 8 in a battery then 4 would go back to the grid?
Thanks
Soldato
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Only other consideration is if you have a hot water tank you can get a diverter (probs 350-500 quid) that can send excess solar generation into your tank.
They work pretty well. Good days recently batteries for me back up to 100% early afternoon and 2-3 hours of energy going into the hot water tank.
They work pretty well. Good days recently batteries for me back up to 100% early afternoon and 2-3 hours of energy going into the hot water tank.
Soldato
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Nah its true, my panels are pure west facing but by mid morning even if its lightly cloudy I am getting 1kw quite frequently
Soldato
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Define: good amounts?
Is it winter, dark and rainy outside? if yes then solar may as well be 0.
It will generate something if it's light outside, and the brighter it is the more it will do. It's not sunny here but generation ticking along at 600-800W currently.
Panels seem to have 3 gears, nothing, doing a bit because it's light enough, or racing along because it's in direct sunlight.
P.S. your quote is definitely steep find another company! and more panels is good, even if 4kW of panels covers you pretty well now, what about when you add in heat pumps, EV etc? If you have the space, add more panels and a bigger inverter, future you will thank past you.
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Interesting, I'll be honest I'm not sure we do, we have a combi system so we don't have to heat anything, we just turn on hot water and wait 30 seconds and we have some.
That's pretty cool, is that 1kw over the whole day or do you mean you've generated 1kw by mid-morning?
Yea' I guess it's similar to asking how long the piece of string is with what was said lol.
So when you say generation ticking at 600-800w, do you mean over the day or currently that's what's being produced per hour? Sorry this solar stuff has really pickled my brain lol.
Ok, I will defo check out some other companies, it did seem a lot!
Thanks
Soldato
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Yes that would be correct....if you have grid export, other wise its just wasted
I would say in winter you’ll be paying for most of your power needs, spring and autumn can vary a lot between importing and exporting and summer you’ll cover most of your needs and what you export will probably cover the cost of what you import.
The benefit of having a battery is that you can charge it up off peak for next to nothing in the winter.
The person you have been given a quote by should be able to give you a breakdown month my month of the solar generation for your roof. This is of course ‘typical’ and the actual will vary year by year but it’s usually pretty close.
If you have an electric car look at tariffs like octopus go or if you don’t have a EV then there is octopus flux.
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Soldato
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If you have a combi then almost certainly no tank. So that option is out I am afraid.
One of the big benefits of batteries is being able to charge them off peak and use them whilst your solar isn't generating.
You haven't mentioned anything about this side, were you aware?
Edit, on the 1kw thing. No thats the energy production rate. So production/usage rate is in kW where as your overall over a time period is kWh (we tend to drop the caps here)
So eg if I generate 2Kw for 30 minutes I have a total generation of 1kWh. You pay per kWh
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Soldato
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It's good to ask questions and learn stuff for sure! don't worry!
If a kettle uses say 2kW of electric to run at a constant rate, but you had it sat there for an hour without stopping, you could say that the kettle used 2kWh of electric (2kW, for an hour).
1 kW = 1000W, so 0.8kW would be 800W in my example.
kW or W is a measure of usage at a point in time, but doesn't take duration into account.
kWh or Wh takes that point in time and adds a duration component to it. A kettle normally would use a lot of electric but would not be on for long, so it may take 2kW to power it, but it could only be on for say 2-3 minutes, therefore it would use way less than 2kWh to do it's job.
My PC uses around 100W just being sat there doing not much. in an hour it will use 0.1kW of electric. if it had it on all day then it would use 0.1 * 24 = 2.4kWh in total.
So when I refer to ticking along at 600-800W, it would be reasonable to assume in the span of an hour it would be able to generate about 0.7kWh (average in the middle figure).
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Thanks mate, that's a great ELI5It's good to ask questions and learn stuff for sure! don't worry!
If a kettle uses say 2kW of electric to run at a constant rate, but you had it sat there for an hour without stopping, you could say that the kettle used 2kWh of electric (2kW, for an hour).
1 kW = 1000W, so 0.8kW would be 800W in my example.
kW or W is a measure of usage at a point in time, but doesn't take duration into account.
kWh or Wh takes that point in time and adds a duration component to it. A kettle normally would use a lot of electric but would not be on for long, so it may take 2kW to power it, but it could only be on for say 2-3 minutes, therefore it would use way less than 2kWh to do it's job.
My PC uses around 100W just being sat there doing not much. in an hour it will use 0.1kW of electric. if it had it on all day then it would use 0.1 * 24 = 2.4kWh in total.
So when I refer to ticking along at 600-800W, it would be reasonable to assume in the span of an hour it would be able to generate about 0.7kWh (average in the middle figure).
I'll be honest, no lol. I think he did say something but I don't think I understood it. My gf literally just sent me through something about octopus energy showing that between like 2-5am you can use electricity for like 20p per kwh so that seems decent.
Thank you for the explination.
Soldato
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Thanks mate, that's a great ELI5
I'll be honest, no lol. I think he did say something but I don't think I understood it. My gf literally just sent me through something about octopus energy showing that between like 2-5am you can use electricity for like 20p per kwh so that seems decent.
Thank you for the explination.
Thats flux that is mentioned above, specifically designed tariff for solar users.
So yeah ideally worst half of the year (approx) you charge batteries over night in that window, use them during the day, and in effect switch a good chunk/all your expensive daytime units for cheaper over night ones.
Summer is probably limited benefit from charging.
Flux also has very good export rates so over generation is not so much of an issue then. Its not an issue as such, but its annoying to get getting paid 4p a unit export and the same day be paying 34p to import!
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@cHk4 if you have a large array and likely to overproduce which can happen even in the winter, consider batteries and consider how much your home typically uses on a day and add 10-20% ontop to be safe. For example my array is "modest" at 6.4kW but I am 30 mins from the south coast and have south facing roof - in the winter I have been able to fully charge my batteries and even export quite a few days. I also have a hot water diverter. So don't write off winter completely - yes you will have less good generation, BUT, you will STILL be taking a significant chunk off your monthly electricity bills.
Another thing to think about is tariffs. I don't have an eco 7 tariff - those are dual rate tariffs that have cheaper electricity in the evenings during a certain time window (it varies based on your postcode and supplier I think). If you know you're going to have a bad solar day you can force charge your batteries at night on the cheap rate which then gives you effectively that cheap rate electricity during the next day as you rely on your batteries to power your home.
More and more tariffs are popping up now that offer competitive rates for solar and battery owners.
I know nothing about this bit but there are also interesting tariffs for EV owners as well - but I'll let others explain!
I personally wouldn't focus on exporting as a priority, focus on storing as much energy as possible. It's got to the stage where I'm considering another battery as 9.5kw for the size of our home and the rate at which it charges when there's a lot of sun means I end up exporting fairly quickly even after the hot water has been heated! That said, having a good export rate does make it quite nice to have. I mean over winter I've earned over £20 if not more - I can't remember.
As you rightly said, in the summer you're likely to use all your excess energy, your batteries will be full and you will probably for at least 2-3 months if not more, be exporting a fair bit, so going on a good export will be good. You could easily save over £200 over those months through electricity savings alone, excluding anything you earn on exporting - you could possibly earn well over £20 a month.
Ultimately the reason to go for solar is to reduce your monthly bills, create a short/medium term investment for good returns in the long term, and ultimately be able to use electricity with the piece of mind that you're not contributing to carbon emissions or grid usage.
That said, 16k is very steep.
Another thing to think about is tariffs. I don't have an eco 7 tariff - those are dual rate tariffs that have cheaper electricity in the evenings during a certain time window (it varies based on your postcode and supplier I think). If you know you're going to have a bad solar day you can force charge your batteries at night on the cheap rate which then gives you effectively that cheap rate electricity during the next day as you rely on your batteries to power your home.
More and more tariffs are popping up now that offer competitive rates for solar and battery owners.
I know nothing about this bit but there are also interesting tariffs for EV owners as well - but I'll let others explain!
I personally wouldn't focus on exporting as a priority, focus on storing as much energy as possible. It's got to the stage where I'm considering another battery as 9.5kw for the size of our home and the rate at which it charges when there's a lot of sun means I end up exporting fairly quickly even after the hot water has been heated! That said, having a good export rate does make it quite nice to have. I mean over winter I've earned over £20 if not more - I can't remember.
As you rightly said, in the summer you're likely to use all your excess energy, your batteries will be full and you will probably for at least 2-3 months if not more, be exporting a fair bit, so going on a good export will be good. You could easily save over £200 over those months through electricity savings alone, excluding anything you earn on exporting - you could possibly earn well over £20 a month.
Ultimately the reason to go for solar is to reduce your monthly bills, create a short/medium term investment for good returns in the long term, and ultimately be able to use electricity with the piece of mind that you're not contributing to carbon emissions or grid usage.
That said, 16k is very steep.
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I was thoroughly unimpressed by the Project Solar salesperson who came out to us, he was full snake oil.
They have huge referral incentives to exisiting customers.
There's a couple of people on here who have had their systems, you'll be able to search for their experiences.
In terms of tariff, Octopus or EDF Go at ~7.5p off-peak (now more expensive but should come down again soon) and British Gas Variable Seg at 6.4p kwh and a battery that covers most of your daily useage is the optimal in my view and makes an immersion diverter a waste of money since you can just use a timer instead.
They have huge referral incentives to exisiting customers.
There's a couple of people on here who have had their systems, you'll be able to search for their experiences.
In terms of tariff, Octopus or EDF Go at ~7.5p off-peak (now more expensive but should come down again soon) and British Gas Variable Seg at 6.4p kwh and a battery that covers most of your daily useage is the optimal in my view and makes an immersion diverter a waste of money since you can just use a timer instead.
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Project solar are pretty bad in my experience. I steered well away from them. I ended up with a local firm to me who were actually very good.
An immersion diverter isn't a waste of money since it can literally heat your water for nothing? Or am I missing something in your point?
An immersion diverter isn't a waste of money since it can literally heat your water for nothing? Or am I missing something in your point?
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