# Solar Upgrade Project, which panels and MPPT? **URL:** \ **Category:** DIY\ **Tags:** mppt\_controllers\ **Created:** [27 March 2026 15:13 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608 "2026-03-27T15:13:18Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![robovanbasten](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@robovanbasten](https://community.victronenergy.com/u/robovanbasten)\ **Post date:** [27 March 2026 15:13 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/1 "2026-03-27T15:13:18Z")
Hi all, after some advice from you knowledgeable lot if I may. I have solar on my main roof (16 x JA 385w), that is fed into my hybrid inverter. I also have a Victron MP2 8000VA with four PylonTech US5000’s. I’m thinking of adding some solar panels to the DC side of my MP2/PylonTech’s. I have spare ways in my 2nd Lynx Distributor. **Question 1** : I have space for 4 panels on the roof marked in red. Any recommendations on best panels to use? To maximise the space I’m thinking 4 panels in landscape orientation. However, I’m a bit limited on the width of the roof (its 3450mm). I was looking at the **REC Alpha Pure-RX** range as these are 1728mm (so two would _just_ fit), but their a bit pricey! I guess these are fairly premium panels and maybe a bit overkill for my situation? ![image](https://europe1.discourse-cdn.com/victron/original/3X/c/f/cf75ced9dd6c3e16f6b8cf262249fcbff5d63a10.jpeg) Question 2: Once I’ve decided on which panels, how best to determine which Victron 48V MPPT to use? I’ve been playing with the **MPPT sizing calculator** but its not super clear to me. I’m not sure if I need 4 panels in series on 1 string, or 2 panels in series on 2 strings? Any help much appreciated. Chris ---
**Author:** ![chrigu](https://avatars.discourse-cdn.com/v4/letter/c/ba9def/32.png) [@chrigu](https://community.victronenergy.com/u/chrigu)\ **Post date:** [27 March 2026 16:27 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/2 "2026-03-27T16:27:26Z")
I cant really help with choosing the panel type. Id use whatever fits the space and the budget, but i guess thats exactly the core issue of your first question. As for the MPPT, yes, as soon as youve defined the panel type you then use that to define the MPPT. In general, using a single series string is beneficial since the PV voltage will surpass the necessary threshold sooner in the morning to allow for early charging, and vice versa in the evening. However, the necessary 250/60 is much too big in terms of output current (a 250/30 would suffice, but doesnt exist), so using a 2S2P config on a 150/35 could be beneficial due to the price difference between the two. The bit of extra energy due to the 4S config on a 250/60 would propably take decades to break even compared to the almost half priced 150/35 ---
**Author:** ![lxonline](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/lxonline/32/25567_2.png) [@lxonline](https://community.victronenergy.com/u/lxonline)\ **Post date:** [27 March 2026 16:40 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/3 "2026-03-27T16:40:22Z")
> [@robovanbasten](#): > > its not super clear to me. I’m not sure if I need 4 panels in series on 1 string, or 2 panels in series on 2 strings? This will depend on panel (that you have chosen) VOC at min temps and the charge controller voltage chosen (150 or 250). But the basic maths is as follows. And the X50/YY where the YY is total wattage ÷ 48V. eg. (375w x 4)÷48 = 31.25A . Nearest is X50/35. The [150/35](https://www.victronenergy.com/media/pg/Manual_SmartSolar_MPPT_150-35__150-45/en/technical-specifications.html#UUID-1ff4776c-fdc6-3fdf-1e44-e6932221e259), which will probably mean the panels are 2S2P connected unless the isc is above the max short circuit of the mppt which is 35A. ---
**Author:** ![robovanbasten](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@robovanbasten](https://community.victronenergy.com/u/robovanbasten)\ **Post date:** [27 March 2026 19:58 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/4 "2026-03-27T19:58:50Z")
Thanks for your replies. So these are the panels I’m looking at –\> [Solareon - REC 460W Alpha Pure-RX Single Glass Bifacial All Black Solar Panel](https://solareon.co.uk/products/rec-460w-alpha-pure-rx-series-all-black?%5C_pos=2&%5C_fid=7572b20cc&%5C_ss=c) (460w x 4)÷48 = 38.33A. I’m assuming I could then use a [150/45](https://www.victronenergy.com/solar-charge-controllers/smartsolar-150-35), 2S2P connected? [[like this person has done](https://community.victronenergy.com/t/sizing-mppt-solar-contoller-for-4-550w-solar-panels/44435/7)] If I use the **MPPT sizing calculator** , it’s says I need a **[SmartSolar MPPT 150/70 Tr VE.Can](https://www.victronenergy.com/solar-charge-controllers/smartsolar-mppt-ve.can)** ![image](https://europe1.discourse-cdn.com/victron/original/3X/8/d/8d4a955b54060ca142e5fb1eee5d245425a98317.png) ---
**Author:** ![Vladyslav\_Kh](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/vladyslav_kh/32/46516_2.png) [@Vladyslav\_Kh](https://community.victronenergy.com/u/Vladyslav_Kh)\ **Post date:** [27 March 2026 20:33 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/5 "2026-03-27T20:33:29Z")
You need to disable VE.Can and MPPT calculator will propose 150/35 (VE.direct connection) ![image](https://europe1.discourse-cdn.com/victron/original/3X/e/2/e2d1799b1d63a31a0ecf08a338752c9dce042613.png) ---
**Author:** ![robovanbasten](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@robovanbasten](https://community.victronenergy.com/u/robovanbasten)\ **Post date:** [27 March 2026 22:36 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/6 "2026-03-27T22:36:23Z")
Does this design look ok? 2S2P connected, using MC4 branches near the array to run only two cables (one positive, one negative). ![image](https://europe1.discourse-cdn.com/victron/original/3X/c/3/c3b62e7466c066db1c57ee332fa7569995049266.png) ---
**Author:** ![lxonline](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/lxonline/32/25567_2.png) [@lxonline](https://community.victronenergy.com/u/lxonline)\ **Post date:** [28 March 2026 05:21 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/7 "2026-03-28T05:21:03Z")
Check the Y branches can handle the isc of the parallel, many can only do up to 30A. And some cheaper ones even less. Oddly i get the mppt 150/35 when i use the calculator. Are you changing any other parameters? [fba1b621-486a-4788-9da7-f797c543b91b.pdf](https://community.victronenergy.com/uploads/short-url/tnLPH79fYxrPykggtHjkjV8jG4v.pdf) (772.1 KB) The 150/45 is a (better) great choice if you don’t want any clipping. ---
**Author:** ![1234enough](https://avatars.discourse-cdn.com/v4/letter/1/ea666f/32.png) [@1234enough](https://community.victronenergy.com/u/1234enough)\ **Post date:** [28 March 2026 06:49 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/8 "2026-03-28T06:49:49Z")
If you are uk , try out [https://www.cityplumbing.co.uk/c/product/renewables/solar-pv/solar-pv-panels/c/1870007/](https://www.cityplumbing.co.uk/c/product/renewables/solar-pv/solar-pv-panels/c/1870007/) Far cheaper than your links. ---
**Author:** ![robovanbasten](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@robovanbasten](https://community.victronenergy.com/u/robovanbasten)\ **Post date:** [1 April 2026 06:38 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/9 "2026-04-01T06:38:46Z")
Hi all, just following up my initial question. I have two options on panel selection, and I’d really appreciate some help deciding which one is better. **Option 1** : 3 x Aiko 650w (1950w total) in portrait, using a Victron 250/60 Or **Option 2** : 4 x Perlight 415w (1660w total), 2S2P configuration, using a Victron 150/30 or 150/45 The Aiko’s are silver frame, and I guess mostly designed for commercial uses, not to say they can’t be used in a residential use case like mine? Being in portrait I’m thinking 2 or 3 horizontal rails to mount them. The Perlight’s are All Black, and are designed for residential, but are a lower wattage. Also, would need 4 vertical rails to mount them. Any help/reasoning for selecting one or the other would be great as I’m stuck on the fence. Chris ---
**Author:** ![robovanbasten](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@robovanbasten](https://community.victronenergy.com/u/robovanbasten)\ **Post date:** [5 April 2026 13:46 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/10 "2026-04-05T13:46:03Z")
Went with option 2 ---
**Author:** ![robovanbasten](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@robovanbasten](https://community.victronenergy.com/u/robovanbasten)\ **Post date:** [5 April 2026 19:42 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/11 "2026-04-05T19:42:05Z")
@lxonline , can you tell me what size DC isolator I would need here? 🤔 ![design](https://europe1.discourse-cdn.com/victron/original/3X/0/2/028c1522ce767d96fdc97058663c8ed073c72bb3.png) ---
**Author:** ![lxonline](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/lxonline/32/25567_2.png) [@lxonline](https://community.victronenergy.com/u/lxonline)\ **Post date:** [5 April 2026 19:59 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/12 "2026-04-05T19:59:08Z")
11.12x2 x1.25 =28A - what ever is closest to that figure that you can get supplied. So probably a 32A DC breaker. Most ideally you also want to fuse each string. Easy to do if you can get the fused MC4 connector sets. ---
**Author:** ![robovanbasten](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@robovanbasten](https://community.victronenergy.com/u/robovanbasten)\ **Post date:** [6 April 2026 07:12 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/13 "2026-04-06T07:12:19Z")
Is this one suitable? [Isolator](https://www.sunshinesolar.co.uk/Item/DCSWMC4-1S?gad_source=1&gad_campaignid=22818938289&gbraid=0AAAAAD_S6WGsJvV_1cdGhNcjKt2thUAVS&gclid=EAIaIQobChMIv8ui6vHPkwMV3o9QBh3yGj1jEAQYASABEgLPo_D_BwE) ---
**Author:** ![lxonline](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/lxonline/32/25567_2.png) [@lxonline](https://community.victronenergy.com/u/lxonline)\ **Post date:** [6 April 2026 07:25 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/14 "2026-04-06T07:25:53Z")
Neat solution. I will say yes if there is current limiting on each string like a fuse. Check your regulations im sure there are some related to this. ---
**Author:** ![robovanbasten](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@robovanbasten](https://community.victronenergy.com/u/robovanbasten)\ **Post date:** [6 April 2026 08:02 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/15 "2026-04-06T08:02:45Z")
In-line fuse like [this](https://www.slocable.com.cn/solar-panel-mc4-inline-fuse-connector-1000v-product/) I guess these are only needed on the positive cable and I could install one of these at the DC isolator? ---
**Author:** ![lxonline](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/lxonline/32/25567_2.png) [@lxonline](https://community.victronenergy.com/u/lxonline)\ **Post date:** [6 April 2026 08:14 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/16 "2026-04-06T08:14:24Z")
Those inline ones are the most convenient Each string should be fused before they are combined. Easy enough to do since you will probably/possibly need to make a jumper from one end of the array to the Y connector. Just plan it so the correct one is fused. (Unless the solar panels have nice leads on them. ---
**Author:** ![robovanbasten](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@robovanbasten](https://community.victronenergy.com/u/robovanbasten)\ **Post date:** [7 April 2026 07:46 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/17 "2026-04-07T07:46:12Z")
If I used one of [these](https://ebay.us/m/KDEHgD), would I still need inline fuses at the Y positive connector? ---
**Author:** ![lxonline](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/lxonline/32/25567_2.png) [@lxonline](https://community.victronenergy.com/u/lxonline)\ **Post date:** [7 April 2026 09:10 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/18 "2026-04-07T09:10:44Z")
Ideally each string is individually fused. Then after the combiner (y connector in this case) the breaker/ disconnect like the one you linked will be good. ---
**Author:** ![robovanbasten](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@robovanbasten](https://community.victronenergy.com/u/robovanbasten)\ **Post date:** [28 April 2026 17:22 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/19 "2026-04-28T17:22:13Z")
Hi @lxonline , can you tell me what size mega fuse I should be using in my lynx distributor? If you recall from above conversation, I’m using a mppt 150/45 (that has 4 x 415w perlight panels in 2s2p configuration). I’ll be using a short set (0.8m) of battery cables (16mm2 [6 AWG]) from the mppt to the lynx. Just pulling the last bits together. TIA, Chris ---
**Author:** ![lxonline](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/lxonline/32/25567_2.png) [@lxonline](https://community.victronenergy.com/u/lxonline)\ **Post date:** [28 April 2026 17:45 UTC](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608/20 "2026-04-28T17:45:57Z")
Hi @robovanbasten > **[4.2. Battery - 4. Installation](https://www.victronenergy.com/media/pg/Manual_SmartSolar_MPPT_150-35__150-45/en/installation.html#UUID-3208a08d-9911-3e75-db99-b5a1fd348b6b)** > > The DC (PV) input is not isolated from the battery circuit. Therefore the PV, battery and control circuit are considered hazardous and should not be user accessible. 50-60A shown in the manual. [Next page](https://community.victronenergy.com/t/solar-upgrade-project-which-panels-and-mppt/55608.md?page=2)