One of my lads has just asked me to comment on these
Maybe of some use if you live somewhere near the equator? Brian
Have you/they accounted for the fact that in the UK, the over-all capacity factor for solar panels is about 15% at best, often closer to
10% and about 5% in winter?
ISTR you're north-east ish?
Between now and February, the panels will probably give you ~1kWh per day, so only enough to 1/4 fill the battery daily.
Do you need the 230V? If it's just lighting I'd run it direct off the batteries instead of the inverter (either 1x24V or 2x12V strings of LEDs) how many Watts of LEDs, for how many hours per day, or week?
That is clever thinking!
And you can also get 12V B22 LEDs. No idea if they are legal other than on traveller sites.
the trouble is with dropping the supply voltage, that for the same wattage of lighting, the current has to increase. This means that the CSA of teh wiring must also be increased and there is also higher P= I2R power loss in the cables.
This has to be balanced between the conversion losses in the inverter.
See if they can customise the kit for you to have twice the panels, half the batteries and no inverter?
Andy's suggestion did away with the inverter.
Sorry, I unintentionally started a hare running by mentioning stables. My lad was after something to run lights and a freezer in an industrial unit without power, but caught by the line "higher power generation.....workshops...." etc. We do indeed supply our stables from batteries, using 12 volt B22 and E27 LED lights, but these are discarded car and lorry batteries and a couple of leisures charged from mains at home. I mentioned stables in my first response to him because he knows the scale of our operation. Batteries run the electric fencers, lights in the winter (or emergency lighting after dark in the summer) and that is it. The kettle runs on Calor, power tools are all cordless with an inverter genny for bigger tools or other emergencies.
No, he's after mains, principally for a freezer but also for a small workshop space.
That was my thought. These are of course smaller panels than the usual domestic ones (130W rather than 330W). Typical domestic installations seem to be ~£4kW peak for £6k. I think the ad is pretending to be something it is not.
Biggest problem, I doubt a 1kW inverter will reliably start the compressor of a freezer.
A domestic chest freezer E rated (new "E" is the old "A++") would consume over
200 kWh/year, that's 20% of the panel's daily averaged output, somewhat conveniently it'll take more cooling in summer when it's sunnier.But there might not be much left in the battery for lighting during the winter months.
How can a lamp bulb be [il]legal?
I have a 500 watt inverter that quite happily starts and runs a standard domestic fridge (under counter size) so I'd expect a 1kW inverter to cope with most freezers OK.
This is off-grid I presume?
I mean it depends how much hassle you want, but personally I'd look at getting some used solar panels and a used inverter. You might be able to pick them up for cheap. The solar charge controller there looks like a £30 job which you could pick up from ebay.
Personally I'd also be tempted to look at a lithium iron phosphate pack build, which are about $130-180/kWh delivered out of China these days (if you dodge the scammy sellers) plus $60-100 for a decent BMS. Although if you don't have a lot of roof area the difference might not be worth it.
Theo
Interesting points, thanks, I will pass them on. I already suggested that he might do better buying second hand panels and perhaps mating them to something like a Tesla powerwall.
As high as that? My year round figure is 8.6% based om 8766 hours in an average year.
Maybe, but it looks like a pretty cheap "1kW" inverter
I was hoping to get some real data like this. I'd be interested to hear suggestions of useful/realistic data sources from those who actually have panels.
FWIW every time I have done the sums in the past I have found that a pair of SLA lead acid accumulators (and a charger that I already have) can beat any off grid solar panel based solution hands down. It is changing slowly but you have to be very off grid for it to work!
Provided that is you don't have to carry the batteries too far and you can have a battery capacity that will last a week or so.
It is worth looking at the options very carefully. The one where solar panels might sometimes win is for summer use electrical gear like my stone mason friends intermittent use forklift truck. He might (eventually) get a payback from installing a solar panel on that.
The active radar "please go round the bend" signs near me are already beginning to fail by 11pm and we are only just into November. Worse the weather hasn't been particularly bad yet. They kill their batteries every winter without fail and are never working on a frosty winters morning when they might just possibly do some good.
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