Hello,
First at all hello to everybody ! I am new here and new in PV. Writing from Belgium. I need some advises !
First at all, the objective:
I have no solar panels, a heat pump (air-water), and a 300L water tank heated by the heat pump and by a 3kW resistance to make the bridge when heat pump is not enough.
This additional heating element is 240V AC and managed by the heat pump motherboard, with just an on/off relay.
This tank is my main electricity consumer. Weather is quite cold in Belgium but the isolation is good. Also regulation makes PV installation expensive if I plug it on the network. Prosumer taxes are going higher, and not suitable for a very small installation. So I have to stay off-grid.
My idea would be to inject some PV power in this boiler and only this. I expect the boiler capacity to be higher than panels. I do not need any battery storage, tie-grid, ... I cannot change the AC heating element. I cannot add a second element. So I will plug my system on it, and share it with the heat pump controller.
My current understanding:
- I would need 2x 300W panels, a MPPT charger, a 12V or 24v battery, a 1000W inverter
- Since I will never reach 3kW, my idea is to use a SSR to limit current in the heating element and bring it down to 500W (or another power to chose). With some Arduino, and electronic, I will manage to disconnect my injection when the heat pump power on the 3kW circuit. When this circuit is off, my regulated circuit would be on.
Now I have lots of questions/doubts:
- I need battery with this setup for the MPPT but in fact I do not need battery storage. Is there a more efficient way without battery ? Maybe without MPPT but I have doubt since the solar panel management with variable impedance seems needed to me.
- If I cannot make it without battery, I feel I can just take 2x 12V AGM battery plugged in series. Since I do not need storage, they can be quite small, just be sure it can deliver the injected power in the heater. As soon as it discharge, my Arduino would cut off the load. Or maybe MPPT can be setup to not really use the battery ?
- I could play with DC current into the AC heating element, but I am not very confortable with this.
- I think I will try to put the SRR at test and check how much heating I get with 500W power for testing before buying solar system
- About rentability, if I inject all 2 panels power in the heating tank, I guess it should be ok, loss would be limited. Should be paid in < 4 years (guts feeling).
So this is a first description of my DIY project with PV. I am very motivated . Please ask anything and share your thoughts. I did not find similar project on forums (no battery storage, AC heating element, no usage outside of sunny period, water heating only, off-grid).
First at all hello to everybody ! I am new here and new in PV. Writing from Belgium. I need some advises !
First at all, the objective:
I have no solar panels, a heat pump (air-water), and a 300L water tank heated by the heat pump and by a 3kW resistance to make the bridge when heat pump is not enough.
This additional heating element is 240V AC and managed by the heat pump motherboard, with just an on/off relay.
This tank is my main electricity consumer. Weather is quite cold in Belgium but the isolation is good. Also regulation makes PV installation expensive if I plug it on the network. Prosumer taxes are going higher, and not suitable for a very small installation. So I have to stay off-grid.
My idea would be to inject some PV power in this boiler and only this. I expect the boiler capacity to be higher than panels. I do not need any battery storage, tie-grid, ... I cannot change the AC heating element. I cannot add a second element. So I will plug my system on it, and share it with the heat pump controller.
My current understanding:
- I would need 2x 300W panels, a MPPT charger, a 12V or 24v battery, a 1000W inverter
- Since I will never reach 3kW, my idea is to use a SSR to limit current in the heating element and bring it down to 500W (or another power to chose). With some Arduino, and electronic, I will manage to disconnect my injection when the heat pump power on the 3kW circuit. When this circuit is off, my regulated circuit would be on.
Now I have lots of questions/doubts:
- I need battery with this setup for the MPPT but in fact I do not need battery storage. Is there a more efficient way without battery ? Maybe without MPPT but I have doubt since the solar panel management with variable impedance seems needed to me.
- If I cannot make it without battery, I feel I can just take 2x 12V AGM battery plugged in series. Since I do not need storage, they can be quite small, just be sure it can deliver the injected power in the heater. As soon as it discharge, my Arduino would cut off the load. Or maybe MPPT can be setup to not really use the battery ?
- I could play with DC current into the AC heating element, but I am not very confortable with this.
- I think I will try to put the SRR at test and check how much heating I get with 500W power for testing before buying solar system
- About rentability, if I inject all 2 panels power in the heating tank, I guess it should be ok, loss would be limited. Should be paid in < 4 years (guts feeling).
So this is a first description of my DIY project with PV. I am very motivated . Please ask anything and share your thoughts. I did not find similar project on forums (no battery storage, AC heating element, no usage outside of sunny period, water heating only, off-grid).