sunny solutions

Solar panel array to run Koi pond pumps

2009-04-09T09:22:00.001+01:00

I wish to use solar power to run my koi pond,have been on your solar calculator,and it tells me that i am using 4920 watts per day(pond pump 150 watts 24 hours aday)(air pump 40 watts 24 hours a day)uv light 15 watts 24 hours aday)
what kind of system would i need.many thanks mark

Unfortunately, you would need a huge system to run that - those are fairly powerful pumps, and if they are on all the time they are using a lot of electricity (as you've probably noticed from your electricity bill!).

On an average British day, the power you need could be produced by a solar panel array of approximately 2000 watts. However, you do of course get more power in the middle of summer than in winter. In summer you could produce that power with about 1000 watts of solar panels. In winter you would need nearer 5000 watts of panels to produce enough power.

1000W of solar panels cost the best part of £5000, so even in the middle of summer it would be a very expensive solution!

Sorry not to be able to be more encouraging.

Cheap solar system for van

2009-04-02T09:35:00.001+01:00

hi guys, hope all is well at midsummer, i wonder if you could help? ive just bought a van to live in for the summer and would like to have solar panels to provide electric, i only really want to run some tunes (small sound system) and my laptop. if you could advise on the best (and cheapest)set up i would be very greateful,
many thanks and blessings alex

Hi Alex,

A lot depends on how many hours a day you need to be able to power your laptop and sound system! Laptops can be quite power hungry. However, assuming it's no more than a couple of hours a day, in the summer you can still get away with a fairly small panel. I would go for something like a Kyocera 50W solar panel kit as a minimum; if you can afford a 65W or 85W kit, then they will give you a fair bit more power.

The kits come with solar regulators and all the wiring you need. You will obviously need a battery - if there isn't a domestic battery already in the van the Elecsol batteries are excellent. That should be everything... unless of course you need 240V power as well as 12V, in which case one of the budget Silverline inverters will give you that.

hope that helps, and enjoy the summer!

Amorphous or crystalline - which is a better solar panel for a narrowboat?

2009-02-27T08:57:00.001Z

Hi, we live on a narrowboat (currently on a Winter mooring in Paddington basin) & have been looking around at alternative energy sources for a while. I'm interested in either the Unisolar ES62 (probably x2) or Kyocera 130. It seems the amorphous are probably better suited for UK conditions but I'd be interested to know your opinion on which would be better for our application.

We currently charge via the engine & have 4 x 270Ah batteries & a Sterling regulator but before I get into figuring out what extras I would need, I have to decide on which type is best for us.

Regards, Allan

Hi Allan,

In terms of output there is not a great deal to choose between the two types. You will get slightly better performance from the ES62's in overcast light - perhaps overall about 10% more power per watt rating over the course of the year.

On the other hand, the KC130 is slightly more than double the ES62's rating anyway, so it does make very little difference overall.

There are two other differences to consider when making your decision. Firstly, the ES62s have a plastic coated front, rather than glass, which makes them a little less susceptible to vandalism (though having said that, the KC130s use toughened glass and damage is really very rare). Secondly, the amorphous panels are considerably larger for a given power output compared to crystalline panels. A single ES62 panel is only fractionally smaller than a single KC130 panel - so if space is at a premium on your roof, the KC130 might be better.

Hope that helps. To be honest I think you will find either type works very well, and it will be lovely not having to charge from the engine all the time!

12V lights for catering trailer

2009-02-18T08:56:00.002Z

I need a 12v replacement for my catering trailer which is usually lit by a 1.5m fluorescent mains light. Will an LED strip give me enough light? Tony.

Hi Tony,

You would need quite a lot of LED lights to give you the same brightness. You might be better (and a lot cheaper) going for 12V fluorescents such as the Trilite 24W. Depending on the size of the trailer you might need several units to give you the same brightness as your original light. If you can find the power of your current light, in watts (it's likely to be on a sticker on it somewhere), you will need about the same wattage in 12V lights to give the same light output.

Andy
Midsummer Energy

Does a regulator stop reverse current at night?

2009-02-16T10:12:00.002Z

Just another quick question about the solar panel that I've now got bolted to my roof. You've probably been asked this load of times before, but just to clarify - does the panel drain the batteries at night? According to my battery monitor, I am losing some power overnight (a few percent of the charge according to the Smartgauge) - I don't know if this is because the power is actually leaking back through the panel, or because the batteries are just settling down somehow (obviously, I've got no idea about the technicalities behind all this). Is the regulator supposed to act as a diode to prevent this, or should a separate diode be fitted between the regulatorand the batteries?

Thanks, Jon

You don't need a diode when there is a regulator - it stops any power leaking back through the panel.

Batteries do slowly self-discharge of their own accord, so you would expect the charge to drop a small amount overnight. As long as it's only a few percent there is nothing to worry about. If it's a significant amount, either your batteries are getting old and tired and losing charge more quickly - or there is something else draining power on the circuit.

However, it certainly shouldn't be the solar panel draining power if it's going through a regulator - that should prevent any reverse current.

Andy, Midsummer Energy

Running a radiator from a PV panel

2009-01-30T14:25:00.001Z

Hi - I have a studio in my garden, it is 3.5 m x 7.5 metres. It has electricity, but I want to keep it moderately warm (i.e. above reezing) because I have computer equipment in it (for day time use I have an oil run radiator). A friend suggested a solar panel to keep a small radiator ticking over. I don't have a huge budget, is this something I could do at a reasonable cost? Thanks. Sam.

Basically, no. It would be an extremely expensive way of providing heat!

Doing a few quick calculations on our solar panel calculator: a 500W electric heater (which isn't much), on for 4 hours a day, needs 3000Wh of electricity. Even in summer you would need 600 watts of solar panels - which would set you back about £3000. In winter, when you presumably need the heat, you would need an array five times as big.

If you've got electricity there already, you're far better off using mains for the heating - if you want to make savings, spend some money on improving the insulation!

Andy
Midsummer Energy

Recharging a 24V electric scooter with solar panels

2009-01-27T10:09:00.001Z

Hello.
I have an electric scooter that I use to make the 8.5 kilometer journey to work.
The 24v battery is rechargeable and takes 3.5 hours to recharge from the mains with a power supply.
What I would like to know is: can I use a small solar panel to recharge outdoors for longer journeys?

Thank you. Jeremy.

Most solar panels are designed for charging 12V batteries. However, it is easy to charge 24V batteries simply by wiring 2 solar panels in series.

So yes, it would be relatively easy to add some solar panels to give some additional charging of the battery. However, you would have to do your sums and work out just how big a pair of solar panels you would need for the system to be effective! If you had say 100W of solar panels (a fairly big area), that would still only give around 20Ah at 24V on a summers day. They would unfortunately be probably too big to carry around on an electric scooter....

Andy - Midsummer Energy

Solar panel for motor sailer

2009-01-26T10:38:00.001Z

I own a motor sailer with two 12v 110ah batteries in parallel i.e 12v 220ah. What size solar panel do you recommend and which regulator? The batteries supply all we need when fully charged so we are looking just to top up the batteries over a few days or so. Do we need to disconnect the panel when we use the engine and what else would we need.
regards Alan

Hi Alan,

If all you are looking for is a panel to keep the batteries topped up to keep them in good condition when you are away from the boat, then something like the Spectra 20 would be ideal, with a Sunguard regulator.

A 20W panel will give you about 8Ah per day in summer - although considerably less in the winter. So it will slowly recharge the batteries if you are away from the boat for a while. However, if you think you need to recharge batteries faster between uses, then you could go for a bigger panel. One of the Kyocera range of solar panels would be a good choice - they are available as solar panel kits with appropriate regulators included.

There is no need to disconnect the solar panel when the engine is running - the regulators are designed to work in parallel with other charging sources. Apart from the solar panel and regulator, all you need is some wire to connect them up! A fuse in the line is a good safety precaution - in many cases you can wire it up to an existing fuseboard.

Andy - Midsummer Energy

30W solar panel to power a house?

2009-01-21T09:38:00.001Z

Hi, have been trying to work out what type of solar setup I would need to run my house hold purely from solar, the best way I could work out my daily consumption was to record my electric meter usage, this equates to max 15wh does this mean I could run my electric from one 30w panel, 4amp charge controller and 12ah deep cycle battery? Would be glad of your input, many thanks.

Looking at your meter is certainly a good way of working out your needs. But unless you have an extraordinarily energy-efficient household it's probably reading 15kWh per day, not Wh. That's 1000 times as much.

Most households need about 4000W of solar panels provide enough power to meet their needs - a 30W solar panel won't do much more than power a single low-energy lightbulb for a couple of hours a day!

best wishes,
Andy
Midsummer Energy

Sizing a solar panel for lighting a stable block

2008-12-01T08:39:00.001Z

I am running two Lumina 18w lights in my stables powered from one 85amp leisure battery. I am charging from the mains when the battery needs recharging. Can you please advise what size & type of solar panel, regulator etc I would need to keep the battery charged. I also run an electric fence from a second 85 amp leisure battery which is situated behind the stables. Could I put the two batteries together, use one solar panel and run both applications? Regards, Wendy

Hi Wendy,

It all depends how many hours a day you use the lights! If we assume 1 hour a day every day, that's 18 watts x 2 lights x 1 hour, or 36 watt-hours per day that you need to generate from the panels. In summer you could generate that much power from a very small panel - even a 10W panel (such as perhaps the Spectra 10W panel, with a Sunguard regulator).

In the winter, you would need something bigger - but I think a 40W panel should be sufficient even in the depths of winter. In that case you would be best going for the 40W solar panel kit, which includes a 40W Kyocera panel and a Sunguard regulator, and all the wiring you need.

If you use the lights for more than one hour a day on average, you would need a bigger panel in proportion. If less than one hour, you can go smaller with your panel.

Yes, it would make a lot of sense to put the two batteries together and run both the electric fence and the lights from the one bank. Electric fences don't use much power - I think you would be able to run both the fence and the lights from a 40W panel. Very easy to do - you just wire the two batteries in parallel, with the two positive terminals joined by a lead, and the two negative terminals joined with another lead.

best wishes, Andy, Midsummer Energy

Solar panels and inverter for narrowboat

2008-11-26T15:07:00.001Z

Hi Andy,

Having had a good look around your website, I'm hoping you could give me a bit of advice about renewable energy options, as a novice narrowboat owner who knows very little about boat electrics – so please forgive my ignorance!

Firstly, generating electricity – battery-wise, we've got 3 new domestic batteries connected to an Adverc system, and I'd like to be able to charge these without having to use a separate generator. I was therefore thinking of investing in a sizeable solar array, maybe a single 130w Kyocera panel, or a couple of 65w panels, plus a controller. I'd just like a very rough idea of whether or not this would provide a reasonable amount of power for us, living aboard, without having to run the engine all the time, or whether we should be thinking of investing in a larger array? I know that this is a difficult question to answer without knowing the specifics, but basically, we're not planning to use the fridge over the winter (we've been told that they use a lot of power), so it'll basically be running the lights, water pumps and TV / stereo in the evenings and at weekends over the winter, and then the fridge as well in the spring / summer (when I presume we'll be getting more power, as the light levels increase). We're likely to be cruising most weekends, so we'll be generating power from the engine on a fairly regular basis. Do you reckon the combination of solar panels and sporadic engine-use is likely to be sufficient, providing we're careful with our power usage, or is it inevitable that we'll end up needing a generator of some sort, as some people seem to think?

Secondly, using appliances – we've got a 650w inverter on the boat at the moment, but I'm thinking of upgrading to a 1000w Silverline model. There are 240v sockets down one side of the boat and an external hook-up socket for shore power. It's been suggested that we should just use this system for our normal appliances, rather than muck about with wiring things into the 12v system. We're not going to have a shore hook-up, so it seems that we're going to need to have an inverter more or less permanently connected to the battery bank, with a lead running outside to plug into the external socket, to power up the internal 240v sockets. I'd just like your opinion of whether or not this sounds like a sensible and safe way of doing things – specifically, how efficient are inverters? Are we likely to be losing a lot of power by running our appliances like this? Also, is it safe and efficient to have an inverter permanently connected to the batteries like this – do they still draw power when nothing is connected to them, and do they get hot after prolonged usage? I'm guessing that the unit is designed to just cut-out if overloaded with too many appliances (although we're not planning to run anything more heavy-duty than e.g. a TV and DVD player off it).

Lastly, I'm assuming that all of this stuff is pretty easy to install and connect up to the batteries? At the moment, I'm at the bottom of a pretty steep learning-curve when it comes to most things related to boat maintenance, but I think I can cope with a bit of very basic electrical DIY.

Any advice would be very much appreciated!

Many thanks, Jon

Hi Jon,

It's certainly possible to run narrowboat electrics all through the year just from solar panels - I manage it on my own boat! That said, even with a biggish array (about 200W) I do have to be pretty careful in winter to keep usage down.

I would think a 130W panel would be a good choice based on what you expect to run. That would certainly have no problem at all in keeping up with lights, water pump and stereo use (though having energy efficient fluorescent or LED lights is well worthwhile to make sure of that). Fridges and TV do take a lot more power - but if you are happy to turn your fridge off in the winter, and are also able to get a bit of charging from the engine at weekends, I would think a 130W panel would be ample 90 or 95% of the time. Just occasionally if you are using systems heavily, and have a few overcast days, you might have to turn on the engine to charge - but I would think that would be rare.

Inverters are about 90-95% efficient, and draw a pretty low current when nothing is connected, so yes, they can be a sensible way of running appliances. It's no problem to leave them on all the time, and they do have thermal cut-outs if you do ask too much of them. I run a 240V fridge in summer for example - it was about 1/3 the cost of the equivalent 12V version, it means I can get away with thinner wiring, and there is little difference in the power it draws.

Wiring of a solar panel is extremely simple - two wires from the solar panel to the regulator, and two from the regulator to the battery. An easy DIY job. Wiring an inverter is equally easy - two big fat wires from the inverter to the battery. Having said that, they are 240V appliances, so if you are then wiring the inverter into a distribution system, you might want to have someone qualified to make sure it's all safe. Also, running a cable outside from the inverter, to then bring it in again through your shore power inlet is perhaps not the neatest way of doing things - it shouldn't be hard to simply rewire your distribution system direct to your inverter.

hope that helps, Andy

Losing charge through a Sunsaver controller?

2008-09-24T09:13:00.001+01:00

Andy I think the Morningstar SunSaver solar regulator SS10 is draining my batteries at night. Every night I read the volts on the solar side -.04, -.09, -.16 ; No load on 2 x 85amp leisure Batteries in parellel. Batteries increase around .25 volts a day and topped out at 13.29 yesterday night then dropped to 13.09 tonight.

What's your verdict?

What are the best batteries to use with the Kyocera 130 watt solar panel?

best regards, Scott

Hi Scott,

If they are only dropping to 13.09V there is nothing to worry about! Anything above 12.8V for a 12V battery is basically as fully charged as you can get it. Although the voltage will rise slightly above that during the day while charging is happening, it's quite natural for it to settle slightly overnight even if there is no load on the battery. If it was going down to 12.5 or so without any load on the batteries I would think there was a problem - but over 13 is a very healthy battery!

You do always measure a small negative voltage on the solar terminals when they are not receiving charge - if you actually measure the current along that wire however you should find it is negligible.

Standard leisure batteries like you are using are absolutely fine for use with that panel. They should last at around 5 years or so if they are kept well charged - which it sounds like yours are. 'Sealed' or 'gel' batteries would last longer - but they are so much more expensive that it's not really worth it.

A bank of 2 85Ah batteries is fine, but on the smaller end of the bank size I would recommend - you could easily add another couple of batteries if you want to have a bit more reserve for times when you are using the power heavily.

Hope that helps,

all the best,
Andy

Variation of output with mounting angle

2008-09-11T10:41:00.001+01:00

Where can I see a chart/graph showing the relationship between solar incidence angle and current output for a solar panel. I am interested in the BP380 but I assume that most units are similar. I am trying to assess the need for providing a tilt mount.
Thank you. Edward.

Hi Edward,

http://www.yourhome.gov.au/technical/fs67.html is quite useful, particularly the graph that shows the variation of solar panel output with orientation and tilt angle. The figures are for Australian latitudes - but you can get the idea at least!

Solar panels do give pretty good output even when not angled directly towards the sun. The graph shows that, for 35 degrees latitude, the optimum angle is 35 degrees (not surprisingly) but a horizontal panel will still be around 85% efficient, and a vertical panel will still be around 65% efficient.

Note that the difference is smaller during overcast conditions, when light is scattered anyway. At those times, there is practically no difference in output between a panel mounted horizontally, and one mounted at the optimum angle.

There is a graph of optimum angles for solar panels across Europe on our information site.

regards,
Andy
Midsummer Energy

Can you charge a 24V system with a single 12V solar panel?

2008-08-26T08:53:00.004+01:00

Is it possible to use 1 solar panel to charge 2 12volt batteries connected in series (24 volt) via 2 seperate 12 volt charge controllers, one linked to each battery? - Richard

Unfortunately, no.

The negative solar and negative battery terminal on most charge controllers are connected together internally - it's only for convenience that they provide you with two seperate terminals to connect the wire.

If you were to try putting two controllers in series, you would be joining the positive battery terminal of the first charge controller to the negative battery terminal of the second. If you then attach the negative solar panel lead to both solar negative terminals you have the following situation:

1) positive battery terminal of first controller is connected to negative battery terminal of second...
2) ... which is connected internally to the negative solar terminal
3) ... which is connected to the negative solar panel lead
4) ... which is connected to the negative solar terminal of the first charge controller
5) ... which is connected internally to the negative battery terminal

In short, you've connected the battery positive to the battery negative. That's called a short circuit, which is a cause of wires melting, fire, grieving next of kin etc etc.

If you must try it, I'd recommend making your will first. I can't see any reason why you couldn't put two 12V controllers in series with seperate solar panels, though don't take my word for it. However, it's more usual to simply wire two 12V panels in series to a single 24V controller. See our handy 24V solar panel wiring diagram.

Solar panels for yacht in the Med

2008-08-20T09:16:00.001+01:00

Hello
Can you help me with some advice on solar panels. I have a yacht based in the Eastern Mediterrian, it has 3x 155amp/hr domestic batteries and a seperate engine batterry. I'm looking to try and keep the domestic batterries charged whilst sailing and at anchor. The main power user is the fridge which uses about 50amp hrs per 24hrs.
Currently I have a Sterling Power Management system which displays the battery position and amps being used and total amps consumed. This system counts down amps when on charge either by engine or mains charge.
To start with I plan hang them on the guard rail.
What would you recommend? Regards, Martin

Hi Martin,

Fridges do consume a lot of power unfortunately, so you would need a reasonable array of solar panels to replace what the fridge is using. As a guide, in the UK summer you would need about 120 watts of solar panels to generate about 50Ah per day (assuming you have a 12V system). As on a yacht it is difficult to keep the panels always pointing towards the sun, you may get a little less than that.

I would recommend perhaps a pair of Kyocera KC65 or KC85 panels http://midsummerenergy.co.uk/buy_solar_panels/kyocera_framed_solar_panels.html. They should certainly deliver most of the power you need for your system - perhaps not all, but then again you will be getting some power from the engine anyway from time to time. Dimensions are on the datasheets linked from the product pages on the website. We can supply the most appropriate regulator and suitable cables too.

Alternatively, we can get in some Sunware solar panels which can be attached directly to the deck, and can be walked on. They are rather more expensive than the framed panels, but if they would be of interest do let us know.

best wishes, Andy, Midsummer Energy

Dehumidifier powered by solar array and micro hydro

2008-08-20T08:29:00.001+01:00

I have an isolated house in the middle of France 750m above sea level in a very damp location but with a south facing garden. The house is unoccupied for long periods of time and I want to install equipment to maintain low level heating and ventilation throughout the four story building to reduce damp and consequently woodworm activity. There is plenty of strong intermittent sunlight in summer, however in autumn and winter I have access to the overflow from a dammed lake that gushes water - I'd like to set up a microgenerator and connect this to the batteries thereby charging them through solar power in summer and water power in winter. If you have time to provide any tips I would be most grateful. Thanks, Malcolm

Hi Malcolm. It sounds a great little project - but whether it would be practical I'm not so sure! The trouble is that heating and dehumidifying equipment is very power hungry, and you would need a very large (and hence expensive) solar array to provide enough power. The best thing to do would be to find out the power consumption of the equipment you want to run, and use our solar panel calculator to work out how big a solar array you need.

A little micro-hydro turbine may in fact be a cheaper way of generating electricity, as you are lucky enough to have a suitable location! See http://www.homepower.com/basics/hydro/ for a useful guide. Navitron sell small turbines which might be suitable. regards, Andy, Midsummer Energy

Solar and wind power for summerhouse

2008-08-12T12:30:00.001+01:00

I have a summerhouse at the end of my garden and would like to power it with a combination of solar panels and wind turbine, hopefully through the same controller. I might want to use computer, stereo CD/radio,two lamps, perhaps 75w soldering iron - probably not all at once but possibly several at one time. Could you give me some idea what wattage solar panel, size of wind generator, and number of batteries I would need? Many thanks - Jenny

Hi Jenny,

A lot depends on just how often you want to use the equipment there! There is a world of difference between a big desktop computer and all the peripherals being used for a few hours a day, and a small laptop used occasionally for an hour or two.

You may find our solar panel calculator useful for working out how much power you would need.

However, a suitable system might include:

Rutland 503 wind turbine
Kyocera KC65 solar panel
HRSi regulator
100Ah leisure battery (available from any motoring store, eg Halfords)
2 x Labcraft Trilite 16W lights
500W inverter (if you would like 240V power as well as 12V)

That would be sufficient for a few hours of lighting and radio use a day; and perhaps say an hour or so a day of laptop / soldering iron use (more in summer, less in winter).

One word of warning about wind turbines - the output does depend very much on the location. If you have many trees around that cause turbulence and restrict the free flow of wind to the turbine, you might be better off going for two solar panels instead!

If the summerhouse isn't used regularly - and mainly in summer - even a single solar panel may be enough for your needs. It is easy to add further panels, batteries, or a turbine to increase the system size when you want to expand the system in the future - so you can always start small and increase as necessary.

Do hope that helps.

Andy
Midsummer Energy

Solar powered laptops - how much power do they need?

2008-08-12T10:02:00.001+01:00

Hi Andy,
I want to run 2 possibly 3 laptops off solar instead of using the power chargers all the time. 2 of them are on about 18 hours a day and all the time off powerpack. If I've used your calc pages properly for one laptop I would need a 1700 w panel to give 138 amphrs for a 12 v system. Surely this isn't right is it? The chargers / power packs are 19v and 4.74 amps and the laptop is on 18 hrs a day. Would it be better to buy an inverter?

P.S. Just wait, it won't be long before the term "Alternative energy" applies to coal, gas and oil....

Hi Alan,

I think the figure of 19V and about 4.74A (19 x 4.74 totals just under 100W power) is the maximum a charger would be drawing; you might well find that the average power a laptop needs is rather less than that. Though just how much depends on many factors! Presumably the laptops aren't actually being actively used for 18 hours a day - much of the time they will be idle, so if you change the power settings to switch off the screen and power down the hard drive, or go into standby while they are not being used, the consumption will go down dramatically. You could get one of those little electricity meters from Maplin if you wanted to measure their actual consumption.

I do have one customer who has set up a solar powered webserver using a laptop - I think he reckoned on nearer 30W rather than 100W. See the gallery page or his web page.

Having said that, you are right that you would still need a large array if you want to be able to power the system all through the winter with solar panels alone. The fact is that you get very much less power in winter than summer with solar, so to size the system such that you get enough even in the depths of winter means that you do need a big system. I reckon on solar panels rated at 20x the average power consumption. So if you have a 30W load on for 18 hours a day, thats 75% of the time, so an average of 22.5W - to power that fully in winter would need approximately 450W of solar panels. In summer you would get away with not much more than 100W of solar panels per laptop.

Hope that helps! All the best,

Andy

Powering everything under the sun!

2008-07-15T09:28:00.001+01:00

Hi. I am having a narrowboat built and would like some information on solar panels. I have set aside an area approx 6ft long on the roof and between 3 and 4 feet wide (chimney). I wish to run a TV/fridge/laptop/printer/ lights/12v w/machine/ induction hob (2 ring)/ combi microwave. Heating will be by a solid fuel with capability to bake potatoes etc and by diesel c/h. I would also like to be able to heat water with the electrics on days that I do not move. How many solar panels would I need and how big could my battery bank be? I may also need a little solar panel for the envirolet loo.

Thanks, Kath

Hi Kath,

Some of those appliances use a huge amount of power. Whilst it is relatively easy to power energy efficient lights and a radio by solar power - they typically only consume tens of watts - it's a completely different ball game trying to power an induction hob, which will consume thousands of watts when it's on! Laptop and TV are somewhere in between - definately possible by solar, but it won't be a small array.

I do know one narrowboat owner who cooks by electricity. He has 8 180W solar panels that take up most of his roof, and an enormous wind turbine - and he still has to run a generator every day if he wants to boil his kettle.

On a 6' x 4' section of roof you could fit a maximum of 3 Kyocera 130W panels - so a total of 390W of power. I suggest you play with our solar panel calculator to see roughly what appliances you can expect to be able to run from 390W of solar panels. They will certainly make an enormous difference - but you shouldn't expect to be able to run anything that requires heat on a regular basis from a solar array of that size.

The Envirolet can be wired into the rest of your 12V system; there is little point in having a seperate battery and solar panel for it. But even they are quite energy hungry. Envirolet recommend a 50W solar panel to provide sufficient power.

hope that helps - and sorry not to be more positive! regards, Andy - Midsummer Energy

Multiple regulators on one battery bank

2008-06-18T12:28:00.001+01:00

Hello. I have 2 sets of solar panels (200W each) with their own regulator, and a wind generator with its own regulator. However they are not all charging efficiently. Even though the battery bank is fla,t when it is sunny and windy the wind regulator slows the wind gen down and one solar reg beats the other down. So I am getting maximum recharging from only one source not all 3. I think the regulators are sensing the charging voltage of the dominant regulator and thinking the battery is fully charged. Any suggestions? I have been looking for a regulator to manage 3 inputs (and 2 outputs would be good) but can't see any. Could I wire all 3 regulators to a 4th regulator for the bank? Thanks. Stephen.

Hi Stephen. You are right that whenever you are charging a battery, the voltage will increase, and therefore any other charging sources attached to the battery will see a higher voltage and think the batteries are slightly more highly charged than they actually are. That's pretty much unavoidable.

The effect should not be very large, however, and it's not necessarily a bad thing, as it prevents overcharging. PV arrays trickle charge batteries, and with a healthy battery bank and decent sized cables between the battery and regulators, you shouldn't see a massive voltage increase. If you are - if they are cutting out even when you think the batteries are flat - it's suggesting the voltage is rising above 14.4V (the usual cut off), even with a relatively low charging current. That suggests to me that the batteries are on the way out.

Regulators are designed to be used in parallel in the way you have them wired, so I very much doubt you will find any difference if you do change the regulators. Trying new batteries is in my opinion far more likely to give you good results.

Hope that helps.

Lizard heating by solar power - is it practical?

2008-06-05T08:38:00.001+01:00

Hi - I was wondering if you could help me, I'm looking to buy solar panels for my garden shed but don't know what one would be suitable. In the shed I have a glass tank with a lizard in it and I would need the panel to power an 80w fluorescent tube that is on 12 hours a day and a 190w ceremic heater bulb which is on 24 hours a day. Can you help? Cheers Andrew

Hi Andrew,

You can use the solar panel calculator to work out how big a solar panel array you would need. But I can tell you now that running a heater all the time would require a huge array unfortunately - 190W is a very big load to be powering for 24 hours a day. In fact I usually reckon that in the depths of winter you need a solar array with a rating of 20 times the average power draw of the equipment you want to power, as on cloudy days you don't get a big return from the panels. So, for a 190W continuous load, you would need about 3800W of solar panels - which would cost over £10000 and wouldn't fit on your shed roof anyway. Sorry!

If the ceramic heater is on a thermostat and is only actually on 10% of the time, that would make a huge difference - it would drop the array size to only 380W, which might just be practical.

Expensive lizard. Even on mains electricity you are burning about 5.5 kWh per day with that light on 12 hours a day and heater on continuously; at 13p per kWh that works out at over £250 per year.

Solar panels on garden shed

2008-05-15T16:12:00.001+01:00

I know nothing about how to set up a solar panel system. I am wanting to get power to a garden workshop to run a light, and power a plug socket for using small electrical equipment eg. soldering iron, drill. What products would you suggest would be suitable and how would I set them up?

Hi Jennifer,

A solar panel system is extremely simple - a solar panel charges a 12 volt battery (usually through a regulator, a little circuit that prevents the panel overcharging the battery), and then you can power your appliances off the battery. Many appliances are designed to run directly off 12 volts - anything that plugs in a car cigarette lighter socket for example - but you can also use an inverter to convert the 12V from the battery into 240V to power standard household appliances.

In your case you would need:
1) a solar panel kit (which includes the regulator and wiring) such as our 40W kyocera solar panel kit.
2) standard 'leisure' battery, available from any motoring store
3) a 12V light to run directly from the battery (eg the Labcraft Trilite),
4) an inverter such as the 500W model, in order to run 240V appliances such as power tools. For bigger tools you might need a bigger inverter - the 1000W model would be more than adequate for most household power tools.

The 40W solar panel kit should be adequate for occasional domestic use in a shed. If you were using the system for more than an hour or so a day on average you might need a bigger panel.

Do hope that helps. I know quite a number of people who have done similar things on their garden shed - it is pretty easy to set such a system up.

Is an 80W panel sufficient for a motorhome?

2008-05-12T08:16:00.001+01:00

Have just bought a motorhome and want solar panels suitable for long term living in van. Would your 80w panel be sufficient, and what other items would I need ready for fitting this panel on my van?
Thanks - Andrea

Hi Andrea,

Whether 80W is sufficient depends entirely on what appliances you want to power! In the summer, for a few lights / water pump / radio etc it would be more than adequate; in the winter it might not be enough, especially if you also want to run things like a TV, laptop, or fridge.

Try our solar calculator to get an idea of what appliances you might be able to power.

If you buy the 85W solar panel kit it includes the regulator and all the wiring you need for fitting the panel. The only other thing you will need is some means of mounting it on the roof - it shouldn't be too hard to make up some suitable mounting brackets.

Solar for heat gun and lighting

2008-05-08T09:28:00.001+01:00

Hi - I am going to start a business car window tinting in a standard basic garage; however I have no means of electric so I wonder if you have a solution. I need enough energy to power a normal light supply and also to be able to power a heat gun for 2-3 hours (not constant) a day. I do not have lots of money so would be looking for the cheapest solution. Thank you - Kieran

Hi Kieran,

It's possible - but it might not be all that cheap!

You can use our Solar panel calculator to work out how big a system you need. For example, a 40W light for 4 hours and a 1000W heat gun for 30mins per day would need about 516 watt-hours of electricity each day. 200 watts of solar panels would give you that much for most of the year, but probably still not enough in winter.

Some idea of the costs:

200W solar panels - about £800
regulator - £95
batteries - about £150
inverter - £148.

So it does add up!

regards, Andy

Running 240V appliances by solar power

2008-05-08T09:07:00.001+01:00

I would like to build a device where a solar panel is connected to a UK standard plug socket, to power UK standard (240 volts I think) electrical appliances. As far as I am aware I need a solar panel, a diode, a regulator, a battery, an inverter, and a plug socket. The unit would be stand-alone, not connected to the national grid, but able to power standard 240v electrical appliances, e.g. electric kettles.

My questions are these. Is this project possible (I assume it is, beacause it can be done on a larger scale by linking solar panels into the house mains electricity)? How do I calculate the energy input output requirments of the components (can I use any components of different energy flow allowances with each other)? Do the components have to be conected in a special way?

Thank you, Chris

Hi Chris,

Yes, the project you describe is certainly feasible, and in fact it's quite common to use solar power in this way to power 240V appliances where you don't have a national grid connection.

You can use our solar panel calculator to work out how much power your appliances will take, and how big a solar panel array would be needed to power them. The inverter size you need depends on the maximum power you need to draw from the system - so a laptop charger would be fine with a inverter of a couple of hundred watts; a kettle however would need a 2kW inverter at least.

You don't need a diode in the system if you have a regulator - the regulator stops the panel discharging at night.

regards,
Andy
Midsummer Energy