Maplins PV clearance

[mobbsey]

Maplins currently are clearing out their PV stock -- lots of stuff at 30% to 50% reductions! (just got one of their portable briefcase PVs for 50% off!)

[rs]

yep, I spent a small fortune in there the other day. Got the ?149 briefcase (13w panel,7ah batt,controller and two lights) for ?75 (think it should've been ?99 but i'm not complaining!).

Also picked up 3 of their 12w DC lighting kits for ?150 (normally 100 each) which I've got hooked up to my shed and happily working away even at 9.30 last night!)

I've got a couple of battery chargers hooked up via cigarette lighter sockets and they did a fine job of charging a batch of AA's yesterday.

Next job is to wire in my dc garden lights and buy a bigger battery.

Has anyone seen those morningstar sunlight controllers which has lighting timer built-in or one of these:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... =p3907.m29

[adam2]

In my experience maplins PV equipment tends to be at the lower end of the qaulity range.
Well worth considering though when heavily discounted as at present.

[Vortex]

Is their 60 watt amorphous panel good value at ?199?

[adam2]

Is their 60 watt amorphous panel good value at ?199?

Was it this one?
http://www.maplin.co.uk/module.aspx?Mod ... m6#specifi

The price is reasonable, but because the PV modules are amorphous, rather than crystaline, they are much larger for the power output, this may or may not matter, dependant on the application.

The glass is probably regular window glass, rather than the toughened or tempered glass used in better modules.

No long term warrenty is mentioned whereas the well known brands of PV module generally have a 20 or 25 year warrenty.

The price (which includes a charge controller, worth perhaps ?20) is however attractive compared to mainstream suppliers.

[Mitch]

I agree with Adam regards value for money, just beware of the "60 watts" though. What I call "Japanese watts" may be quite different to real watts. I have noticed that panel outputs are calculated every which way - except the "actual" value's. For example, 60 watts at 12v is an output of 5 anps. yet at 24 volts is an output of 2.5 amps. A panel could be rated at 50 watts, but this is calculated at the maximum current the panel can put out - say 2.7 amps - but at the highest voltage that it will still deliver the said 2.7 amps, say 18.5 volts. That panel would be rated at 18.5 x 2.7 = near enough 50 watts. In reality however, your battery system is 12 volts, and the panel can only produce 2.7 amps maximum, irrespective of the voltage, so you would only get 12 x 2.7 = 32.4 watts out of it. When calculating your requirements, it is best to divide all stated power values in half. In the "old day's", a 36 watt B.P. Solar panel really DID give you 3 amps at 12 volts!! Not any more! Today that same panel would be rated at 60 watts!

[adam2]

Its also worth noting that chinese watts are often subject to a large % tolerance, therefore a "60 watt" module may in the small print, be plus or minus 15% It will therefore be in fact a 51 watt module (60 watts less 15%)

Reputable manufacturers have either a much tighter tolerance, or warrant that every module will produce the claimed output.

[RenewableCandy]

I'm new to the process of actually buying any of this stuff (except a few battery chargers from the CAT which seem to be very disappointing). So can anyone point me in the direction of a supplier of "stuff that will fit together and do what it says on the tin"? Even if it's a bit costly?

[rs]

I'm new to the process of actually buying any of this stuff (except a few battery chargers from the CAT which seem to be very disappointing). So can anyone point me in the direction of a supplier of "stuff that will fit together and do what it says on the tin"? Even if it's a bit costly?

Do you have something specific in mind or just planning on having a tinker?

[Mitch]

Very difficult to find such a supplier - I tried being one a decade or so back and obviously never made any money, everyone else was supplying stuff that did twice more than mine, at half the price! ( I can buy car speakers that are 10 times more powerful AND half the size for much less at Maplin, they don't even HAVE magnets - let me know when you decide to stop ripping people off!) Best thing would be to properly measure and post your requirements. You will be sure to get truthful calculated responses from Power Switchers who have been there before!

[adam2]

I'm new to the process of actually buying any of this stuff (except a few battery chargers from the CAT which seem to be very disappointing). So can anyone point me in the direction of a supplier of "stuff that will fit together and do what it says on the tin"? Even if it's a bit costly?

I would be pleased to advise and perhaps recomend suppliers, what are you thinking of?

A small standalone pv system? to power what sort of loads?
Or portable equipment?

Even PV modules from reputable suppliers dont allways produce as much power as one would hope. They are rated in watts at the "maximum power point" The watts into a 12 volt battery will be less, and the watts that can be supplied from the battery still less owing to battery losses.

Batteries are rated in ampere hours, generally if deeply discharged over 20 or 100 hours.
In many applications the discharge will be over only a few hours and the capacity much less than the nameplate rating. In addition it is most unwise to routinely fully discharge a battery since it will shorten the life.
Therefore the practicle available capacity of a battery may be only 10% to 50% of the nameplate rating.

Invertors from reputable suppliers generally do what they say on the box. Cheaper ones are probably rated in chinese watts, for example 1,000 watt invertor can only supply this for 15 minutes, and at a room temperature below 18 degrees and with the battery voltage at 14 volts.
At a battery voltage of 11.5 volts, and a room temperature of 25 degrees, the 1,000 watt invertor can probably only supply 750 watts, and perhaps only 500 watts reliably.

[RenewableCandy]

I'm new to the process of actually buying any of this stuff (except a few battery chargers from the CAT which seem to be very disappointing). So can anyone point me in the direction of a supplier of "stuff that will fit together and do what it says on the tin"? Even if it's a bit costly?

Do you have something specific in mind or just planning on having a tinker?

Thinking of a system like the one described by adam2.

[adam2]

I'm new to the process of actually buying any of this stuff (except a few battery chargers from the CAT which seem to be very disappointing). So can anyone point me in the direction of a supplier of "stuff that will fit together and do what it says on the tin"? Even if it's a bit costly?

Do you have something specific in mind or just planning on having a tinker?

Thinking of a system like the one described by adam2.

I will add to the relevant thread, a list of suggested suppliers with prices etc.
http://www.powerswitch.org.uk/forum/vie ... 3626#73626

Feel free to add any enquiries re small pv systems to that thread

[rs]

what are people's thoughts on this page describing how to calculate solar requirements?

http://www.greenweld.co.uk/data/How%20t ... ements.pdf

Nicely explained in the figures are accurate?

[Mitch]

A long post, I know - but here's my experience of trying to supply my requirements, off grid and oil free.

I have everything one would normally have for daily living in a studio, or 1 bed flat. It's just that it's crammed into a 26ft x 6ft living space on my narrow boat. Although the smaller area obviously requires less heating energy. I have all electric cooking, but the hot water and room heating are diesel, more on that later. I measured my electricity consumption over a week and a month, averaged out, it was 9.7 and 9.5 Kw/h per day respectively. Let's say 10kw/h per day (24 hours) would do my electricity.
Due to financial and physical space constraints, I can only get 21 x 70 watt panels on the roof. In reality, I only expect around 720 watts per hour in good sunlight. If we really stretch it, and say we have 10 hours of sunlight a day in summer, this gives me about 7 kw/h a day - 30% short of my average requirement. In winter I can expect only about .9 Kw/h per day - 90% short of my average requirement! This kit cost 11 and a half grand! O.K., so the panels are semi-flexible/unbreakable etc and normal glass panels would be about 25 - 30% cheaper, but it's still damned expensive to get one tenth of my average requirement in winter! Which almost defeats the purpose. I would have to spend 10 times this amount and have 10 times the area, to just cover my requirements! Now this doesn't even take into consideration hot water or heating in winter. I have a 4 Kw diesel drip fire with a back boiler used for heating the hot water tank. Running this 24 hours a day in winter provides another 96 Kw/hrs per day!!! That is 10 times my electricity consumption! To cover my total energy requirement electrically in winter, I would need 100 times the kit I have bought! Sure, out goes the diesel fire and in with a solid fuel - but this will become a bit of a mission, having to make the fire in mid-summer just to get a hot bath. An electric immersion heater would take about another 5 Kw/hrs of electricity a day - and I don't even have enough as it is, without it! I calculated this by taking what the current fire delivers to the water tank - 3 kw, with 1 kw space heating. It takes 5 hours to bring the water tank to 70 degrees, from room temperature. That's 15 Kw/hrs. However, I would need only a third of this to keep the water hot, once it's up to temperature, so 5 Kw/hrs a day.
As you can see, be prepared for a rude awakening if you are looking at substituting renewable/green off grid energy for your electric/gas/fuel requirements!! We haven't even touched on the battery banks, inverters, regulators etc that are required.