I very nearly bid on a Grid Tie inverter on ebay today that you may have been bidding on, If I had managed to bid quickly enough I may have won it. My maximum bid was higher than the winning bid by 27p :-) but the winner managed to get their bid in a few seconds before mine and mine wasn't high enough to make it to the next bid increment and so was rejected.
If we are all going to be bidding on these things we should co-ordinate so that we don't put the price up on each other, or if we had enough people to put in a bulk buy to the manufacturers.
We have a digital pay as you go type of meter so I'm pretty sure it isn't going to go backwards, but as long as it slows down I'll be happy. Anyway I doubt i'll have the money to buy enough panels to cover all of our electric for quite a while anyway. I hope to move house when I can afford to so maybe the new place will have that type of setup.
As for the bulk buy thing, if we were buying from the manufacturers there would need to either be a lot of us to make it worthwhile or maybe buying them to sell on. A lot of the chinese manufacturers seem to sell in small quantities, but I haven't asked them for any prices yet.
I saw this on ebay - tinyurl.com/crarv4n Three Inverters and 6 panels, so good for two or three people to buy and split up, currently sitting at £320 and courier would probably be another £100 - £150.
i have a 360w Gt inverter with only 80watt peak of panels at present and it's been running for about a month maybe.
if i didn't know any better i'd be disappointed with the performance in poor weather,but i will explain further. the inverter uses mppt, i.e., maximum power point tracking. i think this means that it cleverly and continually varies the load that the panels 'see' to extract the max power available from the panels. however, i'm guessing it has a set number of available loads it uses and these are designed for 360w worth of panels not 80w worth of panels. so the mppt is not performing in poor light / dull days as it should because i haven't enough wattage.
on bright days i am getting 200-300wh from the current setup. the panels are shaded for part of the day too which does not help.
i have experimented with manual tracking, i.e., intermittently moving the panels so they're facing the sun, and it makes an enormous difference. my guess is that with automated tracking i would get significantly better performance.
i had initially read that tracking gives up to an extra 40%, but i think the difference may be even greater in this climate. i'll post a link up shortly to a european study on tracking, which seems to suggest that one can achieve 1000kwh per kwpeak per annum in ireland when tracking is used. the rule of thumb for fixed pv in uk is 500-600kwh pa per kwp. good news is that single axis tracking is very much more than half as good as twin axis tracking.
Post by silverback02 on May 29, 2012 12:19:59 GMT -5
I've just found this forum (Today) and so far I've been very intereseted in what ppl have to say. First I'll tell you about me and then what I am interested in trying to do to my place.
I am Joe, and I live in Bangor Co Down. living with my missis, 2 dogs and 2 cats, in our "Chalet" type bungalow. (Fancy name for a bungalow with an upstairs conversion...lol)
Due to my electric bills bieng on the stupid high side, and my kids (Allthough all left) going on about Green Energy ect, I decided to look into the following.
1. Photovoltic electric panels, To offset the high leccy bills, 2. Pv thermal for my domestic hot water, (The two of us don't need too much, until kids & Grand kids arrive) 3. An A.S.H.P. to take over as much of my heating as possible, just useing the oil as a back up.
As with most ppl, the first thing I did was to get the companies out to give me quotes on the various systems, When I recovered from the series of heart attacks these prices gave me, I decided to look into doing things on the cheep. I.E. Either buying PV panels off Ebay along with other bits to get it up and running legally, and then adding panels that I've made up myself (Good with a soldering iron !!) Looking up on how to make my own Thermal Flat Panel useing either Copper Pipes and a Heat collector, or an old large panel radiator enclosed in a sealed collector. I think the Air Souce Heat Pump might end up bieng the expensive bit. But I shall see. Up too press I have managed to get 4 x 175w Pv Panels of the bay and was given a 200w Panel as a spare. I am just wondering, What would the best way to wire them up, to get the best out of them. Any suggestions of what inverter I should get and what output I should expect. All info will be greatly appreciated. cheers for now, Joe.
I do not pretend to be any sort of expert in pv but here's what i think needs considered to get the conversation started. (you will see that i am presenting only a meandering series of options with some pros and cons noted!):
if you have different makes/models of pv panels do not put them in a series string. The general guidance is that anything in a series string (where voltages are combined rather than currents) all needs to be the same model of panel. so your 200w panel will have to go in parallel with whatever else you have as a start.
assuming your first ebay lot of panels are all the same model, then whilst in theory you could hook this lot up in a series string, you would be adding voltage rather than current. if all your panels are 24v then 4 of these in series will give you around 100v. now consider what happens if this series string of four is then hooked up in parallel with your other 24v panel (the 200w panel) - it's not a good idea either to parallel up 'panels' or panel strings of different voltages, so that's not viable either (i think).
it seems to me that, assuming all your panels are 24v, the simplest arrangement would be to put them all in parallel, with each one protected from reverse current by a suitably rated schottky diode (blocking diode). with 5 panels of 24v each you'll have a 24v output and you'll need a grid tie inverter (GTI)suitable for 24v and 900w-1kw peak. whilst this spec of GTI may be available, most of the 1kw GTI s have a minimum spec of 48v but do check the specs.
now, this leads me to think about the maximum power point tracking feature of most efficient GTIs. This mppt feature is less likely to work well with a mix of panel makes as each make/model behaves differently in different light, so the mppt will only ever end up finding an average 'sweet spot'.
all this leads me to think that, if your panels are all 24v, you should go for a larger number of smaller mppt GTIs. the ones that are rated for 24v panels and 360-400w rating. put pairs of panels in parallel, and one pair per GTI. one of your pairs will be a mix of 200w and 175 w but these are close enough to parallel up.
Post by silverback02 on Jun 7, 2012 8:59:39 GMT -5
Hi Cye, Thanks for that, you have confirmed what I suspected, in that I can only link the four Topsola 175W panels together, and as these panels are rated at 175W, open circuit volts 44.3v, max power 35.8v, short circuit current 5.3a, & max power 4.89a. in series that would give 700W, 144V, 4.86a Parallel = 35.8V, 700W, 19A, or 2x2 in series & Parallel = 71.6V, 350W, 4.8a twice resulting in 71.6V, 700W, 9.6A. Am I correct in those figures ? and if so am I also right in saying you would go for the latter (2X2). what would be the best inverter for that setup then ?
As for my fifth panel a ZNSHINESOLAR 200W, max power 37.2v, max power 5.38A, I am thinking of useing that to power a 12v hot water pump simular / same as this www.ebay.co.uk............................ pt=UK_Sound_Vision_Other&hash=item1e6e76c181 which you might recognise, (and where I found this site from) or a hot water immersion heater simular to this, www.ebay.co.uk/itm/150363487613?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 What do you think I could do with that ? Again thanks allready and all info will be greatly appreciated. cheers, Joe. Ps, how / is there a way I can automatically receive notification by email when someone answers a post I'm interested in so that I don't miss any ? cos I havn't found the right button yet. cheers.
the pv pump you referred to is unsuitable for your panel because the voltage range required is 6v-24v, and your open circuit voltage well exceeds this. Also it does not make great use of what you've got to be considering running a 10-15w pump from a 200w panel. (i've removed the link to the pump in your post because i do not wish to use this forum in a manner which may be misconstrued as for personal benefit, hope you don't mind. i have no qualms about pointing people from an eBay ad to the forum as it's good for the forum, but i don't want it to work the other way around!)
i am no expert on GT inverters, and i suggest, as a start, you review the specs of a few on eBay.
If you want to go strictly legal, the budget end of G83 inverters are the StecaGrid and the MasterVolt Soladin inverters available from about £200 and £300 upwards respectively.
For less money you should look at the Chinese inverters and that's a matter of reading the specs and checking eBay and other user feedback. a guy in glenavy recommended ebay vendor lensunsolar2010 and i bought a small GT inverter from them - perhaps worth a look at their larger stuff.
Heating water from PV is not the best use of your 200W PV panel. PV is at best 18% efficient whereas solar thermal panels are significantly more efficient. if you do not want to use your 200w panel for GT, why not get a charge controller and a deep cycle battery and run a few rooms worth of led lighting in house from it?
there's a guy in carrick who sells refurbished deep cycle Trojan batteries . I'm thinking of getting one or two for just such a lighting project.
his gumtree ad is now gone but i still had his details.
john thomspon, operates a golf cart battery reconditioning service from curran business park in larne (sorry, not carrick)
02828 260951 or mobile 07860 914663
now i haven't spoken to this guy, but i would be interested in joining you with a purchase of a few of these and it may be worth a joint approach. i want to start running the led lights in my house on pv.
he was selling Trojan T105 batteries which are true flooded deep cycle batteries. you'd need a minimum of 2 of these for a 12v setup as these are 6v each.
Post by silverback02 on Jun 11, 2012 21:23:55 GMT -5
Hi Cye, Thanks for all the info, and I'm sorry if I broke the rules about the ebay listing, (Naught joe), Anyway I was reading other DIY Solar Thermal panels projects within these forums, and found someone used a Plate Heat Exchanger with their panel. I was considering a Willis type of exchanger, but the cost put me off. So I ask, Can Any of the P.H.E.s advertised on the bay do the job ? (Provided 4 port). I would be using this in conjunction with my home made panel and pump. (Very simular to the post, DIY in Bangor). again Cheers, Joe.
not so much you breaking rules on posting links, the off ebay link is fine, but rather that i was not wanting to have a link on this forum to something i personally was selling on eBay, and that i did not want to be using the forum to promote anything that would potentially benefit me personally.
all PHEs are not necessarily alike. you will need a 10 plate HE. best advice i can give is to use something that we know works for sure, i.e., the model of PHE used by both dermot leonard (see the galway solar thread on this forum) and by wookey in england (google "wookey + solar" to find wookey's website). i think these can be had for £60-80.
I have heard of that chap before, I think he runs a haulage company and as far as I know he runs/owns the Curran Industrial Estate. I have also heard his name in connection with a few other things. First time in connection with batteries though.
I will give them a call and see what they say and get a few prices. I'll report back and let you know what they say.
My main interest in batteries is for powering an electric car, a wee project I am working on (early days yet), I'm not sure if these batteries will be OK but it's worth a go.
Here are a few pics of my efforts. These are the first 4 of 16 50 watt monocrystaline panels I plan to install. The 4 are rivited to an aluminium frame (old greenhouse door) and the IBC upon which they are mounted was intended to be a temporary arrangement. but I can see advantages with the idea. 1, It is a good height to keep the panels above vegation but not so high as to make cleaning them a chore. 2, Filled with water, even the winds of Connemara will not throw it over. 3, It would not be difficult to mount a tracker on the IBC frame.