Solar Panels and Setup Needed to Power Bungalow with no Direct Grid Power Ask questions and find answers to many subjects relating to electrics and electrical work

[greengrass]

For a say a 3 bed bungalow out in the ' back of beyond' no mains power what type of Solar panels or extra equipment would be needed to run lights heating washing machine dishwasher TV

I say a battery for storing power as the panels only gather power during daylight hours and if facing south are more beneficial. 'Er indoors' says I'm talking rubbish panels will work on their own I've seen it on tv. I even explained that if you are connected to the national grid and there is a power cut you will not get power unless you have back up batteries.

Hopefully the responses will prevent a possible divorce.
Many thanks for responses.

[thedoctor]

Hi

Although not in any way an expert, I have been doing some personal research in this area on and off over the past few months on a smaller scale than powering a house and if you want to run your home off of solar that has no direct connection to the grid then you would need battery storage for sure.

Again, not 100% sure but with the commercially installed panels, they do power your home and any excess that is generated is then fed back into the grid where you then receive a payment (feed in tariff).

The amount of power that is generated also varies greatly depending on the direction that the panels are facing e.g. north, south, east, west etc…. whether there is lots of cloud cover, whether they are shaded, whether they are in direct sunlight for long periods of the day etc….

As a very rough estimate, to power the whole house, you would need a setup that would generate somewhere in the region of a 4 kilowatt hours (4kWh) as this should produce enough to power any appliances etc…. but again, it very much depends on position of panels and also where it would be in the country (this is based on a southern UK location).

A friend of mine has just done this to a property they have converted in the south of Spain that has no direct power from the grid. They have a 4kWh system supplying batteries that then powers the house that gives them around a 900ah supply enough to run a large American style fridge, washing machine, lights, TV, laptops, phone chargers, mig welder, power tools and other appliances, but this is in the south of Spain with direct sunlight for 95% of the year.

The system itself comprises of 4KW worth of panels, 4K inverter, 4 or 6 (not sure how many) 6V deep cycle batteries (must be deep cycle) and required cabling. Again, not sure how batteries are setup in terms of series or parallel, but tis is the basic setup.

There are now quite a few independent solar “specialists” dotted around the country that can offer advice on the size/type of setup that would be needed so it’s definitely worth contacting one of these guys for a more expert opinion.

There is also a wealth of info online about such systems. As quick Google search for “off grid living” or “off grid solar setup” will give quite a bit of info.

Hope this helps

[katoosh525]

You need to really check out the massive amount of batteries required here. If you live in Spain, and get sunlight every day, then you can reckon on the batteries having to run your home for 10 hours in summer, 14 in winter. In the UK you may have to go for days without much energy coming in from those panels. Reckoning on a 1KW draw overnight, for your fridge and a telly and heating system etc, that is a 12,000 watt hour requirement for a 12 hour period.
That is 1000AH from 12v batteries at 100% efficiency.
If you are going to do this, I would really also advise having a backup diesel generator, ideally an inverter, and some control circuitry to automatically turn it on before your fridge turns itself off.

[thedoctor]

@katoosh525 - you’re right there, as said, I’m not an expert in the subject by any means and have only been looking at smaller setups that do not require constant draw, but those are some very good points and the required deep cycle batteries are not cheap in the slightest.

As said, if you are considering this then you do need to speak to someone with experience of off grid solar setups in the UK as they will have a much better idea of system size and requirements

[greengrass]

Thank you for saving my marriage 'Er indoors has to accept defeat and that storage batteries and back up generator would be required because lately 90% Sun missing in uk it's thoughts of investment in three families investment derelict terraces of three holiday croft cottages Scotland.

[ericmark]

Try a narrow boat forum, using solar panels is common with narrow boats also wind chargers. Not cheap, and a lot to consider. I worked on some houses in the Falklands when I was there some 30 years ago now and tried to install a system to keep lights and freezer going. At that time inverters were far more expensive than today.

But what the farmer did was buy an old bus, sold engine, used body as a green house, used the Ni-iron batteries and interior lamps in his house.

Batteries are the big issue Ni-iron do not mind being left flat so batteries from a milk tanker or bus both can use Ni-iron even second hand would be a good start.

If you ask the narrow boat owners they will tell you batteries last about two years. Main reason for low life is not being fully recharged. Ask a milk float owner and they look at 7 years same with fork lift they are better looked after and also you can change one cell at a time.

Even with wind chargers and solar panels to ensure batteries are charged fully at least once a week means a generator of some type.

This is not as bad as it seems. cooling water for generator can heat the house. On the Falklands the generator was the main tool and the solar panels and wind chargers were really only for when they were not at home. Even known as windy islands it was found a electric fence with a 5 amp solar panel was more reliable than a 15 amp wind charger. The only time solar panels failed was in the snow.

Batteries and panels for lights, TV and other gear you would find in a caravan is OK. But for washing machine you really do need a generator. Sons narrow boat we tried using 12 volt inverters. It was a failure you need at least 24 volt, 48 volt would be better for large (3kVA) inverters which means at least 4 x 160 Ah batteries. Also only inverter washing machines would work off an inverter because of the start amps.

Inverter need to be true sine wave. Although much will run off a simulated sine wave the inverters giving out a simulated sine wave tend to be low quality. Sons gave out expensive blue smoke.

The solar panel needs a pulse width modulated controller which transform the input so the input voltage starts low climbs to mid day then drops again but output voltage is stable. These units squeeze more power out of the panels and are also used with wind chargers. Often one controller does both solar panels and wind charger.

Look at Rutford they seem to be market leaders. Also Sterling they also do special generator controls. But as I say talk to the narrow boat users they have got non grid-tie solar panels down to a fine art.

[greengrass]

[quote="ericmark"]Try a narrow boat forum, using solar panels is common with narrow boats also wind chargers. Not cheap, and a lot to consider. I worked on some houses in the Falklands when I was there some 30 years ago now and tried to install a system to keep lights and freezer going. At that time inverters were far more expensive than today.

But what the farmer did was buy an old bus, sold engine, used body as a green house, used the Ni-iron batteries and interior lamps in his house.

Batteries are the big issue Ni-iron do not mind being left flat so batteries from a milk tanker or bus both can use Ni-iron even second hand would be a good start.

If you ask the narrow boat owners they will tell you batteries last about two years. Main reason for low life is not being fully recharged. Ask a milk float owner and they look at 7 years same with fork lift they are better looked after and also you can change one cell at a time.

Even with wind chargers and solar panels to ensure batteries are charged fully at least once a week means a generator of some type.

This is not as bad as it seems. cooling water for generator can heat the house. On the Falklands the generator was the main tool and the solar panels and wind chargers were really only for when they were not at home. Even known as windy islands it was found a electric fence with a 5 amp solar panel was more reliable than a 15 amp wind charger. The only time solar panels failed was in the snow.

Batteries and panels for lights, TV and other gear you would find in a caravan is OK. But for washing machine you really do need a generator. Sons narrow boat we tried using 12 volt inverters. It was a failure you need at least 24 volt, 48 volt would be better for large (3kVA) inverters which means at least 4 x 160 Ah batteries. Also only inverter washing machines would work off an inverter because of the start amps.

Inverter need to be true sine wave. Although much will run off a simulated sine wave the inverters giving out a simulated sine wave tend to be low quality. Sons gave out expensive blue smoke.

The solar panel needs a pulse width modulated controller which transform the input so the input voltage starts low climbs to mid day then drops again but output voltage is stable. These units squeeze more power out of the panels and are also used with wind chargers. Often one controller does both solar panels and wind charger.

Look at Rutford they seem to be market leaders. Also Sterling they also do special generator controls. But as I say talk to the narrow boat users they have got non grid-tie solar panels down to a fine art.[/quote]


Many thanks ericmark very informative greengrass.

[greengrass]

Many thanks ericmark and all others.

Greengrass.

[Jimcub]

Does anyone have a shopping list of what's needed, perhaps where to buy and positive setups people use.

[ericmark]

Size matters. The use of a PWM regulator with output tracking will increase the power extracted from the solar panel. What the units do is early morning they use a low voltage and mid-day the voltage peaks returning to low voltage in the evening as this increases the watts extracted. Also the battery charging tend to use pulses and monitor the recovery voltage then major problem is to charge a battery being used at the same time as the items using the battery will alter the battery volts which are normally used to monitor battery state. So the device which connects solar panels to battery is quite complex.

The controllers need power to work so using a solar cell to keep a caravan battery topped up just not worth using the hi-tec charger a simple diode is enough with a zenor diode across the supply to stop over charging.

Also there are some specials which can grid tie and supplement the mains supply so a 6A shore line can provide a 16A supply when required using batteries and solar panels and even wind chargers all feeding the same system. Not cheap but they are made.

So the question has to be tailored around size and location there is no simple answer.

Also finding the products. I was given a link to the controller/inverter which did the grid tie with mains of small generator but when I tried to find it again I failed.

Many people think they can power their shed or garage with solar panels but in real terms the size of battery required to give power when required starts to get silly.

Also lead acid batteries are damaged if left part discharged for any length of time. So really looking at Nickel Iron or similar so it can be left discharged for an extended time.

Again it's a trade off. Use more solar cells than required and used lead acid or just on the limit and use Nickel Iron.

Pumping power into the national grid is easy, you can export all the power the solar panels produce but into batteries is another story.

Even into the nation grid is proving a problem. The power to a house has a voltage of 230 volt + 10% to - 6% so the solar panels must stop producing once the voltage hits 253 also should there be a power failure they must stop producing so it is assumed less than 216.2 volts is a power failure. Once they stop they must allow other solar panels to follow so they are locked out for a set time. This safety feature to stop when for example road works hit a cable the solar panels keeping the cable energised also means as the number of panels in an area increases so the times when they lock out also increases. Until the smart meters are fitted knowing when the panels are working is not so easy so home owners have be credited with power they did not really produce. Slowly this is stopping so many are now finding they are not getting the expected returns. Hire a roof schemes use their own installers and if they set their panel at 254 volts and yours is set to 253 volts then yours will always trip out first.

So grid tie is down to location. If the supply from the transformer spiders out just 1000 meters then volt drop is not a problem so the DNO don't need the 216.2 to 253 volt range so even with every house with panels there is no problem. But if the supply goes down one long street then the DNO may need the full 216.2 to 253 volt range between full load and no load at end of street so the solar panel works when street is using power but on the hot summers day when you expect max output it closes down due to over voltage.

Micro generation is a bit hit and miss.

[Jimcub]

Thanks for that in depth view.