PV questions for Newbuilt

yannakis

I've purchased a house with PV "out of the box", and I've seen them produce up to 6.2kWh on very bright days. We haven't moved in yet, but the plan is to kind of line up the big appliances with timers (washer/dryer/dishwasher) to run during the day.

There is no installation to manage the excess electricity (i.e. redirect it towards an immersion), so it will probably just be fed back to the grid for free. Do you think it would make sense to install a battery of some sort and store the excess electricity in order to use it later, when we're back from work?

unkel

No it will not make any financial sense to install either a battery or a system that can divert your excess electricity to your immersion (heating your hot water)

The latter is not expensive to get installed though, around €500. But the savings are very low, with the standard part L size PV install maybe €10-€20 per year

"Free" solutions like your plan to use up as much of your production by staggering appliances while the sun shines do make sense, so go for it!

yannakis

Thanks @unkel!

rolion

We will not have FIT for home owners unless "you" have the capability of generating AND storing a huge brown panel..
Get a PV to hot water diverter, it will warm up the "Delta T" of your cylinder and pays back shortly...rather than giving for fre to Mr Grid .

Enjoy your panels and welcome aboard !!


Backing up with facts that a diverter makes more sense than scheduling applciances:

My Diverter figures today,on a bad day i will say:



My generation today,as well,on a bad day ,but completely unpredicatbel for the wash machine:




the MOST important factor that few people understand AND capable of explaining is the amount of energy (any) needed to heat up from 10ish to 20 ish and to 50ish ! A diverter will save you money by pre-heating the botttom of the cylinder. Not lastly,the convenience of having FR€€ hot water (in good days)...paid in advance !

freddyuk

The more you can store on site the more you will save providing it is installed with effective insulation so investing in a decent properly sized cylinder is also key. By having a triple coil (thermal) or twin top and bottom immersions (PV)  you can top load the cylinder thus heating the top portion first where useable hot water is drawn off. When the top is hot the system can then automatically divert to the bottom. Normally the solar is fed to the bottom all the time so the available energy has to heat the whole cylinder before it gets hot enough to use. This does raise the incoming water temperature thus saving the boiler load as said but by heating the bit you actually need quicker makes any system more effective. Mechanical diverter valves avoid the need for powered valves in thermal systems.
Most decent immersion diverter units have 2 channels so you can divert to 2 loads using the free solar proportionally so cylinder and heated towel rail for example which only uses free incoming solar. After that you can switch loads directly via wireless power socket outlets (extra cost kit) to mop up any spare capacity. Having an American hot fill washing machine means bigger savings and now there are dishwashers that take hot water fill so these too become acceptable in a low energy house (well if you are told it is not negotiable it is the best option to help recoup the cost!).:'(
Only having a minimal amount of PV on the roof (Part L) will mean much longer pay back and 6kWh per day is not going to leave you any spare to divert unless your base loads are near zero.