We probably watch about 5 hours Sky Tv a day using a 19" LCD flatscreen and a Sky digibox. In order to recharge a 110am battery, what size of solar panels will be required? And before any one makes any snide remarks or comments about watching TV in the caravan, I don't have much choice!
Solar panels and re-charging
- Thread starter Surfer
- Start date
Hello Surfer,
Normally most caravanner's who have made solar power work for them find the need between 48 and 60W panels to keep their batteries well charged, BUT that is usually for lighting, heating fan and and pump without much TV usage.
In your case you have the set on for about 5Hours per day, which is more than usual. so a bigger solar panel would be needed.
The size of panel you will need will largely depend on how much power the Sky box and TV actually use.
Each appliance should have a data plate that will tell how many watts each consumes. Add then together for the instantaneous power of the set up uses.
Now it may seem simple, just get a solar panel to match the wattage of television and Sky box, but unfortunately its a little more complicated than that.
You need to know the total amount of energy the set uses whist it is on, so multiply the instantaneous wattage by the number of hours to get the Watt-hours.
So for example if your TV and Sky box have a combined wattage of 30W (just a guess) then over 5 hours you will use 30x5 = 150WH of power. That is how much power we need to be able to restore to the battery just for the TV and Sky box.
Unfortunately batteries are not 100% efficient at giving back the power used to charge them, At a rough estimate the are only about 50% efficient, so to store the equivalent of 150WH we need to have roughly 300WH of charging power.
Given that solar panels only work in daylight, and that the daylight varies in intensity throughout the day changes in length depending on the time of year, on average you can only assume about 8 hours of charging time so to replenish 300WH we need panels rated at 300W/8H = 37.5W. Don't forget that this is just for the TV and sky box, so using other caravanner's experience of a base load of 48w ad your additional load of 37.5 gives a panel rating in the region of 80 to 100W.
Obviously if your TV and set box have power rating different to my assumptions than you will need to recalculate to find the likely sizeof panel you will need.
Normally most caravanner's who have made solar power work for them find the need between 48 and 60W panels to keep their batteries well charged, BUT that is usually for lighting, heating fan and and pump without much TV usage.
In your case you have the set on for about 5Hours per day, which is more than usual. so a bigger solar panel would be needed.
The size of panel you will need will largely depend on how much power the Sky box and TV actually use.
Each appliance should have a data plate that will tell how many watts each consumes. Add then together for the instantaneous power of the set up uses.
Now it may seem simple, just get a solar panel to match the wattage of television and Sky box, but unfortunately its a little more complicated than that.
You need to know the total amount of energy the set uses whist it is on, so multiply the instantaneous wattage by the number of hours to get the Watt-hours.
So for example if your TV and Sky box have a combined wattage of 30W (just a guess) then over 5 hours you will use 30x5 = 150WH of power. That is how much power we need to be able to restore to the battery just for the TV and Sky box.
Unfortunately batteries are not 100% efficient at giving back the power used to charge them, At a rough estimate the are only about 50% efficient, so to store the equivalent of 150WH we need to have roughly 300WH of charging power.
Given that solar panels only work in daylight, and that the daylight varies in intensity throughout the day changes in length depending on the time of year, on average you can only assume about 8 hours of charging time so to replenish 300WH we need panels rated at 300W/8H = 37.5W. Don't forget that this is just for the TV and sky box, so using other caravanner's experience of a base load of 48w ad your additional load of 37.5 gives a panel rating in the region of 80 to 100W.
Obviously if your TV and set box have power rating different to my assumptions than you will need to recalculate to find the likely sizeof panel you will need.
You don't say if you will be powering the TV and sky box via an inverter but they are very inefficient and I would guess that you need to factor in something like 20% for loss of efficiency in the inverter depending on the model. From memory the usual sizing guide for photovoltaic panels is to x3.5 the panel output and that will be the average daily output in watt /hours in the summer months. In the winter the average is x1.
You are going to need some pretty big panels to keep your TV going. You also need to take into consideration that there will be many days of low light levels and you will need ample reserve battery capacity to allow for these times. An additional 110A/h battery would probably be a good move.
The above is going to make for an expensive viewing cost per hour!. It is often cheaper in the long run to look at reducing the demand for power by using low energy devices such as the new LED/LCD tv's that work directly off 12v and are available in smaller sizes that use much less power. As an example the Kogan 22" uses less than 60W and there have been reports of it using about 20W once in use. I don't know about the power demands of a Sky box as I have a dislike of anything to do with Murdochs empire.
You are going to need some pretty big panels to keep your TV going. You also need to take into consideration that there will be many days of low light levels and you will need ample reserve battery capacity to allow for these times. An additional 110A/h battery would probably be a good move.
The above is going to make for an expensive viewing cost per hour!. It is often cheaper in the long run to look at reducing the demand for power by using low energy devices such as the new LED/LCD tv's that work directly off 12v and are available in smaller sizes that use much less power. As an example the Kogan 22" uses less than 60W and there have been reports of it using about 20W once in use. I don't know about the power demands of a Sky box as I have a dislike of anything to do with Murdochs empire.
.....my Sky box uses 40watts and my 14"TV uses 35watts and my inverter is 90% efficient.
Thus my set up uses about 84watts.
Cannot help with solar panels as I rely on the tow car to charge the batteries.
Thus my set up uses about 84watts.
Cannot help with solar panels as I rely on the tow car to charge the batteries.
hello, we have an extra 110 battery just for our tv, we charge it with 2 solar panels linked together giving 70 watts. charges up both batteries plus tv, lights etc. we dont use the water pump though, plastic water containers to save on battery use. We watch about 5 hrs each evening so no problem with that.
For that you will need a lot of panel and they are expensive- if they're cheap they won't work so well. A cheaper option is to have a separate battery for the telly. Get a charger set up in the boot and when you run round in the day recharge the battery. I use tv and satellite. Anyone who offers criticism only caravans in the good weather- it's a long night without in the winter when it is dark at 4! You enjoy it.
Seems the cheaper option is not to rally on fields without any electric. Parksy had almost persuaded me, but it seems a no go. It would take years to recoup the cost of the solar panels weighed up against the savings made by using non EHU sites.
We do have a 300w invertor but have never used it although we have had it 6 years! The last tiem we stayed on a non EHU site we went to the pub, had a meal and few drinks, so in essence the EHU site was cheaper! LoL
We do have a 300w invertor but have never used it although we have had it 6 years! The last tiem we stayed on a non EHU site we went to the pub, had a meal and few drinks, so in essence the EHU site was cheaper! LoL
Hi, We use a 40 watt panel connected to 2x100ah leisure batterys connected together for rallies, they run a 12v lcd tv and a 12 volt sky box which was purchased off ebay, on a full charge we get around 8 hours tv and sky usage. On a sunny day, the leisure batteries can be fully recharged ready for use in the evening. They are heavy to lift in and out of the car though, but do the job even for a full week of rally camping.
Parksy
Moderator
Hi SurferSurfer said:
I deliberately refrained from offering advice within this topic until you had received some balanced replies because I didn't want to unduly influence you (I know that I can be persuasive sometimes
We've met caravanners who react with shock and horror when we mention watching tv but we're not into cards or board games when it rains. We already read quite a lot and we regard our caravan as a sort of mobile hotel room in which we take full advantage of every comfort on offer including the choice of watching tv whenever we want to. You don't need to justify yourself to anybody and if the truth were known more caravanners watch tv than would care to admit it
From a purely financial sense a 100 watt solar panel with an efficient voltage regulator is an expensive investment simply as an occasional replacement for ehu.
Anecdotally speaking, what we've found is that an 80 or a 100 watt panel with a good 110 amp/hour leisure battery would work fine during the lighter months. From October until mid March a solar power source would struggle to provide enough power to keep the leisure battery fully charged enough for 5 hours of tv viewing using an inverter although the 12v lighting, water pump and radio/ i-pod would still work fine off ehu. (we replaced our halogen and 'normal' 12v bulbs with led's which give as much light for less power consumption)
A decent solar panel of 100 watts can be bought for between £170-£220, they are guaranteed to provide 80% of their output for 21 years so barring accidents our panel represents a long term investment but whether a similar investment is worth your while depends on several factors.
In our case what we also bought into was the freedom to go where there is no 240v supply available such as music festivals, the grounds of stately homes and yes, even selected farms if the surrounding countryside is worth the trip. We sometimes stay off ehu for a week during the summer, of course during the darker colder months we use ehu's like everybody else.
What you would have to weigh up is how often you would be likely to use a solar panel, you certainly wouldn't need one just to try a couple of weekend rallies so as to use your caravan a bit more for not too much money especially if your towing vehicle has a 12s socket which could maintain the level of battery charge battery charge if necessary.
Hello ij,
I think you may not have expressed yourself very well. according to your posting, your 200Ah of battery only gives you 8 hours of TV. If that were true and after 8 hours your batteries were flat, then that would be a power consumption of 2.4kWh! or you tv is using 300W an hour!
What makes me suspect that is not what you mean, is your comments about being able to "Fully Recharge" the batetries with a 40W solar panel.
In the UK due to our latitude on the face of the earth we dont our longest day (june 21st) we only get about 18 hours of daylight, and due to the rotation of the earth a fixed solar pane will give on avafer only about 60% of it rated output. so your 40W panel will on average only give about 24W (2A at 12V) so even on the longest day the total power you are likely to see is 432W or 36Ah.
also given tha batteries are only about 50% effieicent at retaining the actual charge current they see means that only about 218W can be stored. So if that full recharges your batteries then you are using far less power than you state, and infact you dont need to carry two batteries.
Even if my down rating of available light and battery charge retentoin is too pesimitic your still well within the the single battery teritroy.
I think you may not have expressed yourself very well. according to your posting, your 200Ah of battery only gives you 8 hours of TV. If that were true and after 8 hours your batteries were flat, then that would be a power consumption of 2.4kWh! or you tv is using 300W an hour!
What makes me suspect that is not what you mean, is your comments about being able to "Fully Recharge" the batetries with a 40W solar panel.
In the UK due to our latitude on the face of the earth we dont our longest day (june 21st) we only get about 18 hours of daylight, and due to the rotation of the earth a fixed solar pane will give on avafer only about 60% of it rated output. so your 40W panel will on average only give about 24W (2A at 12V) so even on the longest day the total power you are likely to see is 432W or 36Ah.
also given tha batteries are only about 50% effieicent at retaining the actual charge current they see means that only about 218W can be stored. So if that full recharges your batteries then you are using far less power than you state, and infact you dont need to carry two batteries.
Even if my down rating of available light and battery charge retentoin is too pesimitic your still well within the the single battery teritroy.
Hi, I find my leisure batteries lose the power to run the tv and sky box after approx 8 hours, but it still has power to run other items in the van, I am probably being over cautious with the 2 leisure batteries, but we do like the tv at an evening, especially my 7 year old daughter.
I am staying on a lovely site at the moment at Ashton underhill near Evesham , handy for the Cotswolds , Stratford upon Avon , super wide pitches , and its the most peaceful site i have stayed on , nice showers and WC , and at £7.00 per night including electric who needs a rally field or a solar panel
joeby said:
The Star Inn just down the road used to do a nice curry plus a beer ofr a fiver a head. Nice site. Used to be a CC CL site previously.
Unfortunately winter caravanning is totally out of the question for us as we both suffer very badly in the winter months from about Mid Nov until about mid March due to the cold. during the warmer months we normally go away for at least 3 days at a time to make it worth while with petrol costs.Parksy - Moderator said:
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