Portable Power Stations

JKenH

I have made reference to my portable power station in other posts but as I believe these are very useful bits of kit for some people I thought a separate thread might be a good idea. 

In case any has not come across them a PPS consists of a an MPPT charge controller, a lithium battery and an inverter. Their primary use is for outdoor camping coupled with a portable solar panel but they have other uses,for instance providing power occasionally in an outbuilding such as a garage, summerhouse or home office where there is no mains supply. In the US it seems quite a few people use them for their off grid cabins. There are a wide range of battery sizes (from a couple of hundred Wh to over 3kWh and inverter outputs up to around 3kw. My PPS has a nominal capacity of 2.4kWh (just under 2kWh useable) and an output of 1kW (1.2kW) peak.

The first point I would like to make is that for most people a grid tied battery is a better option and the bigger the battery capacity you are after the better that option becomes. With some PPSs there is the option to add additional battery capacity but most smaller capacity ones are stand alone units so are not expandable. For some of us though a grid tied battery is not an option so a PPS gives us a cheap alternative to a professionally fully installed battery, albeit with much reduced functionality.

Some of the drawbacks:

Limited battery capacity unless you buy a more sophisticated model with expandable battery options and then it gets expensive. 

Limited charging rate - mine only charges at 210w from the grid or up to 500w from a solar panel so even on my GoFaster tariff I can only add 1kWh at cheap rate. It is though, a low enough charge rate to leave it on topping up during daylight hours.
Limited AC output potential. 

They cannot (generally) be connected to the house supply to cover overnight loads or supplement the grid supply when solar is low nor can they follow grid usage and only charge when there is spare PV.
There is some fan noise but you can put the PPS in another room and run an extension lead.

Why would one buy one? 

If you only have a limited need for a battery then they are a cheap option. You can currently get a nominal 2.4kWh capacity PPS for £1199 or £1119 (with a voucher code) which is cheaper than any installed battery option. Remember the PPS is not jus5 a battery, it includes the MPPT charge controller and inverter

They are portable so can be used inside or outside the house.

You can plug in a free standing solar panel directly to them if you want to generate your own (or some additional) PV.
They don’t need to be wired in to the house - you just plug appliances straight into the PPS. 
They have multiple DC outlets.
They provide a power cut back up. 

They have reasonable battery life. (Mine has a battery life of 2500 cycles, some have longer. I can’t see any means of measuring the number of cycles though.)

For me it was a combination of things. I wanted some form of power cut back up. (My electrician is going to put my boiler supply on a plug so I can have central heating when there is a power cut). I wanted to have the facility to time shift my PV generation for evening use and also have some limited option to charge on cheap rate electricity and use when rates are higher (my PPS is not ideal for this but others can charge faster). Finally I just wanted to play around with solar panels as I don’t have any south facing panels for winter. I have mounted a solar panel on a pallet with casters so I can follow the sun and use the battery to collect the generation. 

No, at around 50p per battery cycle (around 25p/kWh when my electricity costs me 13.3p) I am not expecting it to pay for itself, but I have satisfaction. I’ve just bought a second one for additional back up capacity.

Below is a link to a YouTube video from Anthony Dyer which finally convinced me that I should buy a PPS.
https://youtu.be/XEwhCDJp3os

QrizB

Thanks JKenH, that's a comprehensive account and a tidy little setup!

michaels

I read the title and thought this was gong to be a thread about a new SMR design from Rolls-Royce....

JKenH

QrizB said:

Thanks JKenH, that's a comprehensive account and a tidy little setup!

I was surprised how wide the sweet spot is for solar generation. Small adjustments to orientation and inclination don’t have anywhere near the impact I was expecting. (The PPS has a digital readout of generation so one can see the changes as you move it round/incline it.) I haven’t done any scientific measurements, just moved the panel a few degrees to try and optimise output as the sun goes round and climbs in the sky. To get really good output you only need to move the panel maybe 2 or 3 times during the day. The biggest problem with the panel being at ground level is avoiding shadows which will get worse in winter. 

michaels

JKenH said:

QrizB said:

Thanks JKenH, that's a comprehensive account and a tidy little setup!

I was surprised how wide the sweet spot is for solar generation. Small adjustments to orientation and inclination don’t have anywhere near the impact I was expecting. (The PPS has a digital readout of generation so one can see the changes as you move it round/incline it.) I haven’t done any scientific measurements, just moved the panel a few degrees to try and optimise output as the sun goes round and climbs in the sky. To get really good output you only need to move the panel maybe 2 or 3 times during the day. The biggest problem with the panel being at ground level is avoiding shadows which will get worse in winter. 

WE have W and S facing panels same inclination, in June their output is very similar, by December the S facing panels make much more.  Over the year as a whole the predominantly W facing array  does about 90% of what it would do if it was S facing.

Based on Octopus agile pricing the reduced W facing output is actually more valuable than higher S facing would be because it is available later into the afternoon when prices are higher.

JKenH

michaels said:

JKenH said:

QrizB said:

Thanks JKenH, that's a comprehensive account and a tidy little setup!

I was surprised how wide the sweet spot is for solar generation. Small adjustments to orientation and inclination don’t have anywhere near the impact I was expecting. (The PPS has a digital readout of generation so one can see the changes as you move it round/incline it.) I haven’t done any scientific measurements, just moved the panel a few degrees to try and optimise output as the sun goes round and climbs in the sky. To get really good output you only need to move the panel maybe 2 or 3 times during the day. The biggest problem with the panel being at ground level is avoiding shadows which will get worse in winter. 

WE have W and S facing panels same inclination, in June their output is very similar, by December the S facing panels make much more.  Over the year as a whole the predominantly W facing array  does about 90% of what it would do if it was S facing.

Based on Octopus agile pricing the reduced W facing output is actually more valuable than higher S facing would be because it is available later into the afternoon when prices are higher.

With my ENE and WSW roofs my PVGIS target is around 80% of a S facing roof but as you say the W roof generates a lot of power when you are most likely to need it. As my install was in the last year of FiT out right generation is not so important as useable generation. E and W roofs are, though, more prone to shading as they are doing much of their work when the sun is lower in the sky. In December the efficiency of my installation is only half what it would be if S facing.

From the experimenting I did in March 8 ‘O’s should be easily achievable (possibly more) on a good day if you can swing the panels round to meet the sun and there are no shading issues. Unfortunately we just haven’t had a fully sunny day recently to experiment further. There is no way though that I could get any useful generation before 6.30am unless I drag the panel 100 yds down the garden at 5am because of shading from neighbours trees. In the evening it is my own trees that cause a problem. You try to be green by planting trees and the good work comes back and bites you.

JKenH

My electrician came over today and fitted a plug and socket to my OFCH feed so in a power cut I can now have CH heating powered from my PPS. The CH was drawing just over 200watts so potentially I could run that for 9-10 hours from one of my Poweroak EB240 PPSs.

I also asked him if I could use the PPS to power the house from the grid by switching off the main isolator in the consumer unit (in mine it’s a big red switch) and he said that should be ok in theory but I would also need to isolate the solar pv installation or the panels would back feed into the PPS output and probably wreck it. (The chances are quite high that I would forget to do this.) Obviously I would have to be careful what load I placed on the system but it should be possible to have some LED lighting and low power items such as an LCD, the router etc running and the convenience of switching lights and appliances on and off around the house as required rather than having extension leads trailing everywhere.

That’s the theory, anyway, but I have not dared to try it yet. I am wondering if anyone with batteries and an emergency back up outlet has actually tried plugging the house in. 

michaels

JKenH said:

My electrician came over today and fitted a plug and socket to my OFCH feed so in a power cut I can now have CH heating powered from my PPS. The CH was drawing just over 200watts so potentially I could run that for 9-10 hours from one of my Poweroak EB240 PPSs.

I also asked him if I could use the PPS to power the house from the grid by switching off the main isolator in the consumer unit (in mine it’s a big red switch) and he said that should be ok in theory but I would also need to isolate the solar pv installation or the panels would back feed into the PPS output and probably wreck it. (The chances are quite high that I would forget to do this.) Obviously I would have to be careful what load I placed on the system but it should be possible to have some LED lighting and low power items such as an LCD, the router etc running and the convenience of switching lights and appliances on and off around the house as required rather than having extension leads trailing everywhere.

That’s the theory, anyway, but I have not dared to try it yet. I am wondering if anyone with batteries and an emergency back up outlet has actually tried plugging the house in. 

You didn't just wire on a 'suicide' plug that you simply throw the main isolator and plug into a socket onto the solar/battery output then

If power-cuts are looking likely this winter my plan is to stop the boiler supply being through a DP switch and instead putting it onto a plug so I can use the inverter output from my Nissan Leaf (unfortunately the V2G unit does not support Islanding).  We did have a power cut recently and used the inverter to run the internet wifi router as the majority consensus was that was the most essential load....

QrizB

JKenH said:

That’s the theory, anyway, but I have not dared to try it yet. I am wondering if anyone with batteries and an emergency back up outlet has actually tried plugging the house in. 

I think @Reed_Richards has, although his system is set to switch automatically?
You've also gained a mention over on the main "Energy" board:
https://forums.moneysavingexpert.com/discussion/comment/79249828/#Comment_79249828

1961Nick

JKenH said:

My electrician came over today and fitted a plug and socket to my OFCH feed so in a power cut I can now have CH heating powered from my PPS. The CH was drawing just over 200watts so potentially I could run that for 9-10 hours from one of my Poweroak EB240 PPSs.

I also asked him if I could use the PPS to power the house from the grid by switching off the main isolator in the consumer unit (in mine it’s a big red switch) and he said that should be ok in theory but I would also need to isolate the solar pv installation or the panels would back feed into the PPS output and probably wreck it. (The chances are quite high that I would forget to do this.) Obviously I would have to be careful what load I placed on the system but it should be possible to have some LED lighting and low power items such as an LCD, the router etc running and the convenience of switching lights and appliances on and off around the house as required rather than having extension leads trailing everywhere.

That’s the theory, anyway, but I have not dared to try it yet. I am wondering if anyone with batteries and an emergency back up outlet has actually tried plugging the house in. 

I have a 'Generator input plug' fitted to my supply with a changeover switch that breaks the grid connection & makes the connection to the generator plug. I can then plug it into the battery EPS, a petrol generator or I could use a PPS.

I would have liked to make it automatic with a changeover relay but the surge is so great that it trips the battery inverter unless I bring the circuits back one by one.

JKenH

1961Nick said:

JKenH said:

My electrician came over today and fitted a plug and socket to my OFCH feed so in a power cut I can now have CH heating powered from my PPS. The CH was drawing just over 200watts so potentially I could run that for 9-10 hours from one of my Poweroak EB240 PPSs.

I also asked him if I could use the PPS to power the house from the grid by switching off the main isolator in the consumer unit (in mine it’s a big red switch) and he said that should be ok in theory but I would also need to isolate the solar pv installation or the panels would back feed into the PPS output and probably wreck it. (The chances are quite high that I would forget to do this.) Obviously I would have to be careful what load I placed on the system but it should be possible to have some LED lighting and low power items such as an LCD, the router etc running and the convenience of switching lights and appliances on and off around the house as required rather than having extension leads trailing everywhere.

That’s the theory, anyway, but I have not dared to try it yet. I am wondering if anyone with batteries and an emergency back up outlet has actually tried plugging the house in. 

I have a 'Generator input plug' fitted to my supply with a changeover switch that breaks the grid connection & makes the connection to the generator plug. I can then plug it into the battery EPS, a petrol generator or I could use a PPS.

I would have liked to make it automatic with a changeover relay but the surge is so great that it trips the battery inverter unless I bring the circuits back one by one.

What happens to your solar generation when you switch to battery?